From ccfbb5bed407053b27492a9adc06064d949a9aa6 Mon Sep 17 00:00:00 2001 From: Anna-Maria Gleixner Date: Tue, 12 Jun 2018 18:16:20 +0200 Subject: atomic: Add irqsave variant of atomic_dec_and_lock() There are in-tree users of atomic_dec_and_lock() which must acquire the spin lock with interrupts disabled. To workaround the lack of an irqsave variant of atomic_dec_and_lock() they use local_irq_save() at the call site. This causes extra code and creates in some places unneeded long interrupt disabled times. These places need also extra treatment for PREEMPT_RT due to the disconnect of the irq disabling and the lock function. Implement the missing irqsave variant of the function. Signed-off-by: Anna-Maria Gleixner Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Thomas Gleixner Acked-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r20180612161621.22645-3-bigeasy@linutronix.de --- include/linux/spinlock.h | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'include') diff --git a/include/linux/spinlock.h b/include/linux/spinlock.h index 1e8a46435838..fd57888d4942 100644 --- a/include/linux/spinlock.h +++ b/include/linux/spinlock.h @@ -427,6 +427,11 @@ extern int _atomic_dec_and_lock(atomic_t *atomic, spinlock_t *lock); #define atomic_dec_and_lock(atomic, lock) \ __cond_lock(lock, _atomic_dec_and_lock(atomic, lock)) +extern int _atomic_dec_and_lock_irqsave(atomic_t *atomic, spinlock_t *lock, + unsigned long *flags); +#define atomic_dec_and_lock_irqsave(atomic, lock, flags) \ + __cond_lock(lock, _atomic_dec_and_lock_irqsave(atomic, lock, &(flags))) + int alloc_bucket_spinlocks(spinlock_t **locks, unsigned int *lock_mask, size_t max_size, unsigned int cpu_mult, gfp_t gfp); -- cgit v1.2.3 From 7ea959c45769612aa92557fb6464679f5fec7d9e Mon Sep 17 00:00:00 2001 From: Anna-Maria Gleixner Date: Tue, 12 Jun 2018 18:16:21 +0200 Subject: locking/refcounts: Implement refcount_dec_and_lock_irqsave() There are in-tree users