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authorLinus Torvalds <torvalds@linux-foundation.org>2021-04-28 22:37:53 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2021-04-28 22:37:53 +0300
commit0ff0edb550e256597e505eff308f90d9a0b6677c (patch)
tree6d96f53e70f2bdec49627e30c2645ee97b987848
parent9a45da9270b64b14e154093c28f746d861ab8c61 (diff)
parentf4abe9967c6fdb511ee567e129a014b60945ab93 (diff)
downloadlinux-0ff0edb550e256597e505eff308f90d9a0b6677c.tar.xz
Merge tag 'locking-core-2021-04-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull locking updates from Ingo Molnar: - rtmutex cleanup & spring cleaning pass that removes ~400 lines of code - Futex simplifications & cleanups - Add debugging to the CSD code, to help track down a tenacious race (or hw problem) - Add lockdep_assert_not_held(), to allow code to require a lock to not be held, and propagate this into the ath10k driver - Misc LKMM documentation updates - Misc KCSAN updates: cleanups & documentation updates - Misc fixes and cleanups - Fix locktorture bugs with ww_mutexes * tag 'locking-core-2021-04-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (44 commits) kcsan: Fix printk format string static_call: Relax static_call_update() function argument type static_call: Fix unused variable warn w/o MODULE locking/rtmutex: Clean up signal handling in __rt_mutex_slowlock() locking/rtmutex: Restrict the trylock WARN_ON() to debug locking/rtmutex: Fix misleading comment in rt_mutex_postunlock() locking/rtmutex: Consolidate the fast/slowpath invocation locking/rtmutex: Make text section and inlining consistent locking/rtmutex: Move debug functions as inlines into common header locking/rtmutex: Decrapify __rt_mutex_init() locking/rtmutex: Remove pointless CONFIG_RT_MUTEXES=n stubs locking/rtmutex: Inline chainwalk depth check locking/rtmutex: Move rt_mutex_debug_task_free() to rtmutex.c locking/rtmutex: Remove empty and unused debug stubs locking/rtmutex: Consolidate rt_mutex_init() locking/rtmutex: Remove output from deadlock detector locking/rtmutex: Remove rtmutex deadlock tester leftovers locking/rtmutex: Remove rt_mutex_timed_lock() MAINTAINERS: Add myself as futex reviewer locking/mutex: Remove repeated declaration ...
-rw-r--r--Documentation/admin-guide/kernel-parameters.txt10
-rw-r--r--Documentation/dev-tools/kcsan.rst3
-rw-r--r--MAINTAINERS1
-rw-r--r--arch/arm/include/asm/spinlock.h2
-rw-r--r--arch/x86/include/asm/jump_label.h4
-rw-r--r--drivers/net/wireless/ath/ath10k/mac.c2
-rw-r--r--include/linux/kcsan-checks.h6
-rw-r--r--include/linux/kcsan.h7
-rw-r--r--include/linux/lockdep.h20
-rw-r--r--include/linux/mutex.h4
-rw-r--r--include/linux/rtmutex.h35
-rw-r--r--include/linux/rwsem.h2
-rw-r--r--include/linux/static_call.h4
-rw-r--r--include/linux/ww_mutex.h17
-rw-r--r--kernel/futex.c29
-rw-r--r--kernel/kcsan/Makefile4
-rw-r--r--kernel/kcsan/atomic.h5
-rw-r--r--kernel/kcsan/core.c7
-rw-r--r--kernel/kcsan/debugfs.c9
-rw-r--r--kernel/kcsan/encoding.h5
-rw-r--r--kernel/kcsan/kcsan.h8
-rw-r--r--kernel/kcsan/kcsan_test.c (renamed from kernel/kcsan/kcsan-test.c)118
-rw-r--r--kernel/kcsan/report.c5
-rw-r--r--kernel/kcsan/selftest.c5
-rw-r--r--kernel/locking/Makefile2
-rw-r--r--kernel/locking/lockdep.c19
-rw-r--r--kernel/locking/lockdep_proc.c2
-rw-r--r--kernel/locking/locktorture.c146
-rw-r--r--kernel/locking/mcs_spinlock.h2
-rw-r--r--kernel/locking/mutex.c4
-rw-r--r--kernel/locking/osq_lock.c4
-rw-r--r--kernel/locking/rtmutex-debug.c182
-rw-r--r--kernel/locking/rtmutex-debug.h37
-rw-r--r--kernel/locking/rtmutex.c432
-rw-r--r--kernel/locking/rtmutex.h35
-rw-r--r--kernel/locking/rtmutex_common.h105
-rw-r--r--kernel/locking/rwsem.c4
-rw-r--r--kernel/locking/spinlock.c4
-rw-r--r--kernel/sched/core.c18
-rw-r--r--kernel/smp.c276
-rw-r--r--kernel/static_call.c4
-rw-r--r--lib/Kconfig.kcsan5
-rw-r--r--tools/memory-model/Documentation/access-marking.txt479
-rw-r--r--tools/memory-model/Documentation/simple.txt1
44 files changed, 1246 insertions, 827 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index fa08ec0dfbe7..54582ca6c4f9 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -782,6 +782,16 @@
cs89x0_media= [HW,NET]
Format: { rj45 | aui | bnc }
+ csdlock_debug= [KNL] Enable debug add-ons of cross-CPU function call
+ handling. When switched on, additional debug data is
+ printed to the console in case a hanging CPU is
+ detected, and that CPU is pinged again in order to try
+ to resolve the hang situation.
+ 0: disable csdlock debugging (default)
+ 1: enable basic csdlock debugging (minor impact)
+ ext: enable extended csdlock debugging (more impact,
+ but more data)
+
dasd= [HW,NET]
See header of drivers/s390/block/dasd_devmap.c.
diff --git a/Documentation/dev-tools/kcsan.rst b/Documentation/dev-tools/kcsan.rst
index be7a0b0e1f28..d85ce238ace7 100644
--- a/Documentation/dev-tools/kcsan.rst
+++ b/Documentation/dev-tools/kcsan.rst
@@ -1,3 +1,6 @@
+.. SPDX-License-Identifier: GPL-2.0
+.. Copyright (C) 2019, Google LLC.
+
The Kernel Concurrency Sanitizer (KCSAN)
========================================
diff --git a/MAINTAINERS b/MAINTAINERS
index e32c844a154a..85a39e13c6c6 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -7452,6 +7452,7 @@ M: Thomas Gleixner <tglx@linutronix.de>
M: Ingo Molnar <mingo@redhat.com>
R: Peter Zijlstra <peterz@infradead.org>
R: Darren Hart <dvhart@infradead.org>
+R: Davidlohr Bueso <dave@stgolabs.net>
L: linux-kernel@vger.kernel.org
S: Maintained
T: git git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git locking/core
diff --git a/arch/arm/include/asm/spinlock.h b/arch/arm/include/asm/spinlock.h
index 8f009e788ad4..f610a773f2be 100644
--- a/arch/arm/include/asm/spinlock.h
+++ b/arch/arm/include/asm/spinlock.h
@@ -22,7 +22,7 @@
* assembler to insert a extra (16-bit) IT instruction, depending on the
* presence or absence of neighbouring conditional instructions.
*
- * To avoid this unpredictableness, an approprite IT is inserted explicitly:
+ * To avoid this unpredictability, an appropriate IT is inserted explicitly:
* the assembler won't change IT instructions which are explicitly present
* in the input.
*/
diff --git a/arch/x86/include/asm/jump_label.h b/arch/x86/include/asm/jump_label.h
index 5ce342b91ff3..610a05374c02 100644
--- a/arch/x86/include/asm/jump_label.h
+++ b/arch/x86/include/asm/jump_label.h
@@ -14,7 +14,7 @@
#include <linux/stringify.h>
#include <linux/types.h>
-static __always_inline bool arch_static_branch(struct static_key *key, bool branch)
+static __always_inline bool arch_static_branch(struct static_key * const key, const bool branch)
{
asm_volatile_goto("1:"
".byte " __stringify(BYTES_NOP5) "\n\t"
@@ -30,7 +30,7 @@ l_yes:
return true;
}
-static __always_inline bool arch_static_branch_jump(struct static_key *key, bool branch)
+static __always_inline bool arch_static_branch_jump(struct static_key * const key, const bool branch)
{
asm_volatile_goto("1:"
".byte 0xe9\n\t .long %l[l_yes] - 2f\n\t"
diff --git a/drivers/net/wireless/ath/ath10k/mac.c b/drivers/net/wireless/ath/ath10k/mac.c
index bb6c5ee43ac0..5ce4f8d038b9 100644
--- a/drivers/net/wireless/ath/ath10k/mac.c
+++ b/drivers/net/wireless/ath/ath10k/mac.c
@@ -4727,6 +4727,8 @@ out:
/* Must not be called with conf_mutex held as workers can use that also. */
void ath10k_drain_tx(struct ath10k *ar)
{
+ lockdep_assert_not_held(&ar->conf_mutex);
+
/* make sure rcu-protected mac80211 tx path itself is drained */
synchronize_net();
diff --git a/include/linux/kcsan-checks.h b/include/linux/kcsan-checks.h
index cf14840609ce..9fd0ad80fef6 100644
--- a/include/linux/kcsan-checks.h
+++ b/include/linux/kcsan-checks.h
@@ -1,4 +1,10 @@
/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * KCSAN access checks and modifiers. These can be used to explicitly check
+ * uninstrumented accesses, or change KCSAN checking behaviour of accesses.
+ *
+ * Copyright (C) 2019, Google LLC.
+ */
#ifndef _LINUX_KCSAN_CHECKS_H
#define _LINUX_KCSAN_CHECKS_H
diff --git a/include/linux/kcsan.h b/include/linux/kcsan.h
index 53340d8789f9..fc266ecb2a4d 100644
--- a/include/linux/kcsan.h
+++ b/include/linux/kcsan.h
@@ -1,4 +1,11 @@
/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * The Kernel Concurrency Sanitizer (KCSAN) infrastructure. Public interface and
+ * data structures to set up runtime. See kcsan-checks.h for explicit checks and
+ * modifiers. For more info please see Documentation/dev-tools/kcsan.rst.
+ *
+ * Copyright (C) 2019, Google LLC.
+ */
#ifndef _LINUX_KCSAN_H
#define _LINUX_KCSAN_H
diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h
index 1c746139d5e3..5cf387813754 100644
--- a/include/linux/lockdep.h
+++ b/include/linux/lockdep.h
@@ -155,7 +155,7 @@ extern void lockdep_set_selftest_task(struct task_struct *task);
extern void lockdep_init_task(struct task_struct *task);
/*
- * Split the recrursion counter in two to readily detect 'off' vs recursion.
+ * Split the recursion counter in two to readily detect 'off' vs recursion.
*/
#define LOCKDEP_RECURSION_BITS 16
#define LOCKDEP_OFF (1U << LOCKDEP_RECURSION_BITS)
@@ -268,6 +268,11 @@ extern void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
extern void lock_release(struct lockdep_map *lock, unsigned long ip);
+/* lock_is_held_type() returns */
+#define LOCK_STATE_UNKNOWN -1
+#define LOCK_STATE_NOT_HELD 0
+#define LOCK_STATE_HELD 1
+
/*
* Same "read" as for lock_acquire(), except -1 means any.
*/
@@ -301,8 +306,14 @@ extern void lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie);
#define lockdep_depth(tsk) (debug_locks ? (tsk)->lockdep_depth : 0)
-#define lockdep_assert_held(l) do { \
- WARN_ON(debug_locks && !lockdep_is_held(l)); \
+#define lockdep_assert_held(l) do { \
+ WARN_ON(debug_locks && \
+ lockdep_is_held(l) == LOCK_STATE_NOT_HELD); \
+ } while (0)
+
+#define lockdep_assert_not_held(l) do { \
+ WARN_ON(debug_locks && \
+ lockdep_is_held(l) == LOCK_STATE_HELD); \
} while (0)
#define lockdep_assert_held_write(l) do { \
@@ -397,7 +408,8 @@ extern int lockdep_is_held(const void *);
#define lockdep_is_held_type(l, r) (1)
#define lockdep_assert_held(l) do { (void)(l); } while (0)
-#define lockdep_assert_held_write(l) do { (void)(l); } while (0)
+#define lockdep_assert_not_held(l) do { (void)(l); } while (0)
+#define lockdep_assert_held_write(l) do { (void)(l); } while (0)
#define lockdep_assert_held_read(l) do { (void)(l); } while (0)
#define lockdep_assert_held_once(l) do { (void)(l); } while (0)
#define lockdep_assert_none_held_once() do { } while (0)
diff --git a/include/linux/mutex.h b/include/linux/mutex.h
index 515cff77a4f4..e19323521f9c 100644
--- a/include/linux/mutex.h
+++ b/include/linux/mutex.h
@@ -20,6 +20,7 @@
#include <linux/osq_lock.h>
#include <linux/debug_locks.h>
+struct ww_class;
struct ww_acquire_ctx;
/*
@@ -65,9 +66,6 @@ struct mutex {
#endif
};
-struct ww_class;
-struct ww_acquire_ctx;
-
struct ww_mutex {
struct mutex base;
struct ww_acquire_ctx *ctx;
diff --git a/include/linux/rtmutex.h b/include/linux/rtmutex.h
index 6fd615a0eea9..d1672de9ca89 100644
--- a/include/linux/rtmutex.h
+++ b/include/linux/rtmutex.h
@@ -31,12 +31,6 @@ struct rt_mutex {
raw_spinlock_t wait_lock;
struct rb_root_cached waiters;
struct task_struct *owner;
-#ifdef CONFIG_DEBUG_RT_MUTEXES
- int save_state;
- const char *name, *file;
- int line;
- void *magic;
-#endif
#ifdef CONFIG_DEBUG_LOCK_ALLOC
struct lockdep_map dep_map;
#endif
@@ -46,35 +40,17 @@ struct rt_mutex_waiter;
struct hrtimer_sleeper;
#ifdef CONFIG_DEBUG_RT_MUTEXES
- extern int rt_mutex_debug_check_no_locks_freed(const void *from,
- unsigned long len);
- extern void rt_mutex_debug_check_no_locks_held(struct task_struct *task);
+extern void rt_mutex_debug_task_free(struct task_struct *tsk);
#else
- static inline int rt_mutex_debug_check_no_locks_freed(const void *from,
- unsigned long len)
- {
- return 0;
- }
-# define rt_mutex_debug_check_no_locks_held(task) do { } while (0)
+static inline void rt_mutex_debug_task_free(struct task_struct *tsk) { }
#endif
-#ifdef CONFIG_DEBUG_RT_MUTEXES
-# define __DEBUG_RT_MUTEX_INITIALIZER(mutexname) \
- , .name = #mutexname, .file = __FILE__, .line = __LINE__
-
-# define rt_mutex_init(mutex) \
+#define rt_mutex_init(mutex) \
do { \
static struct lock_class_key __key; \
__rt_mutex_init(mutex, __func__, &__key); \
} while (0)
- extern void rt_mutex_debug_task_free(struct task_struct *tsk);
-#else
-# define __DEBUG_RT_MUTEX_INITIALIZER(mutexname)
-# define rt_mutex_init(mutex) __rt_mutex_init(mutex, NULL, NULL)
-# define rt_mutex_debug_task_free(t) do { } while (0)
-#endif
-
#ifdef CONFIG_DEBUG_LOCK_ALLOC
#define __DEP_MAP_RT_MUTEX_INITIALIZER(mutexname) \
, .dep_map = { .name = #mutexname }
@@ -86,7 +62,6 @@ do { \
{ .wait_lock = __RAW_SPIN_LOCK_UNLOCKED(mutexname.wait_lock) \
, .waiters = RB_ROOT_CACHED \
, .owner = NULL \
- __DEBUG_RT_MUTEX_INITIALIZER(mutexname) \
__DEP_MAP_RT_MUTEX_INITIALIZER(mutexname)}
#define DEFINE_RT_MUTEX(mutexname) \
@@ -104,7 +79,6 @@ static inline int rt_mutex_is_locked(struct rt_mutex *lock)
}
extern void __rt_mutex_init(struct rt_mutex *lock, const char *name, struct lock_class_key *key);
-extern void rt_mutex_destroy(struct rt_mutex *lock);
#ifdef CONFIG_DEBUG_LOCK_ALLOC
extern void rt_mutex_lock_nested(struct rt_mutex *lock, unsigned int subclass);
@@ -115,9 +89,6 @@ extern void rt_mutex_lock(struct rt_mutex *lock);
#endif
extern int rt_mutex_lock_interruptible(struct rt_mutex *lock);
-extern int rt_mutex_timed_lock(struct rt_mutex *lock,
- struct hrtimer_sleeper *timeout);
-
extern int rt_mutex_trylock(struct rt_mutex *lock);
extern void rt_mutex_unlock(struct rt_mutex *lock);
diff --git a/include/linux/rwsem.h b/include/linux/rwsem.h
index 4c715be48717..a66038d88878 100644
--- a/include/linux/rwsem.h
+++ b/include/linux/rwsem.h
@@ -110,7 +110,7 @@ do { \
/*
* This is the same regardless of which rwsem implementation that is being used.
- * It is just a heuristic meant to be called by somebody alreadying holding the
+ * It is just a heuristic meant to be called by somebody already holding the
* rwsem to see if somebody from an incompatible type is wanting access to the
* lock.
*/
diff --git a/include/linux/static_call.h b/include/linux/static_call.h
index e01b61ab86b1..fc94faa53b5b 100644
--- a/include/linux/static_call.h
+++ b/include/linux/static_call.h
@@ -118,9 +118,9 @@ extern void arch_static_call_transform(void *site, void *tramp, void *func, bool
#define static_call_update(name, func) \
({ \
- BUILD_BUG_ON(!__same_type(*(func), STATIC_CALL_TRAMP(name))); \
+ typeof(&STATIC_CALL_TRAMP(name)) __F = (func); \
__static_call_update(&STATIC_CALL_KEY(name), \
- STATIC_CALL_TRAMP_ADDR(name), func); \
+ STATIC_CALL_TRAMP_ADDR(name), __F); \
})
#define static_call_query(name) (READ_ONCE(STATIC_CALL_KEY(name).func))
diff --git a/include/linux/ww_mutex.h b/include/linux/ww_mutex.h
index 6ecf2a0220db..b77f39f319ad 100644
--- a/include/linux/ww_mutex.h
+++ b/include/linux/ww_mutex.h
@@ -48,39 +48,26 @@ struct ww_acquire_ctx {
#endif
};
-#ifdef CONFIG_DEBUG_LOCK_ALLOC
-# define __WW_CLASS_MUTEX_INITIALIZER(lockname, class) \
- , .ww_class = class
-#else
-# define __WW_CLASS_MUTEX_INITIALIZER(lockname, class)
-#endif
-
#define __WW_CLASS_INITIALIZER(ww_class, _is_wait_die) \
{ .stamp = ATOMIC_LONG_INIT(0) \
, .acquire_name = #ww_class "_acquire" \
, .mutex_name = #ww_class "_mutex" \
, .is_wait_die = _is_wait_die }
-#define __WW_MUTEX_INITIALIZER(lockname, class) \
- { .base = __MUTEX_INITIALIZER(lockname.base) \
- __WW_CLASS_MUTEX_INITIALIZER(lockname, class) }
-
#define DEFINE_WD_CLASS(classname) \
struct ww_class classname = __WW_CLASS_INITIALIZER(classname, 1)
#define DEFINE_WW_CLASS(classname) \
struct ww_class classname = __WW_CLASS_INITIALIZER(classname, 0)
-#define DEFINE_WW_MUTEX(mutexname, ww_class) \
- struct ww_mutex mutexname = __WW_MUTEX_INITIALIZER(mutexname, ww_class)
-
/**
* ww_mutex_init - initialize the w/w mutex
* @lock: the mutex to be initialized
* @ww_class: the w/w class the mutex should belong to
*
* Initialize the w/w mutex to unlocked state and associate it with the given
- * class.
+ * class. Static define macro for w/w mutex is not provided and this function
+ * is the only way to properly initialize the w/w mutex.
*
* It is not allowed to initialize an already locked mutex.
*/
diff --git a/kernel/futex.c b/kernel/futex.c
index 00febd6dea9c..c98b825da9cf 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -981,6 +981,7 @@ static inline void exit_pi_state_list(struct task_struct *curr) { }
* p->pi_lock:
*
* p->pi_state_list -> pi_state->list, relation
+ * pi_mutex->owner -> pi_state->owner, relation
*
* pi_state->refcount:
*
@@ -1494,13 +1495,14 @@ static void mark_wake_futex(struct wake_q_head *wake_q, struct futex_q *q)
static int wake_futex_pi(u32 __user *uaddr, u32 uval, struct futex_pi_state *pi_state)
{
u32 curval, newval;
+ struct rt_mutex_waiter *top_waiter;
struct task_struct *new_owner;
bool postunlock = false;
DEFINE_WAKE_Q(wake_q);
int ret = 0;
- new_owner = rt_mutex_next_owner(&pi_state->pi_mutex);
- if (WARN_ON_ONCE(!new_owner)) {
+ top_waiter = rt_mutex_top_waiter(&pi_state->pi_mutex);
+ if (WARN_ON_ONCE(!top_waiter)) {
/*
* As per the comment in futex_unlock_pi() this should not happen.
*
@@ -1513,6 +1515,8 @@ static int wake_futex_pi(u32 __user *uaddr, u32 uval, struct futex_pi_state *pi_
goto out_unlock;
}
+ new_owner = top_waiter->task;
+
/*
* We pass it to the next owner. The WAITERS bit is always kept
* enabled while there is PI state around. We cleanup the owner
@@ -2315,19 +2319,15 @@ retry:
/*
* PI futexes can not be requeued and must remove themself from the
- * hash bucket. The hash bucket lock (i.e. lock_ptr) is held on entry
- * and dropped here.
+ * hash bucket. The hash bucket lock (i.e. lock_ptr) is held.
*/
static void unqueue_me_pi(struct futex_q *q)
- __releases(q->lock_ptr)
{
__unqueue_futex(q);
BUG_ON(!q->pi_state);
put_pi_state(q->pi_state);
q->pi_state = NULL;
-
- spin_unlock(q->lock_ptr);
}
static int __fixup_pi_state_owner(u32 __user *uaddr, struct futex_q *q,
@@ -2909,8 +2909,8 @@ no_block:
if (res)
ret = (res < 0) ? res : 0;
- /* Unqueue and drop the lock */
unqueue_me_pi(&q);
+ spin_unlock(q.lock_ptr);
goto out;
out_unlock_put_key:
@@ -3237,15 +3237,14 @@ static int futex_wait_requeue_pi(u32 __user *uaddr, unsigned int flags,
* reference count.
*/
- /* Check if the requeue code acquired the second futex for us. */
+ /*
+ * Check if the requeue code acquired the second futex for us and do
+ * any pertinent fixup.
+ */
if (!q.rt_waiter) {
- /*
- * Got the lock. We might not be the anticipated owner if we
- * did a lock-steal - fix up the PI-state in that case.
- */
if (q.pi_state && (q.pi_state->owner != current)) {
spin_lock(q.lock_ptr);
- ret = fixup_pi_state_owner(uaddr2, &q, current);
+ ret = fixup_owner(uaddr2, &q, true);
/*
* Drop the reference to the pi state which
* the requeue_pi() code acquired for us.
@@ -3287,8 +3286,8 @@ static int futex_wait_requeue_pi(u32 __user *uaddr, unsigned int flags,
if (res)
ret = (res < 0) ? res : 0;
- /* Unqueue and drop the lock. */
unqueue_me_pi(&q);
+ spin_unlock(q.lock_ptr);
}
if (ret == -EINTR) {
diff --git a/kernel/kcsan/Makefile b/kernel/kcsan/Makefile
index 65ca5539c470..c2bb07f5bcc7 100644
--- a/kernel/kcsan/Makefile
+++ b/kernel/kcsan/Makefile
@@ -13,5 +13,5 @@ CFLAGS_core.o := $(call cc-option,-fno-conserve-stack) \
obj-y := core.o debugfs.o report.o
obj-$(CONFIG_KCSAN_SELFTEST) += selftest.o
-CFLAGS_kcsan-test.o := $(CFLAGS_KCSAN) -g -fno-omit-frame-pointer
-obj-$(CONFIG_KCSAN_TEST) += kcsan-test.o
+CFLAGS_kcsan_test.o := $(CFLAGS_KCSAN) -g -fno-omit-frame-pointer
+obj-$(CONFIG_KCSAN_KUNIT_TEST) += kcsan_test.o
diff --git a/kernel/kcsan/atomic.h b/kernel/kcsan/atomic.h
index 75fe701f4127..530ae1bda8e7 100644
--- a/kernel/kcsan/atomic.h
+++ b/kernel/kcsan/atomic.h
@@ -1,4 +1,9 @@
/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Rules for implicitly atomic memory accesses.
+ *
+ * Copyright (C) 2019, Google LLC.
+ */
#ifndef _KERNEL_KCSAN_ATOMIC_H
#define _KERNEL_KCSAN_ATOMIC_H
diff --git a/kernel/kcsan/core.c b/kernel/kcsan/core.c
index 3bf98db9c702..45c821d4e8bd 100644
--- a/kernel/kcsan/core.c
+++ b/kernel/kcsan/core.c
@@ -1,4 +1,9 @@
// SPDX-License-Identifier: GPL-2.0
+/*
+ * KCSAN core runtime.
+ *
+ * Copyright (C) 2019, Google LLC.
+ */
#define pr_fmt(fmt) "kcsan: " fmt
@@ -639,8 +644,6 @@ void __init kcsan_init(void)
BUG_ON(!in_task());
- kcsan_debugfs_init();
-
for_each_possible_cpu(cpu)
per_cpu(kcsan_rand_state, cpu) = (u32)get_cycles();
diff --git a/kernel/kcsan/debugfs.c b/kernel/kcsan/debugfs.c
index 3c8093a371b1..c1dd02f3be8b 100644
--- a/kernel/kcsan/debugfs.c
+++ b/kernel/kcsan/debugfs.c
@@ -1,4 +1,9 @@
// SPDX-License-Identifier: GPL-2.0
+/*
+ * KCSAN debugfs interface.
+ *
+ * Copyright (C) 2019, Google LLC.
+ */
#define pr_fmt(fmt) "kcsan: " fmt
@@ -261,7 +266,9 @@ static const struct file_operations debugfs_ops =
.release = single_release
};
-void __init kcsan_debugfs_init(void)
+static void __init kcsan_debugfs_init(void)
{
debugfs_create_file("kcsan", 0644, NULL, NULL, &debugfs_ops);
}
+
+late_initcall(kcsan_debugfs_init);
diff --git a/kernel/kcsan/encoding.h b/kernel/kcsan/encoding.h
index 7ee405524904..170a2bb22f53 100644
--- a/kernel/kcsan/encoding.h
+++ b/kernel/kcsan/encoding.h
@@ -1,4 +1,9 @@
/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * KCSAN watchpoint encoding.
+ *
+ * Copyright (C) 2019, Google LLC.
+ */
#ifndef _KERNEL_KCSAN_ENCODING_H
#define _KERNEL_KCSAN_ENCODING_H
diff --git a/kernel/kcsan/kcsan.h b/kernel/kcsan/kcsan.h
index 8d4bf3431b3c..9881099d4179 100644
--- a/kernel/kcsan/kcsan.h
+++ b/kernel/kcsan/kcsan.h
@@ -1,8 +1,9 @@
/* SPDX-License-Identifier: GPL-2.0 */
-
/*
* The Kernel Concurrency Sanitizer (KCSAN) infrastructure. For more info please
* see Documentation/dev-tools/kcsan.rst.
+ *
+ * Copyright (C) 2019, Google LLC.
*/
#ifndef _KERNEL_KCSAN_KCSAN_H
@@ -31,11 +32,6 @@ void kcsan_save_irqtrace(struct task_struct *task);
void kcsan_restore_irqtrace(struct task_struct *task);
/*
- * Initialize debugfs file.
- */
-void kcsan_debugfs_init(void);
-
-/*
* Statistics counters displayed via debugfs; should only be modified in
* slow-paths.
*/
diff --git a/kernel/kcsan/kcsan-test.c b/kernel/kcsan/kcsan_test.c
index ebe7fd245104..8bcffbdef3d3 100644
--- a/kernel/kcsan/kcsan-test.c
+++ b/kernel/kcsan/kcsan_test.c
@@ -13,6 +13,8 @@
* Author: Marco Elver <elver@google.com>
*/
+#define pr_fmt(fmt) "kcsan_test: " fmt
+
#include <kunit/test.h>
#include <linux/jiffies.h>
#include <linux/kcsan-checks.h>
@@ -951,22 +953,53 @@ static void test_atomic_builtins(struct kunit *test)
}
/*
- * Each test case is run with different numbers of threads. Until KUnit supports
- * passing arguments for each test case, we encode #threads in the test case
- * name (read by get_num_threads()). [The '-' was chosen as a stylistic
- * preference to separate test name and #threads.]
+ * Generate thread counts for all test cases. Values generated are in interval
+ * [2, 5] followed by exponentially increasing thread counts from 8 to 32.
*
* The thread counts are chosen to cover potentially interesting boundaries and
- * corner cases (range 2-5), and then stress the system with larger counts.
+ * corner cases (2 to 5), and then stress the system with larger counts.
*/
-#define KCSAN_KUNIT_CASE(test_name) \
- { .run_case = test_name, .name = #test_name "-02" }, \
- { .run_case = test_name, .name = #test_name "-03" }, \
- { .run_case = test_name, .name = #test_name "-04" }, \
- { .run_case = test_name, .name = #test_name "-05" }, \
- { .run_case = test_name, .name = #test_name "-08" }, \
- { .run_case = test_name, .name = #test_name "-16" }
+static const void *nthreads_gen_params(const void *prev, char *desc)
+{
+ long nthreads = (long)prev;
+
+ if (nthreads < 0 || nthreads >= 32)
+ nthreads = 0; /* stop */
+ else if (!nthreads)
+ nthreads = 2; /* initial value */
+ else if (nthreads < 5)
+ nthreads++;
+ else if (nthreads == 5)
+ nthreads = 8;
+ else
+ nthreads *= 2;
+ if (!IS_ENABLED(CONFIG_PREEMPT) || !IS_ENABLED(CONFIG_KCSAN_INTERRUPT_WATCHER)) {
+ /*
+ * Without any preemption, keep 2 CPUs free for other tasks, one
+ * of which is the main test case function checking for
+ * completion or failure.
+ */
+ const long min_unused_cpus = IS_ENABLED(CONFIG_PREEMPT_NONE) ? 2 : 0;
+ const long min_required_cpus = 2 + min_unused_cpus;
+
+ if (num_online_cpus() < min_required_cpus) {
+ pr_err_once("Too few online CPUs (%u < %ld) for test\n",
+ num_online_cpus(), min_required_cpus);
+ nthreads = 0;
+ } else if (nthreads >= num_online_cpus() - min_unused_cpus) {
+ /* Use negative value to indicate last param. */
+ nthreads = -(num_online_cpus() - min_unused_cpus);
+ pr_warn_once("Limiting number of threads to %ld (only %d online CPUs)\n",
+ -nthreads, num_online_cpus());
+ }
+ }
+
+ snprintf(desc, KUNIT_PARAM_DESC_SIZE, "threads=%ld", abs(nthreads));
+ return (void *)nthreads;
+}
+
+#define KCSAN_KUNIT_CASE(test_name) KUNIT_CASE_PARAM(test_name, nthreads_gen_params)
static struct kunit_case kcsan_test_cases[] = {
KCSAN_KUNIT_CASE(test_basic),
KCSAN_KUNIT_CASE(test_concurrent_races),
@@ -996,24 +1029,6 @@ static struct kunit_case kcsan_test_cases[] = {
/* ===== End test cases ===== */
-/* Get number of threads encoded in test name. */
-static bool __no_kcsan
-get_num_threads(const char *test, int *nthreads)
-{
- int len = strlen(test);
-
- if (WARN_ON(len < 3))
- return false;
-
- *nthreads = test[len - 1] - '0';
- *nthreads += (test[len - 2] - '0') * 10;
-
- if (WARN_ON(*nthreads < 0))
- return false;
-
- return true;
-}
-
/* Concurrent accesses from interrupts. */
__no_kcsan
static void access_thread_timer(struct timer_list *timer)
@@ -1076,9 +1091,6 @@ static int test_init(struct kunit *test)
if (!torture_init_begin((char *)test->name, 1))
return -EBUSY;
- if (!get_num_threads(test->name, &nthreads))
- goto err;
-
if (WARN_ON(threads))
goto err;
@@ -1087,38 +1099,18 @@ static int test_init(struct kunit *test)
goto err;
}
- if (!IS_ENABLED(CONFIG_PREEMPT) || !IS_ENABLED(CONFIG_KCSAN_INTERRUPT_WATCHER)) {
- /*
- * Without any preemption, keep 2 CPUs free for other tasks, one
- * of which is the main test case function checking for
- * completion or failure.
- */
- const int min_unused_cpus = IS_ENABLED(CONFIG_PREEMPT_NONE) ? 2 : 0;
- const int min_required_cpus = 2 + min_unused_cpus;
+ nthreads = abs((long)test->param_value);
+ if (WARN_ON(!nthreads))
+ goto err;
- if (num_online_cpus() < min_required_cpus) {
- pr_err("%s: too few online CPUs (%u < %d) for test",
- test->name, num_online_cpus(), min_required_cpus);
- goto err;
- } else if (nthreads > num_online_cpus() - min_unused_cpus) {
- nthreads = num_online_cpus() - min_unused_cpus;
- pr_warn("%s: limiting number of threads to %d\n",
- test->name, nthreads);
- }
- }
+ threads = kcalloc(nthreads + 1, sizeof(struct task_struct *), GFP_KERNEL);
+ if (WARN_ON(!threads))
+ goto err;
- if (nthreads) {
- threads = kcalloc(nthreads + 1, sizeof(struct task_struct *),
- GFP_KERNEL);
- if (WARN_ON(!threads))
+ threads[nthreads] = NULL;
+ for (i = 0; i < nthreads; ++i) {
+ if (torture_create_kthread(access_thread, NULL, threads[i]))
goto err;
-
- threads[nthreads] = NULL;
- for (i = 0; i < nthreads; ++i) {
- if (torture_create_kthread(access_thread, NULL,
- threads[i]))
- goto err;
- }
}
torture_init_end();
@@ -1156,7 +1148,7 @@ static void test_exit(struct kunit *test)
}
static struct kunit_suite kcsan_test_suite = {
- .name = "kcsan-test",
+ .name = "kcsan",
.test_cases = kcsan_test_cases,
.init = test_init,
.exit = test_exit,
diff --git a/kernel/kcsan/report.c b/kernel/kcsan/report.c
index d3bf87e6007c..13dce3c664d6 100644
--- a/kernel/kcsan/report.c
+++ b/kernel/kcsan/report.c
@@ -1,4 +1,9 @@
// SPDX-License-Identifier: GPL-2.0
+/*
+ * KCSAN reporting.
+ *
+ * Copyright (C) 2019, Google LLC.
+ */
#include <linux/debug_locks.h>
#include <linux/delay.h>
diff --git a/kernel/kcsan/selftest.c b/kernel/kcsan/selftest.c
index 9014a3a82cf9..7f29cb0f5e63 100644
--- a/kernel/kcsan/selftest.c
+++ b/kernel/kcsan/selftest.c
@@ -1,4 +1,9 @@
// SPDX-License-Identifier: GPL-2.0
+/*
+ * KCSAN short boot-time selftests.
+ *
+ * Copyright (C) 2019, Google LLC.
+ */
#define pr_fmt(fmt) "kcsan: " fmt
diff --git a/kernel/locking/Makefile b/kernel/locking/Makefile
index 8838f1d7c4a2..3572808223e4 100644
--- a/kernel/locking/Makefile
+++ b/kernel/locking/Makefile
@@ -12,7 +12,6 @@ ifdef CONFIG_FUNCTION_TRACER
CFLAGS_REMOVE_lockdep.o = $(CC_FLAGS_FTRACE)
CFLAGS_REMOVE_lockdep_proc.o = $(CC_FLAGS_FTRACE)
CFLAGS_REMOVE_mutex-debug.o = $(CC_FLAGS_FTRACE)
-CFLAGS_REMOVE_rtmutex-debug.o = $(CC_FLAGS_FTRACE)
endif
obj-$(CONFIG_DEBUG_IRQFLAGS) += irqflag-debug.o
@@ -26,7 +25,6 @@ obj-$(CONFIG_LOCK_SPIN_ON_OWNER) += osq_lock.o
obj-$(CONFIG_PROVE_LOCKING) += spinlock.o
obj-$(CONFIG_QUEUED_SPINLOCKS) += qspinlock.o
obj-$(CONFIG_RT_MUTEXES) += rtmutex.o
-obj-$(CONFIG_DEBUG_RT_MUTEXES) += rtmutex-debug.o
obj-$(CONFIG_DEBUG_SPINLOCK) += spinlock.o
obj-$(CONFIG_DEBUG_SPINLOCK) += spinlock_debug.o
obj-$(CONFIG_QUEUED_RWLOCKS) += qrwlock.o
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index ef28a0b9cf1e..48d736aa03b2 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -54,6 +54,7 @@
#include <linux/nmi.h>
#include <linux/rcupdate.h>
#include <linux/kprobes.h>
+#include <linux/lockdep.h>
#include <asm/sections.h>
@@ -1747,7 +1748,7 @@ static enum bfs_result __bfs(struct lock_list *source_entry,
/*
* Step 4: if not match, expand the path by adding the
- * forward or backwards dependencis in the search
+ * forward or backwards dependencies in the search
*
*/
first = true;
@@ -1916,7 +1917,7 @@ print_circular_bug_header(struct lock_list *entry, unsigned int depth,
* -> B is -(ER)-> or -(EN)->, then we don't need to add A -> B into the
* dependency graph, as any strong path ..-> A -> B ->.. we can get with
* having dependency A -> B, we could already get a equivalent path ..-> A ->
- * .. -> B -> .. with A -> .. -> B. Therefore A -> B is reduntant.
+ * .. -> B -> .. with A -> .. -> B. Therefore A -> B is redundant.
*
* We need to make sure both the start and the end of A -> .. -> B is not
* weaker than A -> B. For the start part, please see the comment in
@@ -5253,13 +5254,13 @@ int __lock_is_held(const struct lockdep_map *lock, int read)
if (match_held_lock(hlock, lock)) {
if (read == -1 || hlock->read == read)
- return 1;
+ return LOCK_STATE_HELD;
- return 0;
+ return LOCK_STATE_NOT_HELD;
}
}
- return 0;
+ return LOCK_STATE_NOT_HELD;
}
static struct pin_cookie __lock_pin_lock(struct lockdep_map *lock)
@@ -5538,10 +5539,14 @@ EXPORT_SYMBOL_GPL(lock_release);
noinstr int lock_is_held_type(const struct lockdep_map *lock, int read)
{
unsigned long flags;
- int ret = 0;
+ int ret = LOCK_STATE_NOT_HELD;
+ /*
+ * Avoid false negative lockdep_assert_held() and
+ * lockdep_assert_not_held().
+ */
if (unlikely(!lockdep_enabled()))
- return 1; /* avoid false negative lockdep_assert_held() */
+ return LOCK_STATE_UNKNOWN;
raw_local_irq_save(flags);
check_flags(flags);
diff --git a/kernel/locking/lockdep_proc.c b/kernel/locking/lockdep_proc.c
index 02ef87f50df2..806978314496 100644
--- a/kernel/locking/lockdep_proc.c
+++ b/kernel/locking/lockdep_proc.c
@@ -348,7 +348,7 @@ static int lockdep_stats_show(struct seq_file *m, void *v)
debug_locks);
/*
- * Zappped classes and lockdep data buffers reuse statistics.
+ * Zapped classes and lockdep data buffers reuse statistics.
*/
seq_puts(m, "\n");
seq_printf(m, " zapped classes: %11lu\n",
diff --git a/kernel/locking/locktorture.c b/kernel/locking/locktorture.c
index 0ab94e1f1276..b3adb40549bf 100644
--- a/kernel/locking/locktorture.c
+++ b/kernel/locking/locktorture.c
@@ -76,13 +76,13 @@ static void lock_torture_cleanup(void);
struct lock_torture_ops {
void (*init)(void);
void (*exit)(void);
- int (*writelock)(void);
+ int (*writelock)(int tid);
void (*write_delay)(struct torture_random_state *trsp);
void (*task_boost)(struct torture_random_state *trsp);
- void (*writeunlock)(void);
- int (*readlock)(void);
+ void (*writeunlock)(int tid);
+ int (*readlock)(int tid);
void (*read_delay)(struct torture_random_state *trsp);
- void (*readunlock)(void);
+ void (*readunlock)(int tid);
unsigned long flags; /* for irq spinlocks */
const char *name;
@@ -105,7 +105,7 @@ static struct lock_torture_cxt cxt = { 0, 0, false, false,
* Definitions for lock torture testing.
*/
-static int torture_lock_busted_write_lock(void)
+static int torture_lock_busted_write_lock(int tid __maybe_unused)
{
return 0; /* BUGGY, do not use in real life!!! */
}
@@ -122,7 +122,7 @@ static void torture_lock_busted_write_delay(struct torture_random_state *trsp)
torture_preempt_schedule(); /* Allow test to be preempted. */
}
-static void torture_lock_busted_write_unlock(void)
+static void torture_lock_busted_write_unlock(int tid __maybe_unused)
{
/* BUGGY, do not use in real life!!! */
}
@@ -145,7 +145,8 @@ static struct lock_torture_ops lock_busted_ops = {
static DEFINE_SPINLOCK(torture_spinlock);
-static int torture_spin_lock_write_lock(void) __acquires(torture_spinlock)
+static int torture_spin_lock_write_lock(int tid __maybe_unused)
+__acquires(torture_spinlock)
{
spin_lock(&torture_spinlock);
return 0;
@@ -169,7 +170,8 @@ static void torture_spin_lock_write_delay(struct torture_random_state *trsp)
torture_preempt_schedule(); /* Allow test to be preempted. */
}
-static void torture_spin_lock_write_unlock(void) __releases(torture_spinlock)
+static void torture_spin_lock_write_unlock(int tid __maybe_unused)
+__releases(torture_spinlock)
{
spin_unlock(&torture_spinlock);
}
@@ -185,7 +187,7 @@ static struct lock_torture_ops spin_lock_ops = {
.name = "spin_lock"
};
-static int torture_spin_lock_write_lock_irq(void)
+static int torture_spin_lock_write_lock_irq(int tid __maybe_unused)
__acquires(torture_spinlock)
{
unsigned long flags;
@@ -195,7 +197,7 @@ __acquires(torture_spinlock)
return 0;
}
-static void torture_lock_spin_write_unlock_irq(void)
+static void torture_lock_spin_write_unlock_irq(int tid __maybe_unused)
__releases(torture_spinlock)
{
spin_unlock_irqrestore(&torture_spinlock, cxt.cur_ops->flags);
@@ -214,7 +216,8 @@ static struct lock_torture_ops spin_lock_irq_ops = {
static DEFINE_RWLOCK(torture_rwlock);
-static int torture_rwlock_write_lock(void) __acquires(torture_rwlock)
+static int torture_rwlock_write_lock(int tid __maybe_unused)
+__acquires(torture_rwlock)
{
write_lock(&torture_rwlock);
return 0;
@@ -235,12 +238,14 @@ static void torture_rwlock_write_delay(struct torture_random_state *trsp)
udelay(shortdelay_us);
}
-static void torture_rwlock_write_unlock(void) __releases(torture_rwlock)
+static void torture_rwlock_write_unlock(int tid __maybe_unused)
+__releases(torture_rwlock)
{
write_unlock(&torture_rwlock);
}
-static int torture_rwlock_read_lock(void) __acquires(torture_rwlock)
+static int torture_rwlock_read_lock(int tid __maybe_unused)
+__acquires(torture_rwlock)
{
read_lock(&torture_rwlock);
return 0;
@@ -261,7 +266,8 @@ static void torture_rwlock_read_delay(struct torture_random_state *trsp)
udelay(shortdelay_us);
}
-static void torture_rwlock_read_unlock(void) __releases(torture_rwlock)
+static void torture_rwlock_read_unlock(int tid __maybe_unused)
+__releases(torture_rwlock)
{
read_unlock(&torture_rwlock);
}
@@ -277,7 +283,8 @@ static struct lock_torture_ops rw_lock_ops = {
.name = "rw_lock"
};
-static int torture_rwlock_write_lock_irq(void) __acquires(torture_rwlock)
+static int torture_rwlock_write_lock_irq(int tid __maybe_unused)
+__acquires(torture_rwlock)
{
unsigned long flags;
@@ -286,13 +293,14 @@ static int torture_rwlock_write_lock_irq(void) __acquires(torture_rwlock)
return 0;
}
-static void torture_rwlock_write_unlock_irq(void)
+static void torture_rwlock_write_unlock_irq(int tid __maybe_unused)
__releases(torture_rwlock)
{
write_unlock_irqrestore(&torture_rwlock, cxt.cur_ops->flags);
}
-static int torture_rwlock_read_lock_irq(void) __acquires(torture_rwlock)
+static int torture_rwlock_read_lock_irq(int tid __maybe_unused)
+__acquires(torture_rwlock)
{
unsigned long flags;
@@ -301,7 +309,7 @@ static int torture_rwlock_read_lock_irq(void) __acquires(torture_rwlock)
return 0;
}
-static void torture_rwlock_read_unlock_irq(void)
+static void torture_rwlock_read_unlock_irq(int tid __maybe_unused)
__releases(torture_rwlock)
{
read_unlock_irqrestore(&torture_rwlock, cxt.cur_ops->flags);
@@ -320,7 +328,8 @@ static struct lock_torture_ops rw_lock_irq_ops = {
static DEFINE_MUTEX(torture_mutex);
-static int torture_mutex_lock(void) __acquires(torture_mutex)
+static int torture_mutex_lock(int tid __maybe_unused)
+__acquires(torture_mutex)
{
mutex_lock(&torture_mutex);
return 0;
@@ -340,7 +349,8 @@ static void torture_mutex_delay(struct torture_random_state *trsp)
torture_preempt_schedule(); /* Allow test to be preempted. */
}
-static void torture_mutex_unlock(void) __releases(torture_mutex)
+static void torture_mutex_unlock(int tid __maybe_unused)
+__releases(torture_mutex)
{
mutex_unlock(&torture_mutex);
}
@@ -357,12 +367,34 @@ static struct lock_torture_ops mutex_lock_ops = {
};
#include <linux/ww_mutex.h>
+/*
+ * The torture ww_mutexes should belong to the same lock class as
+ * torture_ww_class to avoid lockdep problem. The ww_mutex_init()
+ * function is called for initialization to ensure that.
+ */
static DEFINE_WD_CLASS(torture_ww_class);
-static DEFINE_WW_MUTEX(torture_ww_mutex_0, &torture_ww_class);
-static DEFINE_WW_MUTEX(torture_ww_mutex_1, &torture_ww_class);
-static DEFINE_WW_MUTEX(torture_ww_mutex_2, &torture_ww_class);
+static struct ww_mutex torture_ww_mutex_0, torture_ww_mutex_1, torture_ww_mutex_2;
+static struct ww_acquire_ctx *ww_acquire_ctxs;
+
+static void torture_ww_mutex_init(void)
+{
+ ww_mutex_init(&torture_ww_mutex_0, &torture_ww_class);
+ ww_mutex_init(&torture_ww_mutex_1, &torture_ww_class);
+ ww_mutex_init(&torture_ww_mutex_2, &torture_ww_class);
+
+ ww_acquire_ctxs = kmalloc_array(cxt.nrealwriters_stress,
+ sizeof(*ww_acquire_ctxs),
+ GFP_KERNEL);
+ if (!ww_acquire_ctxs)
+ VERBOSE_TOROUT_STRING("ww_acquire_ctx: Out of memory");
+}
+
+static void torture_ww_mutex_exit(void)
+{
+ kfree(ww_acquire_ctxs);
+}
-static int torture_ww_mutex_lock(void)
+static int torture_ww_mutex_lock(int tid)
__acquires(torture_ww_mutex_0)
__acquires(torture_ww_mutex_1)
__acquires(torture_ww_mutex_2)
@@ -372,7 +404,7 @@ __acquires(torture_ww_mutex_2)
struct list_head link;
struct ww_mutex *lock;
} locks[3], *ll, *ln;
- struct ww_acquire_ctx ctx;
+ struct ww_acquire_ctx *ctx = &ww_acquire_ctxs[tid];
locks[0].lock = &torture_ww_mutex_0;
list_add(&locks[0].link, &list);
@@ -383,12 +415,12 @@ __acquires(torture_ww_mutex_2)
locks[2].lock = &torture_ww_mutex_2;
list_add(&locks[2].link, &list);
- ww_acquire_init(&ctx, &torture_ww_class);
+ ww_acquire_init(ctx, &torture_ww_class);
list_for_each_entry(ll, &list, link) {
int err;
- err = ww_mutex_lock(ll->lock, &ctx);
+ err = ww_mutex_lock(ll->lock, ctx);
if (!err)
continue;
@@ -399,25 +431,29 @@ __acquires(torture_ww_mutex_2)
if (err != -EDEADLK)
return err;
- ww_mutex_lock_slow(ll->lock, &ctx);
+ ww_mutex_lock_slow(ll->lock, ctx);
list_move(&ll->link, &list);
}
- ww_acquire_fini(&ctx);
return 0;
}
-static void torture_ww_mutex_unlock(void)
+static void torture_ww_mutex_unlock(int tid)
__releases(torture_ww_mutex_0)
__releases(torture_ww_mutex_1)
__releases(torture_ww_mutex_2)
{
+ struct ww_acquire_ctx *ctx = &ww_acquire_ctxs[tid];
+
ww_mutex_unlock(&torture_ww_mutex_0);
ww_mutex_unlock(&torture_ww_mutex_1);
ww_mutex_unlock(&torture_ww_mutex_2);
+ ww_acquire_fini(ctx);
}
static struct lock_torture_ops ww_mutex_lock_ops = {
+ .init = torture_ww_mutex_init,
+ .exit = torture_ww_mutex_exit,
.writelock = torture_ww_mutex_lock,
.write_delay = torture_mutex_delay,
.task_boost = torture_boost_dummy,
@@ -431,7 +467,8 @@ static struct lock_torture_ops ww_mutex_lock_ops = {
#ifdef CONFIG_RT_MUTEXES
static DEFINE_RT_MUTEX(torture_rtmutex);
-static int torture_rtmutex_lock(void) __acquires(torture_rtmutex)
+static int torture_rtmutex_lock(int tid __maybe_unused)
+__acquires(torture_rtmutex)
{
rt_mutex_lock(&torture_rtmutex);
return 0;
@@ -487,7 +524,8 @@ static void torture_rtmutex_delay(struct torture_random_state *trsp)
torture_preempt_schedule(); /* Allow test to be preempted. */
}
-static void torture_rtmutex_unlock(void) __releases(torture_rtmutex)
+static void torture_rtmutex_unlock(int tid __maybe_unused)
+__releases(torture_rtmutex)
{
rt_mutex_unlock(&torture_rtmutex);
}
@@ -505,7 +543,8 @@ static struct lock_torture_ops rtmutex_lock_ops = {
#endif
static DECLARE_RWSEM(torture_rwsem);
-static int torture_rwsem_down_write(void) __acquires(torture_rwsem)
+static int torture_rwsem_down_write(int tid __maybe_unused)
+__acquires(torture_rwsem)
{
down_write(&torture_rwsem);
return 0;
@@ -525,12 +564,14 @@ static void torture_rwsem_write_delay(struct torture_random_state *trsp)
torture_preempt_schedule(); /* Allow test to be preempted. */
}
-static void torture_rwsem_up_write(void) __releases(torture_rwsem)
+static void torture_rwsem_up_write(int tid __maybe_unused)
+__releases(torture_rwsem)
{
up_write(&torture_rwsem);
}
-static int torture_rwsem_down_read(void) __acquires(torture_rwsem)
+static int torture_rwsem_down_read(int tid __maybe_unused)
+__acquires(torture_rwsem)
{
down_read(&torture_rwsem);
return 0;
@@ -550,7 +591,8 @@ static void torture_rwsem_read_delay(struct torture_random_state *trsp)
torture_preempt_schedule(); /* Allow test to be preempted. */
}
-static void torture_rwsem_up_read(void) __releases(torture_rwsem)
+static void torture_rwsem_up_read(int tid __maybe_unused)
+__releases(torture_rwsem)
{
up_read(&torture_rwsem);
}
@@ -579,24 +621,28 @@ static void torture_percpu_rwsem_exit(void)
percpu_free_rwsem(&pcpu_rwsem);
}
-static int torture_percpu_rwsem_down_write(void) __acquires(pcpu_rwsem)
+static int torture_percpu_rwsem_down_write(int tid __maybe_unused)
+__acquires(pcpu_rwsem)
{
percpu_down_write(&pcpu_rwsem);
return 0;
}
-static void torture_percpu_rwsem_up_write(void) __releases(pcpu_rwsem)
+static void torture_percpu_rwsem_up_write(int tid __maybe_unused)
+__releases(pcpu_rwsem)
{
percpu_up_write(&pcpu_rwsem);
}
-static int torture_percpu_rwsem_down_read(void) __acquires(pcpu_rwsem)
+static int torture_percpu_rwsem_down_read(int tid __maybe_unused)
+__acquires(pcpu_rwsem)
{
percpu_down_read(&pcpu_rwsem);
return 0;
}
-static void torture_percpu_rwsem_up_read(void) __releases(pcpu_rwsem)
+static void torture_percpu_rwsem_up_read(int tid __maybe_unused)
+__releases(pcpu_rwsem)
{
percpu_up_read(&pcpu_rwsem);
}
@@ -621,6 +667,7 @@ static struct lock_torture_ops percpu_rwsem_lock_ops = {
static int lock_torture_writer(void *arg)
{
struct lock_stress_stats *lwsp = arg;
+ int tid = lwsp - cxt.lwsa;
DEFINE_TORTURE_RANDOM(rand);
VERBOSE_TOROUT_STRING("lock_torture_writer task started");
@@ -631,7 +678,7 @@ static int lock_torture_writer(void *arg)
schedule_timeout_uninterruptible(1);
cxt.cur_ops->task_boost(&rand);
- cxt.cur_ops->writelock();
+ cxt.cur_ops->writelock(tid);
if (WARN_ON_ONCE(lock_is_write_held))
lwsp->n_lock_fail++;
lock_is_write_held = true;
@@ -642,7 +689,7 @@ static int lock_torture_writer(void *arg)
cxt.cur_ops->write_delay(&rand);
lock_is_write_held = false;
WRITE_ONCE(last_lock_release, jiffies);
- cxt.cur_ops->writeunlock();
+ cxt.cur_ops->writeunlock(tid);
stutter_wait("lock_torture_writer");
} while (!torture_must_stop());
@@ -659,6 +706,7 @@ static int lock_torture_writer(void *arg)
static int lock_torture_reader(void *arg)
{
struct lock_stress_stats *lrsp = arg;
+ int tid = lrsp - cxt.lrsa;
DEFINE_TORTURE_RANDOM(rand);
VERBOSE_TOROUT_STRING("lock_torture_reader task started");
@@ -668,7 +716,7 @@ static int lock_torture_reader(void *arg)
if ((torture_random(&rand) & 0xfffff) == 0)
schedule_timeout_uninterruptible(1);
- cxt.cur_ops->readlock();
+ cxt.cur_ops->readlock(tid);
lock_is_read_held = true;
if (WARN_ON_ONCE(lock_is_write_held))
lrsp->n_lock_fail++; /* rare, but... */
@@ -676,7 +724,7 @@ static int lock_torture_reader(void *arg)
lrsp->n_lock_acquired++;
cxt.cur_ops->read_delay(&rand);
lock_is_read_held = false;
- cxt.cur_ops->readunlock();
+ cxt.cur_ops->readunlock(tid);
stutter_wait("lock_torture_reader");
} while (!torture_must_stop());
@@ -891,16 +939,16 @@ static int __init lock_torture_init(void)
goto unwind;
}
- if (cxt.cur_ops->init) {
- cxt.cur_ops->init();
- cxt.init_called = true;
- }
-
if (nwriters_stress >= 0)
cxt.nrealwriters_stress = nwriters_stress;
else
cxt.nrealwriters_stress = 2 * num_online_cpus();
+ if (cxt.cur_ops->init) {
+ cxt.cur_ops->init();
+ cxt.init_called = true;
+ }
+
#ifdef CONFIG_DEBUG_MUTEXES
if (str_has_prefix(torture_type, "mutex"))
cxt.debug_lock = true;
diff --git a/kernel/locking/mcs_spinlock.h b/kernel/locking/mcs_spinlock.h
index 5e10153b4d3c..85251d8771d9 100644
--- a/kernel/locking/mcs_spinlock.h
+++ b/kernel/locking/mcs_spinlock.h
@@ -7,7 +7,7 @@
* The MCS lock (proposed by Mellor-Crummey and Scott) is a simple spin-lock
* with the desirable properties of being fair, and with each cpu trying
* to acquire the lock spinning on a local variable.
- * It avoids expensive cache bouncings that common test-and-set spin-lock
+ * It avoids expensive cache bounces that common test-and-set spin-lock
* implementations incur.
*/
#ifndef __LINUX_MCS_SPINLOCK_H
diff --git a/kernel/locking/mutex.c b/kernel/locking/mutex.c
index 622ebdfcd083..cb6b112ce155 100644
--- a/kernel/locking/mutex.c
+++ b/kernel/locking/mutex.c
@@ -92,7 +92,7 @@ static inline unsigned long __owner_flags(unsigned long owner)
}
/*
- * Trylock variant that retuns the owning task on failure.
+ * Trylock variant that returns the owning task on failure.
*/
static inline struct task_struct *__mutex_trylock_or_owner(struct mutex *lock)
{
@@ -207,7 +207,7 @@ __mutex_add_waiter(struct mutex *lock, struct mutex_waiter *waiter,
/*
* Give up ownership to a specific task, when @task = NULL, this is equivalent
- * to a regular unlock. Sets PICKUP on a handoff, clears HANDOF, preserves
+ * to a regular unlock. Sets PICKUP on a handoff, clears HANDOFF, preserves
* WAITERS. Provides RELEASE semantics like a regular unlock, the
* __mutex_trylock() provides a matching ACQUIRE semantics for the handoff.
*/
diff --git a/kernel/locking/osq_lock.c b/kernel/locking/osq_lock.c
index 1de006ed3aa8..d5610ad52b92 100644
--- a/kernel/locking/osq_lock.c
+++ b/kernel/locking/osq_lock.c
@@ -135,7 +135,7 @@ bool osq_lock(struct optimistic_spin_queue *lock)
*/
/*
- * Wait to acquire the lock or cancelation. Note that need_resched()
+ * Wait to acquire the lock or cancellation. Note that need_resched()
* will come with an IPI, which will wake smp_cond_load_relaxed() if it
* is implemented with a monitor-wait. vcpu_is_preempted() relies on
* polling, be careful.
@@ -164,7 +164,7 @@ bool osq_lock(struct optimistic_spin_queue *lock)
/*
* We can only fail the cmpxchg() racing against an unlock(),
- * in which case we should observe @node->locked becomming
+ * in which case we should observe @node->locked becoming
* true.
*/
if (smp_load_acquire(&node->locked))
diff --git a/kernel/locking/rtmutex-debug.c b/kernel/locking/rtmutex-debug.c
deleted file mode 100644
index 36e69100e8e0..000000000000
--- a/kernel/locking/rtmutex-debug.c
+++ /dev/null
@@ -1,182 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-/*
- * RT-Mutexes: blocking mutual exclusion locks with PI support
- *
- * started by Ingo Molnar and Thomas Gleixner:
- *
- * Copyright (C) 2004-2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
- * Copyright (C) 2006 Timesys Corp., Thomas Gleixner <tglx@timesys.com>
- *
- * This code is based on the rt.c implementation in the preempt-rt tree.
- * Portions of said code are
- *
- * Copyright (C) 2004 LynuxWorks, Inc., Igor Manyilov, Bill Huey
- * Copyright (C) 2006 Esben Nielsen
- * Copyright (C) 2006 Kihon Technologies Inc.,
- * Steven Rostedt <rostedt@goodmis.org>
- *
- * See rt.c in preempt-rt for proper credits and further information
- */
-#include <linux/sched.h>
-#include <linux/sched/rt.h>
-#include <linux/sched/debug.h>
-#include <linux/delay.h>
-#include <linux/export.h>
-#include <linux/spinlock.h>
-#include <linux/kallsyms.h>
-#include <linux/syscalls.h>
-#include <linux/interrupt.h>
-#include <linux/rbtree.h>
-#include <linux/fs.h>
-#include <linux/debug_locks.h>
-
-#include "rtmutex_common.h"
-
-static void printk_task(struct task_struct *p)
-{
- if (p)
- printk("%16s:%5d [%p, %3d]", p->comm, task_pid_nr(p), p, p->prio);
- else
- printk("<none>");
-}
-
-static void printk_lock(struct rt_mutex *lock, int print_owner)
-{
- if (lock->name)
- printk(" [%p] {%s}\n",
- lock, lock->name);
- else
- printk(" [%p] {%s:%d}\n",
- lock, lock->file, lock->line);
-
- if (print_owner && rt_mutex_owner(lock)) {
- printk(".. ->owner: %p\n", lock->owner);
- printk(".. held by: ");
- printk_task(rt_mutex_owner(lock));
- printk("\n");
- }
-}
-
-void rt_mutex_debug_task_free(struct task_struct *task)
-{
- DEBUG_LOCKS_WARN_ON(!RB_EMPTY_ROOT(&task->pi_waiters.rb_root));
- DEBUG_LOCKS_WARN_ON(task->pi_blocked_on);
-}
-
-/*
- * We fill out the fields in the waiter to store the information about
- * the deadlock. We print when we return. act_waiter can be NULL in
- * case of a remove waiter operation.
- */
-void debug_rt_mutex_deadlock(enum rtmutex_chainwalk chwalk,
- struct rt_mutex_waiter *act_waiter,
- struct rt_mutex *lock)
-{
- struct task_struct *task;
-
- if (!debug_locks || chwalk == RT_MUTEX_FULL_CHAINWALK || !act_waiter)
- return;
-
- task = rt_mutex_owner(act_waiter->lock);
- if (task && task != current) {
- act_waiter->deadlock_task_pid = get_pid(task_pid(task));
- act_waiter->deadlock_lock = lock;
- }
-}
-
-void debug_rt_mutex_print_deadlock(struct rt_mutex_waiter *waiter)
-{
- struct task_struct *task;
-
- if (!waiter->deadlock_lock || !debug_locks)
- return;
-
- rcu_read_lock();
- task = pid_task(waiter->deadlock_task_pid, PIDTYPE_PID);
- if (!task) {
- rcu_read_unlock();
- return;
- }
-
- if (!debug_locks_off()) {
- rcu_read_unlock();
- return;
- }
-
- pr_warn("\n");
- pr_warn("============================================\n");
- pr_warn("WARNING: circular locking deadlock detected!\n");
- pr_warn("%s\n", print_tainted());
- pr_warn("--------------------------------------------\n");
- printk("%s/%d is deadlocking current task %s/%d\n\n",
- task->comm, task_pid_nr(task),
- current->comm, task_pid_nr(current));
-
- printk("\n1) %s/%d is trying to acquire this lock:\n",
- current->comm, task_pid_nr(current));
- printk_lock(waiter->lock, 1);
-
- printk("\n2) %s/%d is blocked on this lock:\n",
- task->comm, task_pid_nr(task));
- printk_lock(waiter->deadlock_lock, 1);
-
- debug_show_held_locks(current);
- debug_show_held_locks(task);
-
- printk("\n%s/%d's [blocked] stackdump:\n\n",
- task->comm, task_pid_nr(task));
- show_stack(task, NULL, KERN_DEFAULT);
- printk("\n%s/%d's [current] stackdump:\n\n",
- current->comm, task_pid_nr(current));
- dump_stack();
- debug_show_all_locks();
- rcu_read_unlock();
-
- printk("[ turning off deadlock detection."
- "Please report this trace. ]\n\n");
-}
-
-void debug_rt_mutex_lock(struct rt_mutex *lock)
-{
-}
-
-void debug_rt_mutex_unlock(struct rt_mutex *lock)
-{
- DEBUG_LOCKS_WARN_ON(rt_mutex_owner(lock) != current);
-}
-
-void
-debug_rt_mutex_proxy_lock(struct rt_mutex *lock, struct task_struct *powner)
-{
-}
-
-void debug_rt_mutex_proxy_unlock(struct rt_mutex *lock)
-{
- DEBUG_LOCKS_WARN_ON(!rt_mutex_owner(lock));
-}
-
-void debug_rt_mutex_init_waiter(struct rt_mutex_waiter *waiter)
-{
- memset(waiter, 0x11, sizeof(*waiter));
- waiter->deadlock_task_pid = NULL;
-}
-
-void debug_rt_mutex_free_waiter(struct rt_mutex_waiter *waiter)
-{
- put_pid(waiter->deadlock_task_pid);
- memset(waiter, 0x22, sizeof(*waiter));
-}
-
-void debug_rt_mutex_init(struct rt_mutex *lock, const char *name, struct lock_class_key *key)
-{
- /*
- * Make sure we are not reinitializing a held lock:
- */
- debug_check_no_locks_freed((void *)lock, sizeof(*lock));
- lock->name = name;
-
-#ifdef CONFIG_DEBUG_LOCK_ALLOC
- lockdep_init_map(&lock->dep_map, name, key, 0);
-#endif
-}
-
diff --git a/kernel/locking/rtmutex-debug.h b/kernel/locking/rtmutex-debug.h
deleted file mode 100644
index fc549713bba3..000000000000
--- a/kernel/locking/rtmutex-debug.h
+++ /dev/null
@@ -1,37 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-/*
- * RT-Mutexes: blocking mutual exclusion locks with PI support
- *
- * started by Ingo Molnar and Thomas Gleixner:
- *
- * Copyright (C) 2004-2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
- * Copyright (C) 2006, Timesys Corp., Thomas Gleixner <tglx@timesys.com>
- *
- * This file contains macros used solely by rtmutex.c. Debug version.
- */
-
-extern void debug_rt_mutex_init_waiter(struct rt_mutex_waiter *waiter);
-extern void debug_rt_mutex_free_waiter(struct rt_mutex_waiter *waiter);
-extern void debug_rt_mutex_init(struct rt_mutex *lock, const char *name, struct lock_class_key *key);
-extern void debug_rt_mutex_lock(struct rt_mutex *lock);
-extern void debug_rt_mutex_unlock(struct rt_mutex *lock);
-extern void debug_rt_mutex_proxy_lock(struct rt_mutex *lock,
- struct task_struct *powner);
-extern void debug_rt_mutex_proxy_unlock(struct rt_mutex *lock);
-extern void debug_rt_mutex_deadlock(enum rtmutex_chainwalk chwalk,
- struct rt_mutex_waiter *waiter,
- struct rt_mutex *lock);
-extern void debug_rt_mutex_print_deadlock(struct rt_mutex_waiter *waiter);
-# define debug_rt_mutex_reset_waiter(w) \
- do { (w)->deadlock_lock = NULL; } while (0)
-
-static inline bool debug_rt_mutex_detect_deadlock(struct rt_mutex_waiter *waiter,
- enum rtmutex_chainwalk walk)
-{
- return (waiter != NULL);
-}
-
-static inline void rt_mutex_print_deadlock(struct rt_mutex_waiter *w)
-{
- debug_rt_mutex_print_deadlock(w);
-}
diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c
index 48fff6437901..406818196a9f 100644
--- a/kernel/locking/rtmutex.c
+++ b/kernel/locking/rtmutex.c
@@ -49,7 +49,7 @@
* set this bit before looking at the lock.
*/
-static void
+static __always_inline void
rt_mutex_set_owner(struct rt_mutex *lock, struct task_struct *owner)
{
unsigned long val = (unsigned long)owner;
@@ -60,13 +60,13 @@ rt_mutex_set_owner(struct rt_mutex *lock, struct task_struct *owner)
WRITE_ONCE(lock->owner, (struct task_struct *)val);
}
-static inline void clear_rt_mutex_waiters(struct rt_mutex *lock)
+static __always_inline void clear_rt_mutex_waiters(struct rt_mutex *lock)
{
lock->owner = (struct task_struct *)
((unsigned long)lock->owner & ~RT_MUTEX_HAS_WAITERS);
}
-static void fixup_rt_mutex_waiters(struct rt_mutex *lock)
+static __always_inline void fixup_rt_mutex_waiters(struct rt_mutex *lock)
{
unsigned long owner, *p = (unsigned long *) &lock->owner;
@@ -149,7 +149,7 @@ static void fixup_rt_mutex_waiters(struct rt_mutex *lock)
* all future threads that attempt to [Rmw] the lock to the slowpath. As such
* relaxed semantics suffice.
*/
-static inline void mark_rt_mutex_waiters(struct rt_mutex *lock)
+static __always_inline void mark_rt_mutex_waiters(struct rt_mutex *lock)
{
unsigned long owner, *p = (unsigned long *) &lock->owner;
@@ -165,8 +165,8 @@ static inline void mark_rt_mutex_waiters(struct rt_mutex *lock)
* 2) Drop lock->wait_lock
* 3) Try to unlock the lock with cmpxchg
*/
-static inline bool unlock_rt_mutex_safe(struct rt_mutex *lock,
- unsigned long flags)
+static __always_inline bool unlock_rt_mutex_safe(struct rt_mutex *lock,
+ unsigned long flags)
__releases(lock->wait_lock)
{
struct task_struct *owner = rt_mutex_owner(lock);
@@ -204,7 +204,7 @@ static inline bool unlock_rt_mutex_safe(struct rt_mutex *lock,
# define rt_mutex_cmpxchg_acquire(l,c,n) (0)
# define rt_mutex_cmpxchg_release(l,c,n) (0)
-static inline void mark_rt_mutex_waiters(struct rt_mutex *lock)
+static __always_inline void mark_rt_mutex_waiters(struct rt_mutex *lock)
{
lock->owner = (struct task_struct *)
((unsigned long)lock->owner | RT_MUTEX_HAS_WAITERS);
@@ -213,8 +213,8 @@ static inline void mark_rt_mutex_waiters(struct rt_mutex *lock)
/*
* Simple slow path only version: lock->owner is protected by lock->wait_lock.
*/
-static inline bool unlock_rt_mutex_safe(struct rt_mutex *lock,
- unsigned long flags)
+static __always_inline bool unlock_rt_mutex_safe(struct rt_mutex *lock,
+ unsigned long flags)
__releases(lock->wait_lock)
{
lock->owner = NULL;
@@ -229,9 +229,8 @@ static inline bool unlock_rt_mutex_safe(struct rt_mutex *lock,
#define task_to_waiter(p) \
&(struct rt_mutex_waiter){ .prio = (p)->prio, .deadline = (p)->dl.deadline }
-static inline int
-rt_mutex_waiter_less(struct rt_mutex_waiter *left,
- struct rt_mutex_waiter *right)
+static __always_inline int rt_mutex_waiter_less(struct rt_mutex_waiter *left,
+ struct rt_mutex_waiter *right)
{
if (left->prio < right->prio)
return 1;
@@ -248,9 +247,8 @@ rt_mutex_waiter_less(struct rt_mutex_waiter *left,
return 0;
}
-static inline int
-rt_mutex_waiter_equal(struct rt_mutex_waiter *left,
- struct rt_mutex_waiter *right)
+static __always_inline int rt_mutex_waiter_equal(struct rt_mutex_waiter *left,
+ struct rt_mutex_waiter *right)
{
if (left->prio != right->prio)
return 0;
@@ -270,18 +268,18 @@ rt_mutex_waiter_equal(struct rt_mutex_waiter *left,
#define __node_2_waiter(node) \
rb_entry((node), struct rt_mutex_waiter, tree_entry)
-static inline bool __waiter_less(struct rb_node *a, const struct rb_node *b)
+static __always_inline bool __waiter_less(struct rb_node *a, const struct rb_node *b)
{
return rt_mutex_waiter_less(__node_2_waiter(a), __node_2_waiter(b));
}
-static void
+static __always_inline void
rt_mutex_enqueue(struct rt_mutex *lock, struct rt_mutex_waiter *waiter)
{
rb_add_cached(&waiter->tree_entry, &lock->waiters, __waiter_less);
}
-static void
+static __always_inline void
rt_mutex_dequeue(struct rt_mutex *lock, struct rt_mutex_waiter *waiter)
{
if (RB_EMPTY_NODE(&waiter->tree_entry))
@@ -294,18 +292,19 @@ rt_mutex_dequeue(struct rt_mutex *lock, struct rt_mutex_waiter *waiter)
#define __node_2_pi_waiter(node) \
rb_entry((node), struct rt_mutex_waiter, pi_tree_entry)
-static inline bool __pi_waiter_less(struct rb_node *a, const struct rb_node *b)
+static __always_inline bool
+__pi_waiter_less(struct rb_node *a, const struct rb_node *b)
{
return rt_mutex_waiter_less(__node_2_pi_waiter(a), __node_2_pi_waiter(b));
}
-static void
+static __always_inline void
rt_mutex_enqueue_pi(struct task_struct *task, struct rt_mutex_waiter *waiter)
{
rb_add_cached(&waiter->pi_tree_entry, &task->pi_waiters, __pi_waiter_less);
}
-static void
+static __always_inline void
rt_mutex_dequeue_pi(struct task_struct *task, struct rt_mutex_waiter *waiter)
{
if (RB_EMPTY_NODE(&waiter->pi_tree_entry))
@@ -315,7 +314,7 @@ rt_mutex_dequeue_pi(struct task_struct *task, struct rt_mutex_waiter *waiter)
RB_CLEAR_NODE(&waiter->pi_tree_entry);
}
-static void rt_mutex_adjust_prio(struct task_struct *p)
+static __always_inline void rt_mutex_adjust_prio(struct task_struct *p)
{
struct task_struct *pi_task = NULL;
@@ -340,17 +339,13 @@ static void rt_mutex_adjust_prio(struct task_struct *p)
* deadlock detection is disabled independent of the detect argument
* and the config settings.
*/
-static bool rt_mutex_cond_detect_deadlock(struct rt_mutex_waiter *waiter,
- enum rtmutex_chainwalk chwalk)
+static __always_inline bool
+rt_mutex_cond_detect_deadlock(struct rt_mutex_waiter *waiter,
+ enum rtmutex_chainwalk chwalk)
{
- /*
- * This is just a wrapper function for the following call,
- * because debug_rt_mutex_detect_deadlock() smells like a magic
- * debug feature and I wanted to keep the cond function in the
- * main source file along with the comments instead of having
- * two of the same in the headers.
- */
- return debug_rt_mutex_detect_deadlock(waiter, chwalk);
+ if (IS_ENABLED(CONFIG_DEBUG_RT_MUTEX))
+ return waiter != NULL;
+ return chwalk == RT_MUTEX_FULL_CHAINWALK;
}
/*
@@ -358,7 +353,7 @@ static bool rt_mutex_cond_detect_deadlock(struct rt_mutex_waiter *waiter,
*/
int max_lock_depth = 1024;
-static inline struct rt_mutex *task_blocked_on_lock(struct task_struct *p)
+static __always_inline struct rt_mutex *task_blocked_on_lock(struct task_struct *p)
{
return p->pi_blocked_on ? p->pi_blocked_on->lock : NULL;
}
@@ -426,12 +421,12 @@ static inline struct rt_mutex *task_blocked_on_lock(struct task_struct *p)
* unlock(lock->wait_lock); release [L]
* goto again;
*/
-static int rt_mutex_adjust_prio_chain(struct task_struct *task,
- enum rtmutex_chainwalk chwalk,
- struct rt_mutex *orig_lock,
- struct rt_mutex *next_lock,
- struct rt_mutex_waiter *orig_waiter,
- struct task_struct *top_task)
+static int __sched rt_mutex_adjust_prio_chain(struct task_struct *task,
+ enum rtmutex_chainwalk chwalk,
+ struct rt_mutex *orig_lock,
+ struct rt_mutex *next_lock,
+ struct rt_mutex_waiter *orig_waiter,
+ struct task_struct *top_task)
{
struct rt_mutex_waiter *waiter, *top_waiter = orig_waiter;
struct rt_mutex_waiter *prerequeue_top_waiter;
@@ -579,7 +574,6 @@ static int rt_mutex_adjust_prio_chain(struct task_struct *task,
* walk, we detected a deadlock.
*/
if (lock == orig_lock || rt_mutex_owner(lock) == top_task) {
- debug_rt_mutex_deadlock(chwalk, orig_waiter, lock);
raw_spin_unlock(&lock->wait_lock);
ret = -EDEADLK;
goto out_unlock_pi;
@@ -706,7 +700,7 @@ static int rt_mutex_adjust_prio_chain(struct task_struct *task,
} else if (prerequeue_top_waiter == waiter) {
/*
* The waiter was the top waiter on the lock, but is
- * no longer the top prority waiter. Replace waiter in
+ * no longer the top priority waiter. Replace waiter in
* the owner tasks pi waiters tree with the new top
* (highest priority) waiter and adjust the priority
* of the owner.
@@ -784,8 +778,9 @@ static int rt_mutex_adjust_prio_chain(struct task_struct *task,
* @waiter: The waiter that is queued to the lock's wait tree if the
* callsite called task_blocked_on_lock(), otherwise NULL
*/
-static int try_to_take_rt_mutex(struct rt_mutex *lock, struct task_struct *task,
- struct rt_mutex_waiter *waiter)
+static int __sched
+try_to_take_rt_mutex(struct rt_mutex *lock, struct task_struct *task,
+ struct rt_mutex_waiter *waiter)
{
lockdep_assert_held(&lock->wait_lock);
@@ -886,9 +881,6 @@ static int try_to_take_rt_mutex(struct rt_mutex *lock, struct task_struct *task,
raw_spin_unlock(&task->pi_lock);
takeit:
- /* We got the lock. */
- debug_rt_mutex_lock(lock);
-
/*
* This either preserves the RT_MUTEX_HAS_WAITERS bit if there
* are still waiters or clears it.
@@ -905,10 +897,10 @@ takeit:
*
* This must be called with lock->wait_lock held and interrupts disabled
*/
-static int task_blocks_on_rt_mutex(struct rt_mutex *lock,
- struct rt_mutex_waiter *waiter,
- struct task_struct *task,
- enum rtmutex_chainwalk chwalk)
+static int __sched task_blocks_on_rt_mutex(struct rt_mutex *lock,
+ struct rt_mutex_waiter *waiter,
+ struct task_struct *task,
+ enum rtmutex_chainwalk chwalk)
{
struct task_struct *owner = rt_mutex_owner(lock);
struct rt_mutex_waiter *top_waiter = waiter;
@@ -994,8 +986,8 @@ static int task_blocks_on_rt_mutex(struct rt_mutex *lock,
*
* Called with lock->wait_lock held and interrupts disabled.
*/
-static void mark_wakeup_next_waiter(struct wake_q_head *wake_q,
- struct rt_mutex *lock)
+static void __sched mark_wakeup_next_waiter(struct wake_q_head *wake_q,
+ struct rt_mutex *lock)
{
struct rt_mutex_waiter *waiter;
@@ -1044,8 +1036,8 @@ static void mark_wakeup_next_waiter(struct wake_q_head *wake_q,
* Must be called with lock->wait_lock held and interrupts disabled. I must
* have just failed to try_to_take_rt_mutex().
*/
-static void remove_waiter(struct rt_mutex *lock,
- struct rt_mutex_waiter *waiter)
+static void __sched remove_waiter(struct rt_mutex *lock,
+ struct rt_mutex_waiter *waiter)
{
bool is_top_waiter = (waiter == rt_mutex_top_waiter(lock));
struct task_struct *owner = rt_mutex_owner(lock);
@@ -1102,7 +1094,7 @@ static void remove_waiter(struct rt_mutex *lock,
*
* Called from sched_setscheduler
*/
-void rt_mutex_adjust_pi(struct task_struct *task)
+void __sched rt_mutex_adjust_pi(struct task_struct *task)
{
struct rt_mutex_waiter *waiter;
struct rt_mutex *next_lock;
@@ -1125,7 +1117,7 @@ void rt_mutex_adjust_pi(struct task_struct *task)
next_lock, NULL, task);
}
-void rt_mutex_init_waiter(struct rt_mutex_waiter *waiter)
+void __sched rt_mutex_init_waiter(struct rt_mutex_waiter *waiter)
{
debug_rt_mutex_init_waiter(waiter);
RB_CLEAR_NODE(&waiter->pi_tree_entry);
@@ -1143,10 +1135,9 @@ void rt_mutex_init_waiter(struct rt_mutex_waiter *waiter)
*
* Must be called with lock->wait_lock held and interrupts disabled
*/
-static int __sched
-__rt_mutex_slowlock(struct rt_mutex *lock, int state,
- struct hrtimer_sleeper *timeout,
- struct rt_mutex_waiter *waiter)
+static int __sched __rt_mutex_slowlock(struct rt_mutex *lock, int state,
+ struct hrtimer_sleeper *timeout,
+ struct rt_mutex_waiter *waiter)
{
int ret = 0;
@@ -1155,24 +1146,17 @@ __rt_mutex_slowlock(struct rt_mutex *lock, int state,
if (try_to_take_rt_mutex(lock, current, waiter))
break;
- /*
- * TASK_INTERRUPTIBLE checks for signals and
- * timeout. Ignored otherwise.
- */
- if (likely(state == TASK_INTERRUPTIBLE)) {
- /* Signal pending? */
- if (signal_pending(current))
- ret = -EINTR;
- if (timeout && !timeout->task)
- ret = -ETIMEDOUT;
- if (ret)
- break;
+ if (timeout && !timeout->task) {
+ ret = -ETIMEDOUT;
+ break;
+ }
+ if (signal_pending_state(state, current)) {
+ ret = -EINTR;
+ break;
}
raw_spin_unlock_irq(&lock->wait_lock);
- debug_rt_mutex_print_deadlock(waiter);
-
schedule();
raw_spin_lock_irq(&lock->wait_lock);
@@ -1183,8 +1167,8 @@ __rt_mutex_slowlock(struct rt_mutex *lock, int state,
return ret;
}
-static void rt_mutex_handle_deadlock(int res, int detect_deadlock,
- struct rt_mutex_waiter *w)
+static void __sched rt_mutex_handle_deadlock(int res, int detect_deadlock,
+ struct rt_mutex_waiter *w)
{
/*
* If the result is not -EDEADLOCK or the caller requested
@@ -1194,9 +1178,9 @@ static void rt_mutex_handle_deadlock(int res, int detect_deadlock,
return;
/*
- * Yell lowdly and stop the task right here.
+ * Yell loudly and stop the task right here.
*/
- rt_mutex_print_deadlock(w);
+ WARN(1, "rtmutex deadlock detected\n");
while (1) {
set_current_state(TASK_INTERRUPTIBLE);
schedule();
@@ -1206,10 +1190,9 @@ static void rt_mutex_handle_deadlock(int res, int detect_deadlock,
/*
* Slow path lock function:
*/
-static int __sched
-rt_mutex_slowlock(struct rt_mutex *lock, int state,
- struct hrtimer_sleeper *timeout,
- enum rtmutex_chainwalk chwalk)
+static int __sched rt_mutex_slowlock(struct rt_mutex *lock, int state,
+ struct hrtimer_sleeper *timeout,
+ enum rtmutex_chainwalk chwalk)
{
struct rt_mutex_waiter waiter;
unsigned long flags;
@@ -1268,7 +1251,7 @@ rt_mutex_slowlock(struct rt_mutex *lock, int state,
return ret;
}
-static inline int __rt_mutex_slowtrylock(struct rt_mutex *lock)
+static int __sched __rt_mutex_slowtrylock(struct rt_mutex *lock)
{
int ret = try_to_take_rt_mutex(lock, current, NULL);
@@ -1284,7 +1267,7 @@ static inline int __rt_mutex_slowtrylock(struct rt_mutex *lock)
/*
* Slow path try-lock function:
*/
-static inline int rt_mutex_slowtrylock(struct rt_mutex *lock)
+static int __sched rt_mutex_slowtrylock(struct rt_mutex *lock)
{
unsigned long flags;
int ret;
@@ -1311,13 +1294,24 @@ static inline int rt_mutex_slowtrylock(struct rt_mutex *lock)
}
/*
+ * Performs the wakeup of the top-waiter and re-enables preemption.
+ */
+void __sched rt_mutex_postunlock(struct wake_q_head *wake_q)
+{
+ wake_up_q(wake_q);
+
+ /* Pairs with preempt_disable() in mark_wakeup_next_waiter() */
+ preempt_enable();
+}
+
+/*
* Slow path to release a rt-mutex.
*
* Return whether the current task needs to call rt_mutex_postunlock().
*/
-static bool __sched rt_mutex_slowunlock(struct rt_mutex *lock,
- struct wake_q_head *wake_q)
+static void __sched rt_mutex_slowunlock(struct rt_mutex *lock)
{
+ DEFINE_WAKE_Q(wake_q);
unsigned long flags;
/* irqsave required to support early boot calls */
@@ -1359,7 +1353,7 @@ static bool __sched rt_mutex_slowunlock(struct rt_mutex *lock,
while (!rt_mutex_has_waiters(lock)) {
/* Drops lock->wait_lock ! */
if (unlock_rt_mutex_safe(lock, flags) == true)
- return false;
+ return;
/* Relock the rtmutex and try again */
raw_spin_lock_irqsave(&lock->wait_lock, flags);
}
@@ -1370,10 +1364,10 @@ static bool __sched rt_mutex_slowunlock(struct rt_mutex *lock,
*
* Queue the next waiter for wakeup once we release the wait_lock.
*/
- mark_wakeup_next_waiter(wake_q, lock);
+ mark_wakeup_next_waiter(&wake_q, lock);
raw_spin_unlock_irqrestore(&lock->wait_lock, flags);
- return true; /* call rt_mutex_postunlock() */
+ rt_mutex_postunlock(&wake_q);
}
/*
@@ -1382,74 +1376,21 @@ static bool __sched rt_mutex_slowunlock(struct rt_mutex *lock,
* The atomic acquire/release ops are compiled away, when either the
* architecture does not support cmpxchg or when debugging is enabled.
*/
-static inline int
-rt_mutex_fastlock(struct rt_mutex *lock, int state,
- int (*slowfn)(struct rt_mutex *lock, int state,
- struct hrtimer_sleeper *timeout,
- enum rtmutex_chainwalk chwalk))
-{
- if (likely(rt_mutex_cmpxchg_acquire(lock, NULL, current)))
- return 0;
-
- return slowfn(lock, state, NULL, RT_MUTEX_MIN_CHAINWALK);
-}
-
-static inline int
-rt_mutex_timed_fastlock(struct rt_mutex *lock, int state,
- struct hrtimer_sleeper *timeout,
- enum rtmutex_chainwalk chwalk,
- int (*slowfn)(struct rt_mutex *lock, int state,
- struct hrtimer_sleeper *timeout,
- enum rtmutex_chainwalk chwalk))
+static __always_inline int __rt_mutex_lock(struct rt_mutex *lock, long state,
+ unsigned int subclass)
{
- if (chwalk == RT_MUTEX_MIN_CHAINWALK &&
- likely(rt_mutex_cmpxchg_acquire(lock, NULL, current)))
- return 0;
+ int ret;
- return slowfn(lock, state, timeout, chwalk);
-}
+ might_sleep();
+ mutex_acquire(&lock->dep_map, subclass, 0, _RET_IP_);
-static inline int
-rt_mutex_fasttrylock(struct rt_mutex *lock,
- int (*slowfn)(struct rt_mutex *lock))
-{
if (likely(rt_mutex_cmpxchg_acquire(lock, NULL, current)))
- return 1;
-
- return slowfn(lock);
-}
-
-/*
- * Performs the wakeup of the top-waiter and re-enables preemption.
- */
-void rt_mutex_postunlock(struct wake_q_head *wake_q)
-{
- wake_up_q(wake_q);
-
- /* Pairs with preempt_disable() in rt_mutex_slowunlock() */
- preempt_enable();
-}
-
-static inline void
-rt_mutex_fastunlock(struct rt_mutex *lock,
- bool (*slowfn)(struct rt_mutex *lock,
- struct wake_q_head *wqh))
-{
- DEFINE_WAKE_Q(wake_q);
-
- if (likely(rt_mutex_cmpxchg_release(lock, current, NULL)))
- return;
-
- if (slowfn(lock, &wake_q))
- rt_mutex_postunlock(&wake_q);
-}
-
-static inline void __rt_mutex_lock(struct rt_mutex *lock, unsigned int subclass)
-{
- might_sleep();
+ return 0;
- mutex_acquire(&lock->dep_map, subclass, 0, _RET_IP_);
- rt_mutex_fastlock(lock, TASK_UNINTERRUPTIBLE, rt_mutex_slowlock);
+ ret = rt_mutex_slowlock(lock, state, NULL, RT_MUTEX_MIN_CHAINWALK);
+ if (ret)
+ mutex_release(&lock->dep_map, _RET_IP_);
+ return ret;
}
#ifdef CONFIG_DEBUG_LOCK_ALLOC
@@ -1461,7 +1402,7 @@ static inline void __rt_mutex_lock(struct rt_mutex *lock, unsigned int subclass)
*/
void __sched rt_mutex_lock_nested(struct rt_mutex *lock, unsigned int subclass)
{
- __rt_mutex_lock(lock, subclass);
+ __rt_mutex_lock(lock, TASK_UNINTERRUPTIBLE, subclass);
}
EXPORT_SYMBOL_GPL(rt_mutex_lock_nested);
@@ -1474,7 +1415,7 @@ EXPORT_SYMBOL_GPL(rt_mutex_lock_nested);
*/
void __sched rt_mutex_lock(struct rt_mutex *lock)
{
- __rt_mutex_lock(lock, 0);
+ __rt_mutex_lock(lock, TASK_UNINTERRUPTIBLE, 0);
}
EXPORT_SYMBOL_GPL(rt_mutex_lock);
#endif
@@ -1490,82 +1431,37 @@ EXPORT_SYMBOL_GPL(rt_mutex_lock);
*/
int __sched rt_mutex_lock_interruptible(struct rt_mutex *lock)
{
- int ret;
-
- might_sleep();
-
- mutex_acquire(&lock->dep_map, 0, 0, _RET_IP_);
- ret = rt_mutex_fastlock(lock, TASK_INTERRUPTIBLE, rt_mutex_slowlock);
- if (ret)
- mutex_release(&lock->dep_map, _RET_IP_);
-
- return ret;
+ return __rt_mutex_lock(lock, TASK_INTERRUPTIBLE, 0);
}
EXPORT_SYMBOL_GPL(rt_mutex_lock_interruptible);
-/*
- * Futex variant, must not use fastpath.
- */
-int __sched rt_mutex_futex_trylock(struct rt_mutex *lock)
-{
- return rt_mutex_slowtrylock(lock);
-}
-
-int __sched __rt_mutex_futex_trylock(struct rt_mutex *lock)
-{
- return __rt_mutex_slowtrylock(lock);
-}
-
-/**
- * rt_mutex_timed_lock - lock a rt_mutex interruptible
- * the timeout structure is provided
- * by the caller
- *
- * @lock: the rt_mutex to be locked
- * @timeout: timeout structure or NULL (no timeout)
- *
- * Returns:
- * 0 on success
- * -EINTR when interrupted by a signal
- * -ETIMEDOUT when the timeout expired
- */
-int
-rt_mutex_timed_lock(struct rt_mutex *lock, struct hrtimer_sleeper *timeout)
-{
- int ret;
-
- might_sleep();
-
- mutex_acquire(&lock->dep_map, 0, 0, _RET_IP_);
- ret = rt_mutex_timed_fastlock(lock, TASK_INTERRUPTIBLE, timeout,
- RT_MUTEX_MIN_CHAINWALK,
- rt_mutex_slowlock);
- if (ret)
- mutex_release(&lock->dep_map, _RET_IP_);
-
- return ret;
-}
-EXPORT_SYMBOL_GPL(rt_mutex_timed_lock);
-
/**
* rt_mutex_trylock - try to lock a rt_mutex
*
* @lock: the rt_mutex to be locked
*
- * This function can only be called in thread context. It's safe to
- * call it from atomic regions, but not from hard interrupt or soft
- * interrupt context.
+ * This function can only be called in thread context. It's safe to call it
+ * from atomic regions, but not from hard or soft interrupt context.
*
- * Returns 1 on success and 0 on contention
+ * Returns:
+ * 1 on success
+ * 0 on contention
*/
int __sched rt_mutex_trylock(struct rt_mutex *lock)
{
int ret;
- if (WARN_ON_ONCE(in_irq() || in_nmi() || in_serving_softirq()))
+ if (IS_ENABLED(CONFIG_DEBUG_RT_MUTEXES) && WARN_ON_ONCE(!in_task()))
return 0;
- ret = rt_mutex_fasttrylock(lock, rt_mutex_slowtrylock);
+ /*
+ * No lockdep annotation required because lockdep disables the fast
+ * path.
+ */
+ if (likely(rt_mutex_cmpxchg_acquire(lock, NULL, current)))
+ return 1;
+
+ ret = rt_mutex_slowtrylock(lock);
if (ret)
mutex_acquire(&lock->dep_map, 0, 1, _RET_IP_);
@@ -1581,10 +1477,26 @@ EXPORT_SYMBOL_GPL(rt_mutex_trylock);
void __sched rt_mutex_unlock(struct rt_mutex *lock)
{
mutex_release(&lock->dep_map, _RET_IP_);
- rt_mutex_fastunlock(lock, rt_mutex_slowunlock);
+ if (likely(rt_mutex_cmpxchg_release(lock, current, NULL)))
+ return;
+
+ rt_mutex_slowunlock(lock);
}
EXPORT_SYMBOL_GPL(rt_mutex_unlock);
+/*
+ * Futex variants, must not use fastpath.
+ */
+int __sched rt_mutex_futex_trylock(struct rt_mutex *lock)
+{
+ return rt_mutex_slowtrylock(lock);
+}
+
+int __sched __rt_mutex_futex_trylock(struct rt_mutex *lock)
+{
+ return __rt_mutex_slowtrylock(lock);
+}
+
/**
* __rt_mutex_futex_unlock - Futex variant, that since futex variants
* do not use the fast-path, can be simple and will not need to retry.
@@ -1593,7 +1505,7 @@ EXPORT_SYMBOL_GPL(rt_mutex_unlock);
* @wake_q: The wake queue head from which to get the next lock waiter
*/
bool __sched __rt_mutex_futex_unlock(struct rt_mutex *lock,
- struct wake_q_head *wake_q)
+ struct wake_q_head *wake_q)
{
lockdep_assert_held(&lock->wait_lock);
@@ -1630,23 +1542,6 @@ void __sched rt_mutex_futex_unlock(struct rt_mutex *lock)
}
/**
- * rt_mutex_destroy - mark a mutex unusable
- * @lock: the mutex to be destroyed
- *
- * This function marks the mutex uninitialized, and any subsequent
- * use of the mutex is forbidden. The mutex must not be locked when
- * this function is called.
- */
-void rt_mutex_destroy(struct rt_mutex *lock)
-{
- WARN_ON(rt_mutex_is_locked(lock));
-#ifdef CONFIG_DEBUG_RT_MUTEXES
- lock->magic = NULL;
-#endif
-}
-EXPORT_SYMBOL_GPL(rt_mutex_destroy);
-
-/**
* __rt_mutex_init - initialize the rt_mutex
*
* @lock: The rt_mutex to be initialized
@@ -1657,15 +1552,13 @@ EXPORT_SYMBOL_GPL(rt_mutex_destroy);
*
* Initializing of a locked rt_mutex is not allowed
*/
-void __rt_mutex_init(struct rt_mutex *lock, const char *name,
+void __sched __rt_mutex_init(struct rt_mutex *lock, const char *name,
struct lock_class_key *key)
{
- lock->owner = NULL;
- raw_spin_lock_init(&lock->wait_lock);
- lock->waiters = RB_ROOT_CACHED;
+ debug_check_no_locks_freed((void *)lock, sizeof(*lock));
+ lockdep_init_map(&lock->dep_map, name, key, 0);
- if (name && key)
- debug_rt_mutex_init(lock, name, key);
+ __rt_mutex_basic_init(lock);
}
EXPORT_SYMBOL_GPL(__rt_mutex_init);
@@ -1683,11 +1576,10 @@ EXPORT_SYMBOL_GPL(__rt_mutex_init);
* possible at this point because the pi_state which contains the rtmutex
* is not yet visible to other tasks.
*/
-void rt_mutex_init_proxy_locked(struct rt_mutex *lock,
- struct task_struct *proxy_owner)
+void __sched rt_mutex_init_proxy_locked(struct rt_mutex *lock,
+ struct task_struct *proxy_owner)
{
- __rt_mutex_init(lock, NULL, NULL);
- debug_rt_mutex_proxy_lock(lock, proxy_owner);
+ __rt_mutex_basic_init(lock);
rt_mutex_set_owner(lock, proxy_owner);
}
@@ -1703,7 +1595,7 @@ void rt_mutex_init_proxy_locked(struct rt_mutex *lock,
* possible because it belongs to the pi_state which is about to be freed
* and it is not longer visible to other tasks.
*/
-void rt_mutex_proxy_unlock(struct rt_mutex *lock)
+void __sched rt_mutex_proxy_unlock(struct rt_mutex *lock)
{
debug_rt_mutex_proxy_unlock(lock);
rt_mutex_set_owner(lock, NULL);
@@ -1728,9 +1620,9 @@ void rt_mutex_proxy_unlock(struct rt_mutex *lock)
*
* Special API call for PI-futex support.
*/
-int __rt_mutex_start_proxy_lock(struct rt_mutex *lock,
- struct rt_mutex_waiter *waiter,
- struct task_struct *task)
+int __sched __rt_mutex_start_proxy_lock(struct rt_mutex *lock,
+ struct rt_mutex_waiter *waiter,
+ struct task_struct *task)
{
int ret;
@@ -1753,8 +1645,6 @@ int __rt_mutex_start_proxy_lock(struct rt_mutex *lock,
ret = 0;
}
- debug_rt_mutex_print_deadlock(waiter);
-
return ret;
}
@@ -1777,9 +1667,9 @@ int __rt_mutex_start_proxy_lock(struct rt_mutex *lock,
*
* Special API call for PI-futex support.
*/
-int rt_mutex_start_proxy_lock(struct rt_mutex *lock,
- struct rt_mutex_waiter *waiter,
- struct task_struct *task)
+int __sched rt_mutex_start_proxy_lock(struct rt_mutex *lock,
+ struct rt_mutex_waiter *waiter,
+ struct task_struct *task)
{
int ret;
@@ -1793,26 +1683,6 @@ int rt_mutex_start_proxy_lock(struct rt_mutex *lock,
}
/**
- * rt_mutex_next_owner - return the next owner of the lock
- *
- * @lock: the rt lock query
- *
- * Returns the next owner of the lock or NULL
- *
- * Caller has to serialize against other accessors to the lock
- * itself.
- *
- * Special API call for PI-futex support
- */
-struct task_struct *rt_mutex_next_owner(struct rt_mutex *lock)
-{
- if (!rt_mutex_has_waiters(lock))
- return NULL;
-
- return rt_mutex_top_waiter(lock)->task;
-}
-
-/**
* rt_mutex_wait_proxy_lock() - Wait for lock acquisition
* @lock: the rt_mutex we were woken on
* @to: the timeout, null if none. hrtimer should already have
@@ -1829,9 +1699,9 @@ struct task_struct *rt_mutex_next_owner(struct rt_mutex *lock)
*
* Special API call for PI-futex support
*/
-int rt_mutex_wait_proxy_lock(struct rt_mutex *lock,
- struct hrtimer_sleeper *to,
- struct rt_mutex_waiter *waiter)
+int __sched rt_mutex_wait_proxy_lock(struct rt_mutex *lock,
+ struct hrtimer_sleeper *to,
+ struct rt_mutex_waiter *waiter)
{
int ret;
@@ -1869,8 +1739,8 @@ int rt_mutex_wait_proxy_lock(struct rt_mutex *lock,
*
* Special API call for PI-futex support
*/
-bool rt_mutex_cleanup_proxy_lock(struct rt_mutex *lock,
- struct rt_mutex_waiter *waiter)
+bool __sched rt_mutex_cleanup_proxy_lock(struct rt_mutex *lock,
+ struct rt_mutex_waiter *waiter)
{
bool cleanup = false;
@@ -1905,3 +1775,11 @@ bool rt_mutex_cleanup_proxy_lock(struct rt_mutex *lock,
return cleanup;
}
+
+#ifdef CONFIG_DEBUG_RT_MUTEXES
+void rt_mutex_debug_task_free(struct task_struct *task)
+{
+ DEBUG_LOCKS_WARN_ON(!RB_EMPTY_ROOT(&task->pi_waiters.rb_root));
+ DEBUG_LOCKS_WARN_ON(task->pi_blocked_on);
+}
+#endif
diff --git a/kernel/locking/rtmutex.h b/kernel/locking/rtmutex.h
deleted file mode 100644
index 732f96abf462..000000000000
--- a/kernel/locking/rtmutex.h
+++ /dev/null
@@ -1,35 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-/*
- * RT-Mutexes: blocking mutual exclusion locks with PI support
- *
- * started by Ingo Molnar and Thomas Gleixner:
- *
- * Copyright (C) 2004-2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
- * Copyright (C) 2006, Timesys Corp., Thomas Gleixner <tglx@timesys.com>
- *
- * This file contains macros used solely by rtmutex.c.
- * Non-debug version.
- */
-
-#define rt_mutex_deadlock_check(l) (0)
-#define debug_rt_mutex_init_waiter(w) do { } while (0)
-#define debug_rt_mutex_free_waiter(w) do { } while (0)
-#define debug_rt_mutex_lock(l) do { } while (0)
-#define debug_rt_mutex_proxy_lock(l,p) do { } while (0)
-#define debug_rt_mutex_proxy_unlock(l) do { } while (0)
-#define debug_rt_mutex_unlock(l) do { } while (0)
-#define debug_rt_mutex_init(m, n, k) do { } while (0)
-#define debug_rt_mutex_deadlock(d, a ,l) do { } while (0)
-#define debug_rt_mutex_print_deadlock(w) do { } while (0)
-#define debug_rt_mutex_reset_waiter(w) do { } while (0)
-
-static inline void rt_mutex_print_deadlock(struct rt_mutex_waiter *w)
-{
- WARN(1, "rtmutex deadlock detected\n");
-}
-
-static inline bool debug_rt_mutex_detect_deadlock(struct rt_mutex_waiter *w,
- enum rtmutex_chainwalk walk)
-{
- return walk == RT_MUTEX_FULL_CHAINWALK;
-}
diff --git a/kernel/locking/rtmutex_common.h b/kernel/locking/rtmutex_common.h
index ca6fb489007b..a90c22abdbca 100644
--- a/kernel/locking/rtmutex_common.h
+++ b/kernel/locking/rtmutex_common.h
@@ -13,6 +13,7 @@
#ifndef __KERNEL_RTMUTEX_COMMON_H
#define __KERNEL_RTMUTEX_COMMON_H
+#include <linux/debug_locks.h>
#include <linux/rtmutex.h>
#include <linux/sched/wake_q.h>
@@ -23,34 +24,30 @@
* @tree_entry: pi node to enqueue into the mutex waiters tree
* @pi_tree_entry: pi node to enqueue into the mutex owner waiters tree
* @task: task reference to the blocked task
+ * @lock: Pointer to the rt_mutex on which the waiter blocks
+ * @prio: Priority of the waiter
+ * @deadline: Deadline of the waiter if applicable
*/
struct rt_mutex_waiter {
- struct rb_node tree_entry;
- struct rb_node pi_tree_entry;
+ struct rb_node tree_entry;
+ struct rb_node pi_tree_entry;
struct task_struct *task;
struct rt_mutex *lock;
-#ifdef CONFIG_DEBUG_RT_MUTEXES
- unsigned long ip;
- struct pid *deadlock_task_pid;
- struct rt_mutex *deadlock_lock;
-#endif
- int prio;
- u64 deadline;
+ int prio;
+ u64 deadline;
};
/*
- * Various helpers to access the waiters-tree:
+ * Must be guarded because this header is included from rcu/tree_plugin.h
+ * unconditionally.
*/
-
#ifdef CONFIG_RT_MUTEXES
-
static inline int rt_mutex_has_waiters(struct rt_mutex *lock)
{
return !RB_EMPTY_ROOT(&lock->waiters.rb_root);
}
-static inline struct rt_mutex_waiter *
-rt_mutex_top_waiter(struct rt_mutex *lock)
+static inline struct rt_mutex_waiter *rt_mutex_top_waiter(struct rt_mutex *lock)
{
struct rb_node *leftmost = rb_first_cached(&lock->waiters);
struct rt_mutex_waiter *w = NULL;
@@ -67,42 +64,12 @@ static inline int task_has_pi_waiters(struct task_struct *p)
return !RB_EMPTY_ROOT(&p->pi_waiters.rb_root);
}
-static inline struct rt_mutex_waiter *
-task_top_pi_waiter(struct task_struct *p)
-{
- return rb_entry(p->pi_waiters.rb_leftmost,
- struct rt_mutex_waiter, pi_tree_entry);
-}
-
-#else
-
-static inline int rt_mutex_has_waiters(struct rt_mutex *lock)
-{
- return false;
-}
-
-static inline struct rt_mutex_waiter *
-rt_mutex_top_waiter(struct rt_mutex *lock)
+static inline struct rt_mutex_waiter *task_top_pi_waiter(struct task_struct *p)
{
- return NULL;
-}
-
-static inline int task_has_pi_waiters(struct task_struct *p)
-{
- return false;
+ return rb_entry(p->pi_waiters.rb_leftmost, struct rt_mutex_waiter,
+ pi_tree_entry);
}
-static inline struct rt_mutex_waiter *
-task_top_pi_waiter(struct task_struct *p)
-{
- return NULL;
-}
-
-#endif
-
-/*
- * lock->owner state tracking:
- */
#define RT_MUTEX_HAS_WAITERS 1UL
static inline struct task_struct *rt_mutex_owner(struct rt_mutex *lock)
@@ -111,6 +78,13 @@ static inline struct task_struct *rt_mutex_owner(struct rt_mutex *lock)
return (struct task_struct *) (owner & ~RT_MUTEX_HAS_WAITERS);
}
+#else /* CONFIG_RT_MUTEXES */
+/* Used in rcu/tree_plugin.h */
+static inline struct task_struct *rt_mutex_owner(struct rt_mutex *lock)
+{
+ return NULL;
+}
+#endif /* !CONFIG_RT_MUTEXES */
/*
* Constants for rt mutex functions which have a selectable deadlock
@@ -127,10 +101,16 @@ enum rtmutex_chainwalk {
RT_MUTEX_FULL_CHAINWALK,
};
+static inline void __rt_mutex_basic_init(struct rt_mutex *lock)
+{
+ lock->owner = NULL;
+ raw_spin_lock_init(&lock->wait_lock);
+ lock->waiters = RB_ROOT_CACHED;
+}
+
/*
* PI-futex support (proxy locking functions, etc.):
*/
-extern struct task_struct *rt_mutex_next_owner(struct rt_mutex *lock);
extern void rt_mutex_init_proxy_locked(struct rt_mutex *lock,
struct task_struct *proxy_owner);
extern void rt_mutex_proxy_unlock(struct rt_mutex *lock);
@@ -156,10 +136,29 @@ extern bool __rt_mutex_futex_unlock(struct rt_mutex *lock,
extern void rt_mutex_postunlock(struct wake_q_head *wake_q);
-#ifdef CONFIG_DEBUG_RT_MUTEXES
-# include "rtmutex-debug.h"
-#else
-# include "rtmutex.h"
-#endif
+/* Debug functions */
+static inline void debug_rt_mutex_unlock(struct rt_mutex *lock)
+{
+ if (IS_ENABLED(CONFIG_DEBUG_RT_MUTEXES))
+ DEBUG_LOCKS_WARN_ON(rt_mutex_owner(lock) != current);
+}
+
+static inline void debug_rt_mutex_proxy_unlock(struct rt_mutex *lock)
+{
+ if (IS_ENABLED(CONFIG_DEBUG_RT_MUTEXES))
+ DEBUG_LOCKS_WARN_ON(!rt_mutex_owner(lock));
+}
+
+static inline void debug_rt_mutex_init_waiter(struct rt_mutex_waiter *waiter)
+{
+ if (IS_ENABLED(CONFIG_DEBUG_RT_MUTEXES))
+ memset(waiter, 0x11, sizeof(*waiter));
+}
+
+static inline void debug_rt_mutex_free_waiter(struct rt_mutex_waiter *waiter)
+{
+ if (IS_ENABLED(CONFIG_DEBUG_RT_MUTEXES))
+ memset(waiter, 0x22, sizeof(*waiter));
+}
#endif
diff --git a/kernel/locking/rwsem.c b/kernel/locking/rwsem.c
index abba5df50006..809b0016d344 100644
--- a/kernel/locking/rwsem.c
+++ b/kernel/locking/rwsem.c
@@ -632,7 +632,7 @@ static inline bool rwsem_can_spin_on_owner(struct rw_semaphore *sem)
}
/*
- * The rwsem_spin_on_owner() function returns the folowing 4 values
+ * The rwsem_spin_on_owner() function returns the following 4 values
* depending on the lock owner state.
* OWNER_NULL : owner is currently NULL
* OWNER_WRITER: when owner changes and is a writer
@@ -819,7 +819,7 @@ static bool rwsem_optimistic_spin(struct rw_semaphore *sem)
* we try to get it. The new owner may be a spinnable
* writer.
*
- * To take advantage of two scenarios listed agove, the RT
+ * To take advantage of two scenarios listed above, the RT
* task is made to retry one more time to see if it can
* acquire the lock or continue spinning on the new owning
* writer. Of course, if the time lag is long enough or the
diff --git a/kernel/locking/spinlock.c b/kernel/locking/spinlock.c
index 0ff08380f531..c8d7ad9fb9b2 100644
--- a/kernel/locking/spinlock.c
+++ b/kernel/locking/spinlock.c
@@ -58,10 +58,10 @@ EXPORT_PER_CPU_SYMBOL(__mmiowb_state);
/*
* We build the __lock_function inlines here. They are too large for
* inlining all over the place, but here is only one user per function
- * which embedds them into the calling _lock_function below.
+ * which embeds them into the calling _lock_function below.
*
* This could be a long-held lock. We both prepare to spin for a long
- * time (making _this_ CPU preemptable if possible), and we also signal
+ * time (making _this_ CPU preemptible if possible), and we also signal
* towards that other CPU that it should break the lock ASAP.
*/
#define BUILD_LOCK_OPS(op, locktype) \
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index b2890f6e6d6f..347127e73422 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -5396,25 +5396,25 @@ static void sched_dynamic_update(int mode)
switch (mode) {
case preempt_dynamic_none:
static_call_update(cond_resched, __cond_resched);
- static_call_update(might_resched, (typeof(&__cond_resched)) __static_call_return0);
- static_call_update(preempt_schedule, (typeof(&preempt_schedule)) NULL);
- static_call_update(preempt_schedule_notrace, (typeof(&preempt_schedule_notrace)) NULL);
- static_call_update(irqentry_exit_cond_resched, (typeof(&irqentry_exit_cond_resched)) NULL);
+ static_call_update(might_resched, (void *)&__static_call_return0);
+ static_call_update(preempt_schedule, NULL);
+ static_call_update(preempt_schedule_notrace, NULL);
+ static_call_update(irqentry_exit_cond_resched, NULL);
pr_info("Dynamic Preempt: none\n");
break;
case preempt_dynamic_voluntary:
static_call_update(cond_resched, __cond_resched);
static_call_update(might_resched, __cond_resched);
- static_call_update(preempt_schedule, (typeof(&preempt_schedule)) NULL);
- static_call_update(preempt_schedule_notrace, (typeof(&preempt_schedule_notrace)) NULL);
- static_call_update(irqentry_exit_cond_resched, (typeof(&irqentry_exit_cond_resched)) NULL);
+ static_call_update(preempt_schedule, NULL);
+ static_call_update(preempt_schedule_notrace, NULL);
+ static_call_update(irqentry_exit_cond_resched, NULL);
pr_info("Dynamic Preempt: voluntary\n");
break;
case preempt_dynamic_full:
- static_call_update(cond_resched, (typeof(&__cond_resched)) __static_call_return0);
- static_call_update(might_resched, (typeof(&__cond_resched)) __static_call_return0);
+ static_call_update(cond_resched, (void *)&__static_call_return0);
+ static_call_update(might_resched, (void *)&__static_call_return0);
static_call_update(preempt_schedule, __preempt_schedule_func);
static_call_update(preempt_schedule_notrace, __preempt_schedule_notrace_func);
static_call_update(irqentry_exit_cond_resched, irqentry_exit_cond_resched);
diff --git a/kernel/smp.c b/kernel/smp.c
index aeb0adfa0606..f472ef623956 100644
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -24,14 +24,70 @@
#include <linux/sched/clock.h>
#include <linux/nmi.h>
#include <linux/sched/debug.h>
+#include <linux/jump_label.h>
#include "smpboot.h"
#include "sched/smp.h"
#define CSD_TYPE(_csd) ((_csd)->node.u_flags & CSD_FLAG_TYPE_MASK)
+#ifdef CONFIG_CSD_LOCK_WAIT_DEBUG
+union cfd_seq_cnt {
+ u64 val;
+ struct {
+ u64 src:16;
+ u64 dst:16;
+#define CFD_SEQ_NOCPU 0xffff
+ u64 type:4;
+#define CFD_SEQ_QUEUE 0
+#define CFD_SEQ_IPI 1
+#define CFD_SEQ_NOIPI 2
+#define CFD_SEQ_PING 3
+#define CFD_SEQ_PINGED 4
+#define CFD_SEQ_HANDLE 5
+#define CFD_SEQ_DEQUEUE 6
+#define CFD_SEQ_IDLE 7
+#define CFD_SEQ_GOTIPI 8
+#define CFD_SEQ_HDLEND 9
+ u64 cnt:28;
+ } u;
+};
+
+static char *seq_type[] = {
+ [CFD_SEQ_QUEUE] = "queue",
+ [CFD_SEQ_IPI] = "ipi",
+ [CFD_SEQ_NOIPI] = "noipi",
+ [CFD_SEQ_PING] = "ping",
+ [CFD_SEQ_PINGED] = "pinged",
+ [CFD_SEQ_HANDLE] = "handle",
+ [CFD_SEQ_DEQUEUE] = "dequeue (src CPU 0 == empty)",
+ [CFD_SEQ_IDLE] = "idle",
+ [CFD_SEQ_GOTIPI] = "gotipi",
+ [CFD_SEQ_HDLEND] = "hdlend (src CPU 0 == early)",
+};
+
+struct cfd_seq_local {
+ u64 ping;
+ u64 pinged;
+ u64 handle;
+ u64 dequeue;
+ u64 idle;
+ u64 gotipi;
+ u64 hdlend;
+};
+#endif
+
+struct cfd_percpu {
+ call_single_data_t csd;
+#ifdef CONFIG_CSD_LOCK_WAIT_DEBUG
+ u64 seq_queue;
+ u64 seq_ipi;
+ u64 seq_noipi;
+#endif
+};
+
struct call_function_data {
- call_single_data_t __percpu *csd;
+ struct cfd_percpu __percpu *pcpu;
cpumask_var_t cpumask;
cpumask_var_t cpumask_ipi;
};
@@ -54,8 +110,8 @@ int smpcfd_prepare_cpu(unsigned int cpu)
free_cpumask_var(cfd->cpumask);
return -ENOMEM;
}
- cfd->csd = alloc_percpu(call_single_data_t);
- if (!cfd->csd) {
+ cfd->pcpu = alloc_percpu(struct cfd_percpu);
+ if (!cfd->pcpu) {
free_cpumask_var(cfd->cpumask);
free_cpumask_var(cfd->cpumask_ipi);
return -ENOMEM;
@@ -70,7 +126,7 @@ int smpcfd_dead_cpu(unsigned int cpu)
free_cpumask_var(cfd->cpumask);
free_cpumask_var(cfd->cpumask_ipi);
- free_percpu(cfd->csd);
+ free_percpu(cfd->pcpu);
return 0;
}
@@ -102,15 +158,60 @@ void __init call_function_init(void)
#ifdef CONFIG_CSD_LOCK_WAIT_DEBUG
+static DEFINE_STATIC_KEY_FALSE(csdlock_debug_enabled);
+static DEFINE_STATIC_KEY_FALSE(csdlock_debug_extended);
+
+static int __init csdlock_debug(char *str)
+{
+ unsigned int val = 0;
+
+ if (str && !strcmp(str, "ext")) {
+ val = 1;
+ static_branch_enable(&csdlock_debug_extended);
+ } else
+ get_option(&str, &val);
+
+ if (val)
+ static_branch_enable(&csdlock_debug_enabled);
+
+ return 0;
+}
+early_param("csdlock_debug", csdlock_debug);
+
static DEFINE_PER_CPU(call_single_data_t *, cur_csd);
static DEFINE_PER_CPU(smp_call_func_t, cur_csd_func);
static DEFINE_PER_CPU(void *, cur_csd_info);
+static DEFINE_PER_CPU(struct cfd_seq_local, cfd_seq_local);
#define CSD_LOCK_TIMEOUT (5ULL * NSEC_PER_SEC)
static atomic_t csd_bug_count = ATOMIC_INIT(0);
+static u64 cfd_seq;
+
+#define CFD_SEQ(s, d, t, c) \
+ (union cfd_seq_cnt){ .u.src = s, .u.dst = d, .u.type = t, .u.cnt = c }
+
+static u64 cfd_seq_inc(unsigned int src, unsigned int dst, unsigned int type)
+{
+ union cfd_seq_cnt new, old;
+
+ new = CFD_SEQ(src, dst, type, 0);
+
+ do {
+ old.val = READ_ONCE(cfd_seq);
+ new.u.cnt = old.u.cnt + 1;
+ } while (cmpxchg(&cfd_seq, old.val, new.val) != old.val);
+
+ return old.val;
+}
+
+#define cfd_seq_store(var, src, dst, type) \
+ do { \
+ if (static_branch_unlikely(&csdlock_debug_extended)) \
+ var = cfd_seq_inc(src, dst, type); \
+ } while (0)
/* Record current CSD work for current CPU, NULL to erase. */
-static void csd_lock_record(call_single_data_t *csd)
+static void __csd_lock_record(call_single_data_t *csd)
{
if (!csd) {
smp_mb(); /* NULL cur_csd after unlock. */
@@ -125,7 +226,13 @@ static void csd_lock_record(call_single_data_t *csd)
/* Or before unlock, as the case may be. */
}
-static __always_inline int csd_lock_wait_getcpu(call_single_data_t *csd)
+static __always_inline void csd_lock_record(call_single_data_t *csd)
+{
+ if (static_branch_unlikely(&csdlock_debug_enabled))
+ __csd_lock_record(csd);
+}
+
+static int csd_lock_wait_getcpu(call_single_data_t *csd)
{
unsigned int csd_type;
@@ -135,12 +242,86 @@ static __always_inline int csd_lock_wait_getcpu(call_single_data_t *csd)
return -1;
}
+static void cfd_seq_data_add(u64 val, unsigned int src, unsigned int dst,
+ unsigned int type, union cfd_seq_cnt *data,
+ unsigned int *n_data, unsigned int now)
+{
+ union cfd_seq_cnt new[2];
+ unsigned int i, j, k;
+
+ new[0].val = val;
+ new[1] = CFD_SEQ(src, dst, type, new[0].u.cnt + 1);
+
+ for (i = 0; i < 2; i++) {
+ if (new[i].u.cnt <= now)
+ new[i].u.cnt |= 0x80000000U;
+ for (j = 0; j < *n_data; j++) {
+ if (new[i].u.cnt == data[j].u.cnt) {
+ /* Direct read value trumps generated one. */
+ if (i == 0)
+ data[j].val = new[i].val;
+ break;
+ }
+ if (new[i].u.cnt < data[j].u.cnt) {
+ for (k = *n_data; k > j; k--)
+ data[k].val = data[k - 1].val;
+ data[j].val = new[i].val;
+ (*n_data)++;
+ break;
+ }
+ }
+ if (j == *n_data) {
+ data[j].val = new[i].val;
+ (*n_data)++;
+ }
+ }
+}
+
+static const char *csd_lock_get_type(unsigned int type)
+{
+ return (type >= ARRAY_SIZE(seq_type)) ? "?" : seq_type[type];
+}
+
+static void csd_lock_print_extended(call_single_data_t *csd, int cpu)
+{
+ struct cfd_seq_local *seq = &per_cpu(cfd_seq_local, cpu);
+ unsigned int srccpu = csd->node.src;
+ struct call_function_data *cfd = per_cpu_ptr(&cfd_data, srccpu);
+ struct cfd_percpu *pcpu = per_cpu_ptr(cfd->pcpu, cpu);
+ unsigned int now;
+ union cfd_seq_cnt data[2 * ARRAY_SIZE(seq_type)];
+ unsigned int n_data = 0, i;
+
+ data[0].val = READ_ONCE(cfd_seq);
+ now = data[0].u.cnt;
+
+ cfd_seq_data_add(pcpu->seq_queue, srccpu, cpu, CFD_SEQ_QUEUE, data, &n_data, now);
+ cfd_seq_data_add(pcpu->seq_ipi, srccpu, cpu, CFD_SEQ_IPI, data, &n_data, now);
+ cfd_seq_data_add(pcpu->seq_noipi, srccpu, cpu, CFD_SEQ_NOIPI, data, &n_data, now);
+
+ cfd_seq_data_add(per_cpu(cfd_seq_local.ping, srccpu), srccpu, CFD_SEQ_NOCPU, CFD_SEQ_PING, data, &n_data, now);
+ cfd_seq_data_add(per_cpu(cfd_seq_local.pinged, srccpu), srccpu, CFD_SEQ_NOCPU, CFD_SEQ_PINGED, data, &n_data, now);
+
+ cfd_seq_data_add(seq->idle, CFD_SEQ_NOCPU, cpu, CFD_SEQ_IDLE, data, &n_data, now);
+ cfd_seq_data_add(seq->gotipi, CFD_SEQ_NOCPU, cpu, CFD_SEQ_GOTIPI, data, &n_data, now);
+ cfd_seq_data_add(seq->handle, CFD_SEQ_NOCPU, cpu, CFD_SEQ_HANDLE, data, &n_data, now);
+ cfd_seq_data_add(seq->dequeue, CFD_SEQ_NOCPU, cpu, CFD_SEQ_DEQUEUE, data, &n_data, now);
+ cfd_seq_data_add(seq->hdlend, CFD_SEQ_NOCPU, cpu, CFD_SEQ_HDLEND, data, &n_data, now);
+
+ for (i = 0; i < n_data; i++) {
+ pr_alert("\tcsd: cnt(%07x): %04x->%04x %s\n",
+ data[i].u.cnt & ~0x80000000U, data[i].u.src,
+ data[i].u.dst, csd_lock_get_type(data[i].u.type));
+ }
+ pr_alert("\tcsd: cnt now: %07x\n", now);
+}
+
/*
* Complain if too much time spent waiting. Note that only
* the CSD_TYPE_SYNC/ASYNC types provide the destination CPU,
* so waiting on other types gets much less information.
*/
-static __always_inline bool csd_lock_wait_toolong(call_single_data_t *csd, u64 ts0, u64 *ts1, int *bug_id)
+static bool csd_lock_wait_toolong(call_single_data_t *csd, u64 ts0, u64 *ts1, int *bug_id)
{
int cpu = -1;
int cpux;
@@ -184,6 +365,8 @@ static __always_inline bool csd_lock_wait_toolong(call_single_data_t *csd, u64 t
*bug_id, !cpu_cur_csd ? "unresponsive" : "handling this request");
}
if (cpu >= 0) {
+ if (static_branch_unlikely(&csdlock_debug_extended))
+ csd_lock_print_extended(csd, cpu);
if (!trigger_single_cpu_backtrace(cpu))
dump_cpu_task(cpu);
if (!cpu_cur_csd) {
@@ -204,7 +387,7 @@ static __always_inline bool csd_lock_wait_toolong(call_single_data_t *csd, u64 t
* previous function call. For multi-cpu calls its even more interesting
* as we'll have to ensure no other cpu is observing our csd.
*/
-static __always_inline void csd_lock_wait(call_single_data_t *csd)
+static void __csd_lock_wait(call_single_data_t *csd)
{
int bug_id = 0;
u64 ts0, ts1;
@@ -218,7 +401,36 @@ static __always_inline void csd_lock_wait(call_single_data_t *csd)
smp_acquire__after_ctrl_dep();
}
+static __always_inline void csd_lock_wait(call_single_data_t *csd)
+{
+ if (static_branch_unlikely(&csdlock_debug_enabled)) {
+ __csd_lock_wait(csd);
+ return;
+ }
+
+ smp_cond_load_acquire(&csd->node.u_flags, !(VAL & CSD_FLAG_LOCK));
+}
+
+static void __smp_call_single_queue_debug(int cpu, struct llist_node *node)
+{
+ unsigned int this_cpu = smp_processor_id();
+ struct cfd_seq_local *seq = this_cpu_ptr(&cfd_seq_local);
+ struct call_function_data *cfd = this_cpu_ptr(&cfd_data);
+ struct cfd_percpu *pcpu = per_cpu_ptr(cfd->pcpu, cpu);
+
+ cfd_seq_store(pcpu->seq_queue, this_cpu, cpu, CFD_SEQ_QUEUE);
+ if (llist_add(node, &per_cpu(call_single_queue, cpu))) {
+ cfd_seq_store(pcpu->seq_ipi, this_cpu, cpu, CFD_SEQ_IPI);
+ cfd_seq_store(seq->ping, this_cpu, cpu, CFD_SEQ_PING);
+ send_call_function_single_ipi(cpu);
+ cfd_seq_store(seq->pinged, this_cpu, cpu, CFD_SEQ_PINGED);
+ } else {
+ cfd_seq_store(pcpu->seq_noipi, this_cpu, cpu, CFD_SEQ_NOIPI);
+ }
+}
#else
+#define cfd_seq_store(var, src, dst, type)
+
static void csd_lock_record(call_single_data_t *csd)
{
}
@@ -256,6 +468,19 @@ static DEFINE_PER_CPU_SHARED_ALIGNED(call_single_data_t, csd_data);
void __smp_call_single_queue(int cpu, struct llist_node *node)
{
+#ifdef CONFIG_CSD_LOCK_WAIT_DEBUG
+ if (static_branch_unlikely(&csdlock_debug_extended)) {
+ unsigned int type;
+
+ type = CSD_TYPE(container_of(node, call_single_data_t,
+ node.llist));
+ if (type == CSD_TYPE_SYNC || type == CSD_TYPE_ASYNC) {
+ __smp_call_single_queue_debug(cpu, node);
+ return;
+ }
+ }
+#endif
+
/*
* The list addition should be visible before sending the IPI
* handler locks the list to pull the entry off it because of
@@ -314,6 +539,8 @@ static int generic_exec_single(int cpu, call_single_data_t *csd)
*/
void generic_smp_call_function_single_interrupt(void)
{
+ cfd_seq_store(this_cpu_ptr(&cfd_seq_local)->gotipi, CFD_SEQ_NOCPU,
+ smp_processor_id(), CFD_SEQ_GOTIPI);
flush_smp_call_function_queue(true);
}
@@ -341,7 +568,13 @@ static void flush_smp_call_function_queue(bool warn_cpu_offline)
lockdep_assert_irqs_disabled();
head = this_cpu_ptr(&call_single_queue);
+ cfd_seq_store(this_cpu_ptr(&cfd_seq_local)->handle, CFD_SEQ_NOCPU,
+ smp_processor_id(), CFD_SEQ_HANDLE);
entry = llist_del_all(head);
+ cfd_seq_store(this_cpu_ptr(&cfd_seq_local)->dequeue,
+ /* Special meaning of source cpu: 0 == queue empty */
+ entry ? CFD_SEQ_NOCPU : 0,
+ smp_processor_id(), CFD_SEQ_DEQUEUE);
entry = llist_reverse_order(entry);
/* There shouldn't be any pending callbacks on an offline CPU. */
@@ -400,8 +633,12 @@ static void flush_smp_call_function_queue(bool warn_cpu_offline)
}
}
- if (!entry)
+ if (!entry) {
+ cfd_seq_store(this_cpu_ptr(&cfd_seq_local)->hdlend,
+ 0, smp_processor_id(),
+ CFD_SEQ_HDLEND);
return;
+ }
/*
* Second; run all !SYNC callbacks.
@@ -439,6 +676,9 @@ static void flush_smp_call_function_queue(bool warn_cpu_offline)
*/
if (entry)
sched_ttwu_pending(entry);
+
+ cfd_seq_store(this_cpu_ptr(&cfd_seq_local)->hdlend, CFD_SEQ_NOCPU,
+ smp_processor_id(), CFD_SEQ_HDLEND);
}
void flush_smp_call_function_from_idle(void)
@@ -448,6 +688,8 @@ void flush_smp_call_function_from_idle(void)
if (llist_empty(this_cpu_ptr(&call_single_queue)))
return;
+ cfd_seq_store(this_cpu_ptr(&cfd_seq_local)->idle, CFD_SEQ_NOCPU,
+ smp_processor_id(), CFD_SEQ_IDLE);
local_irq_save(flags);
flush_smp_call_function_queue(true);
if (local_softirq_pending())
@@ -664,7 +906,8 @@ static void smp_call_function_many_cond(const struct cpumask *mask,
cpumask_clear(cfd->cpumask_ipi);
for_each_cpu(cpu, cfd->cpumask) {
- call_single_data_t *csd = per_cpu_ptr(cfd->csd, cpu);
+ struct cfd_percpu *pcpu = per_cpu_ptr(cfd->pcpu, cpu);
+ call_single_data_t *csd = &pcpu->csd;
if (cond_func && !cond_func(cpu, info))
continue;
@@ -678,18 +921,27 @@ static void smp_call_function_many_cond(const struct cpumask *mask,
csd->node.src = smp_processor_id();
csd->node.dst = cpu;
#endif
- if (llist_add(&csd->node.llist, &per_cpu(call_single_queue, cpu)))
+ cfd_seq_store(pcpu->seq_queue, this_cpu, cpu, CFD_SEQ_QUEUE);
+ if (llist_add(&csd->node.llist, &per_cpu(call_single_queue, cpu))) {
__cpumask_set_cpu(cpu, cfd->cpumask_ipi);
+ cfd_seq_store(pcpu->seq_ipi, this_cpu, cpu, CFD_SEQ_IPI);
+ } else {
+ cfd_seq_store(pcpu->seq_noipi, this_cpu, cpu, CFD_SEQ_NOIPI);
+ }
}
/* Send a message to all CPUs in the map */
+ cfd_seq_store(this_cpu_ptr(&cfd_seq_local)->ping, this_cpu,
+ CFD_SEQ_NOCPU, CFD_SEQ_PING);
arch_send_call_function_ipi_mask(cfd->cpumask_ipi);
+ cfd_seq_store(this_cpu_ptr(&cfd_seq_local)->pinged, this_cpu,
+ CFD_SEQ_NOCPU, CFD_SEQ_PINGED);
if (wait) {
for_each_cpu(cpu, cfd->cpumask) {
call_single_data_t *csd;
- csd = per_cpu_ptr(cfd->csd, cpu);
+ csd = &per_cpu_ptr(cfd->pcpu, cpu)->csd;
csd_lock_wait(csd);
}
}
diff --git a/kernel/static_call.c b/kernel/static_call.c
index 2c5950b0b90e..723fcc9d20db 100644
--- a/kernel/static_call.c
+++ b/kernel/static_call.c
@@ -165,13 +165,13 @@ void __static_call_update(struct static_call_key *key, void *tramp, void *func)
stop = __stop_static_call_sites;
-#ifdef CONFIG_MODULES
if (mod) {
+#ifdef CONFIG_MODULES
stop = mod->static_call_sites +
mod->num_static_call_sites;
init = mod->state == MODULE_STATE_COMING;
- }
#endif
+ }
for (site = site_mod->sites;
site < stop && static_call_key(site) == key; site++) {
diff --git a/lib/Kconfig.kcsan b/lib/Kconfig.kcsan
index f271ff5fbb5a..0440f373248e 100644
--- a/lib/Kconfig.kcsan
+++ b/lib/Kconfig.kcsan
@@ -69,8 +69,9 @@ config KCSAN_SELFTEST
panic. Recommended to be enabled, ensuring critical functionality
works as intended.
-config KCSAN_TEST
- tristate "KCSAN test for integrated runtime behaviour"
+config KCSAN_KUNIT_TEST
+ tristate "KCSAN test for integrated runtime behaviour" if !KUNIT_ALL_TESTS
+ default KUNIT_ALL_TESTS
depends on TRACEPOINTS && KUNIT
select TORTURE_TEST
help
diff --git a/tools/memory-model/Documentation/access-marking.txt b/tools/memory-model/Documentation/access-marking.txt
new file mode 100644
index 000000000000..1ab189f51f55
--- /dev/null
+++ b/tools/memory-model/Documentation/access-marking.txt
@@ -0,0 +1,479 @@
+MARKING SHARED-MEMORY ACCESSES
+==============================
+
+This document provides guidelines for marking intentionally concurrent
+normal accesses to shared memory, that is "normal" as in accesses that do
+not use read-modify-write atomic operations. It also describes how to
+document these accesses, both with comments and with special assertions
+processed by the Kernel Concurrency Sanitizer (KCSAN). This discussion
+builds on an earlier LWN article [1].
+
+
+ACCESS-MARKING OPTIONS
+======================
+
+The Linux kernel provides the following access-marking options:
+
+1. Plain C-language accesses (unmarked), for example, "a = b;"
+
+2. Data-race marking, for example, "data_race(a = b);"
+
+3. READ_ONCE(), for example, "a = READ_ONCE(b);"
+ The various forms of atomic_read() also fit in here.
+
+4. WRITE_ONCE(), for example, "WRITE_ONCE(a, b);"
+ The various forms of atomic_set() also fit in here.
+
+
+These may be used in combination, as shown in this admittedly improbable
+example:
+
+ WRITE_ONCE(a, b + data_race(c + d) + READ_ONCE(e));
+
+Neither plain C-language accesses nor data_race() (#1 and #2 above) place
+any sort of constraint on the compiler's choice of optimizations [2].
+In contrast, READ_ONCE() and WRITE_ONCE() (#3 and #4 above) restrict the
+compiler's use of code-motion and common-subexpression optimizations.
+Therefore, if a given access is involved in an intentional data race,
+using READ_ONCE() for loads and WRITE_ONCE() for stores is usually
+preferable to data_race(), which in turn is usually preferable to plain
+C-language accesses.
+
+KCSAN will complain about many types of data races involving plain
+C-language accesses, but marking all accesses involved in a given data
+race with one of data_race(), READ_ONCE(), or WRITE_ONCE(), will prevent
+KCSAN from complaining. Of course, lack of KCSAN complaints does not
+imply correct code. Therefore, please take a thoughtful approach
+when responding to KCSAN complaints. Churning the code base with
+ill-considered additions of data_race(), READ_ONCE(), and WRITE_ONCE()
+is unhelpful.
+
+In fact, the following sections describe situations where use of
+data_race() and even plain C-language accesses is preferable to
+READ_ONCE() and WRITE_ONCE().
+
+
+Use of the data_race() Macro
+----------------------------
+
+Here are some situations where data_race() should be used instead of
+READ_ONCE() and WRITE_ONCE():
+
+1. Data-racy loads from shared variables whose values are used only
+ for diagnostic purposes.
+
+2. Data-racy reads whose values are checked against marked reload.
+
+3. Reads whose values feed into error-tolerant heuristics.
+
+4. Writes setting values that feed into error-tolerant heuristics.
+
+
+Data-Racy Reads for Approximate Diagnostics
+
+Approximate diagnostics include lockdep reports, monitoring/statistics
+(including /proc and /sys output), WARN*()/BUG*() checks whose return
+values are ignored, and other situations where reads from shared variables
+are not an integral part of the core concurrency design.
+
+In fact, use of data_race() instead READ_ONCE() for these diagnostic
+reads can enable better checking of the remaining accesses implementing
+the core concurrency design. For example, suppose that the core design
+prevents any non-diagnostic reads from shared variable x from running
+concurrently with updates to x. Then using plain C-language writes
+to x allows KCSAN to detect reads from x from within regions of code
+that fail to exclude the updates. In this case, it is important to use
+data_race() for the diagnostic reads because otherwise KCSAN would give
+false-positive warnings about these diagnostic reads.
+
+In theory, plain C-language loads can also be used for this use case.
+However, in practice this will have the disadvantage of causing KCSAN
+to generate false positives because KCSAN will have no way of knowing
+that the resulting data race was intentional.
+
+
+Data-Racy Reads That Are Checked Against Marked Reload
+
+The values from some reads are not implicitly trusted. They are instead
+fed into some operation that checks the full value against a later marked
+load from memory, which means that the occasional arbitrarily bogus value
+is not a problem. For example, if a bogus value is fed into cmpxchg(),
+all that happens is that this cmpxchg() fails, which normally results
+in a retry. Unless the race condition that resulted in the bogus value
+recurs, this retry will with high probability succeed, so no harm done.
+
+However, please keep in mind that a data_race() load feeding into
+a cmpxchg_relaxed() might still be subject to load fusing on some
+architectures. Therefore, it is best to capture the return value from
+the failing cmpxchg() for the next iteration of the loop, an approach
+that provides the compiler much less scope for mischievous optimizations.
+Capturing the return value from cmpxchg() also saves a memory reference
+in many cases.
+
+In theory, plain C-language loads can also be used for this use case.
+However, in practice this will have the disadvantage of causing KCSAN
+to generate false positives because KCSAN will have no way of knowing
+that the resulting data race was intentional.
+
+
+Reads Feeding Into Error-Tolerant Heuristics
+
+Values from some reads feed into heuristics that can tolerate occasional
+errors. Such reads can use data_race(), thus allowing KCSAN to focus on
+the other accesses to the relevant shared variables. But please note
+that data_race() loads are subject to load fusing, which can result in
+consistent errors, which in turn are quite capable of breaking heuristics.
+Therefore use of data_race() should be limited to cases where some other
+code (such as a barrier() call) will force the occasional reload.
+
+In theory, plain C-language loads can also be used for this use case.
+However, in practice this will have the disadvantage of causing KCSAN
+to generate false positives because KCSAN will have no way of knowing
+that the resulting data race was intentional.
+
+
+Writes Setting Values Feeding Into Error-Tolerant Heuristics
+
+The values read into error-tolerant heuristics come from somewhere,
+for example, from sysfs. This means that some code in sysfs writes
+to this same variable, and these writes can also use data_race().
+After all, if the heuristic can tolerate the occasional bogus value
+due to compiler-mangled reads, it can also tolerate the occasional
+compiler-mangled write, at least assuming that the proper value is in
+place once the write completes.
+
+Plain C-language stores can also be used for this use case. However,
+in kernels built with CONFIG_KCSAN_ASSUME_PLAIN_WRITES_ATOMIC=n, this
+will have the disadvantage of causing KCSAN to generate false positives
+because KCSAN will have no way of knowing that the resulting data race
+was intentional.
+
+
+Use of Plain C-Language Accesses
+--------------------------------
+
+Here are some example situations where plain C-language accesses should
+used instead of READ_ONCE(), WRITE_ONCE(), and data_race():
+
+1. Accesses protected by mutual exclusion, including strict locking
+ and sequence locking.
+
+2. Initialization-time and cleanup-time accesses. This covers a
+ wide variety of situations, including the uniprocessor phase of
+ system boot, variables to be used by not-yet-spawned kthreads,
+ structures not yet published to reference-counted or RCU-protected
+ data structures, and the cleanup side of any of these situations.
+
+3. Per-CPU variables that are not accessed from other CPUs.
+
+4. Private per-task variables, including on-stack variables, some
+ fields in the task_struct structure, and task-private heap data.
+
+5. Any other loads for which there is not supposed to be a concurrent
+ store to that same variable.
+
+6. Any other stores for which there should be neither concurrent
+ loads nor concurrent stores to that same variable.
+
+ But note that KCSAN makes two explicit exceptions to this rule
+ by default, refraining from flagging plain C-language stores:
+
+ a. No matter what. You can override this default by building
+ with CONFIG_KCSAN_ASSUME_PLAIN_WRITES_ATOMIC=n.
+
+ b. When the store writes the value already contained in
+ that variable. You can override this default by building
+ with CONFIG_KCSAN_REPORT_VALUE_CHANGE_ONLY=n.
+
+ c. When one of the stores is in an interrupt handler and
+ the other in the interrupted code. You can override this
+ default by building with CONFIG_KCSAN_INTERRUPT_WATCHER=y.
+
+Note that it is important to use plain C-language accesses in these cases,
+because doing otherwise prevents KCSAN from detecting violations of your
+code's synchronization rules.
+
+
+ACCESS-DOCUMENTATION OPTIONS
+============================
+
+It is important to comment marked accesses so that people reading your
+code, yourself included, are reminded of the synchronization design.
+However, it is even more important to comment plain C-language accesses
+that are intentionally involved in data races. Such comments are
+needed to remind people reading your code, again, yourself included,
+of how the compiler has been prevented from optimizing those accesses
+into concurrency bugs.
+
+It is also possible to tell KCSAN about your synchronization design.
+For example, ASSERT_EXCLUSIVE_ACCESS(foo) tells KCSAN that any
+concurrent access to variable foo by any other CPU is an error, even
+if that concurrent access is marked with READ_ONCE(). In addition,
+ASSERT_EXCLUSIVE_WRITER(foo) tells KCSAN that although it is OK for there
+to be concurrent reads from foo from other CPUs, it is an error for some
+other CPU to be concurrently writing to foo, even if that concurrent
+write is marked with data_race() or WRITE_ONCE().
+
+Note that although KCSAN will call out data races involving either
+ASSERT_EXCLUSIVE_ACCESS() or ASSERT_EXCLUSIVE_WRITER() on the one hand
+and data_race() writes on the other, KCSAN will not report the location
+of these data_race() writes.
+
+
+EXAMPLES
+========
+
+As noted earlier, the goal is to prevent the compiler from destroying
+your concurrent algorithm, to help the human reader, and to inform
+KCSAN of aspects of your concurrency design. This section looks at a
+few examples showing how this can be done.
+
+
+Lock Protection With Lockless Diagnostic Access
+-----------------------------------------------
+
+For example, suppose a shared variable "foo" is read only while a
+reader-writer spinlock is read-held, written only while that same
+spinlock is write-held, except that it is also read locklessly for
+diagnostic purposes. The code might look as follows:
+
+ int foo;
+ DEFINE_RWLOCK(foo_rwlock);
+
+ void update_foo(int newval)
+ {
+ write_lock(&foo_rwlock);
+ foo = newval;
+ do_something(newval);
+ write_unlock(&foo_rwlock);
+ }
+
+ int read_foo(void)
+ {
+ int ret;
+
+ read_lock(&foo_rwlock);
+ do_something_else();
+ ret = foo;
+ read_unlock(&foo_rwlock);
+ return ret;
+ }
+
+ int read_foo_diagnostic(void)
+ {
+ return data_race(foo);
+ }
+
+The reader-writer lock prevents the compiler from introducing concurrency
+bugs into any part of the main algorithm using foo, which means that
+the accesses to foo within both update_foo() and read_foo() can (and
+should) be plain C-language accesses. One benefit of making them be
+plain C-language accesses is that KCSAN can detect any erroneous lockless
+reads from or updates to foo. The data_race() in read_foo_diagnostic()
+tells KCSAN that data races are expected, and should be silently
+ignored. This data_race() also tells the human reading the code that
+read_foo_diagnostic() might sometimes return a bogus value.
+
+However, please note that your kernel must be built with
+CONFIG_KCSAN_ASSUME_PLAIN_WRITES_ATOMIC=n in order for KCSAN to
+detect a buggy lockless write. If you need KCSAN to detect such a
+write even if that write did not change the value of foo, you also
+need CONFIG_KCSAN_REPORT_VALUE_CHANGE_ONLY=n. If you need KCSAN to
+detect such a write happening in an interrupt handler running on the
+same CPU doing the legitimate lock-protected write, you also need
+CONFIG_KCSAN_INTERRUPT_WATCHER=y. With some or all of these Kconfig
+options set properly, KCSAN can be quite helpful, although it is not
+necessarily a full replacement for hardware watchpoints. On the other
+hand, neither are hardware watchpoints a full replacement for KCSAN
+because it is not always easy to tell hardware watchpoint to conditionally
+trap on accesses.
+
+
+Lock-Protected Writes With Lockless Reads
+-----------------------------------------
+
+For another example, suppose a shared variable "foo" is updated only
+while holding a spinlock, but is read locklessly. The code might look
+as follows:
+
+ int foo;
+ DEFINE_SPINLOCK(foo_lock);
+
+ void update_foo(int newval)
+ {
+ spin_lock(&foo_lock);
+ WRITE_ONCE(foo, newval);
+ ASSERT_EXCLUSIVE_WRITER(foo);
+ do_something(newval);
+ spin_unlock(&foo_wlock);
+ }
+
+ int read_foo(void)
+ {
+ do_something_else();
+ return READ_ONCE(foo);
+ }
+
+Because foo is read locklessly, all accesses are marked. The purpose
+of the ASSERT_EXCLUSIVE_WRITER() is to allow KCSAN to check for a buggy
+concurrent lockless write.
+
+
+Lockless Reads and Writes
+-------------------------
+
+For another example, suppose a shared variable "foo" is both read and
+updated locklessly. The code might look as follows:
+
+ int foo;
+
+ int update_foo(int newval)
+ {
+ int ret;
+
+ ret = xchg(&foo, newval);
+ do_something(newval);
+ return ret;
+ }
+
+ int read_foo(void)
+ {
+ do_something_else();
+ return READ_ONCE(foo);
+ }
+
+Because foo is accessed locklessly, all accesses are marked. It does
+not make sense to use ASSERT_EXCLUSIVE_WRITER() in this case because
+there really can be concurrent lockless writers. KCSAN would
+flag any concurrent plain C-language reads from foo, and given
+CONFIG_KCSAN_ASSUME_PLAIN_WRITES_ATOMIC=n, also any concurrent plain
+C-language writes to foo.
+
+
+Lockless Reads and Writes, But With Single-Threaded Initialization
+------------------------------------------------------------------
+
+For yet another example, suppose that foo is initialized in a
+single-threaded manner, but that a number of kthreads are then created
+that locklessly and concurrently access foo. Some snippets of this code
+might look as follows:
+
+ int foo;
+
+ void initialize_foo(int initval, int nkthreads)
+ {
+ int i;
+
+ foo = initval;
+ ASSERT_EXCLUSIVE_ACCESS(foo);
+ for (i = 0; i < nkthreads; i++)
+ kthread_run(access_foo_concurrently, ...);
+ }
+
+ /* Called from access_foo_concurrently(). */
+ int update_foo(int newval)
+ {
+ int ret;
+
+ ret = xchg(&foo, newval);
+ do_something(newval);
+ return ret;
+ }
+
+ /* Also called from access_foo_concurrently(). */
+ int read_foo(void)
+ {
+ do_something_else();
+ return READ_ONCE(foo);
+ }
+
+The initialize_foo() uses a plain C-language write to foo because there
+are not supposed to be concurrent accesses during initialization. The
+ASSERT_EXCLUSIVE_ACCESS() allows KCSAN to flag buggy concurrent unmarked
+reads, and the ASSERT_EXCLUSIVE_ACCESS() call further allows KCSAN to
+flag buggy concurrent writes, even if: (1) Those writes are marked or
+(2) The kernel was built with CONFIG_KCSAN_ASSUME_PLAIN_WRITES_ATOMIC=y.
+
+
+Checking Stress-Test Race Coverage
+----------------------------------
+
+When designing stress tests it is important to ensure that race conditions
+of interest really do occur. For example, consider the following code
+fragment:
+
+ int foo;
+
+ int update_foo(int newval)
+ {
+ return xchg(&foo, newval);
+ }
+
+ int xor_shift_foo(int shift, int mask)
+ {
+ int old, new, newold;
+
+ newold = data_race(foo); /* Checked by cmpxchg(). */
+ do {
+ old = newold;
+ new = (old << shift) ^ mask;
+ newold = cmpxchg(&foo, old, new);
+ } while (newold != old);
+ return old;
+ }
+
+ int read_foo(void)
+ {
+ return READ_ONCE(foo);
+ }
+
+If it is possible for update_foo(), xor_shift_foo(), and read_foo() to be
+invoked concurrently, the stress test should force this concurrency to
+actually happen. KCSAN can evaluate the stress test when the above code
+is modified to read as follows:
+
+ int foo;
+
+ int update_foo(int newval)
+ {
+ ASSERT_EXCLUSIVE_ACCESS(foo);
+ return xchg(&foo, newval);
+ }
+
+ int xor_shift_foo(int shift, int mask)
+ {
+ int old, new, newold;
+
+ newold = data_race(foo); /* Checked by cmpxchg(). */
+ do {
+ old = newold;
+ new = (old << shift) ^ mask;
+ ASSERT_EXCLUSIVE_ACCESS(foo);
+ newold = cmpxchg(&foo, old, new);
+ } while (newold != old);
+ return old;
+ }
+
+
+ int read_foo(void)
+ {
+ ASSERT_EXCLUSIVE_ACCESS(foo);
+ return READ_ONCE(foo);
+ }
+
+If a given stress-test run does not result in KCSAN complaints from
+each possible pair of ASSERT_EXCLUSIVE_ACCESS() invocations, the
+stress test needs improvement. If the stress test was to be evaluated
+on a regular basis, it would be wise to place the above instances of
+ASSERT_EXCLUSIVE_ACCESS() under #ifdef so that they did not result in
+false positives when not evaluating the stress test.
+
+
+REFERENCES
+==========
+
+[1] "Concurrency bugs should fear the big bad data-race detector (part 2)"
+ https://lwn.net/Articles/816854/
+
+[2] "Who's afraid of a big bad optimizing compiler?"
+ https://lwn.net/Articles/793253/
diff --git a/tools/memory-model/Documentation/simple.txt b/tools/memory-model/Documentation/simple.txt
index 81e1a0ec5342..4c789ec8334f 100644
--- a/tools/memory-model/Documentation/simple.txt
+++ b/tools/memory-model/Documentation/simple.txt
@@ -189,7 +189,6 @@ Additional information may be found in these files:
Documentation/atomic_t.txt
Documentation/atomic_bitops.txt
-Documentation/core-api/atomic_ops.rst
Documentation/core-api/refcount-vs-atomic.rst
Reading code using these primitives is often also quite helpful.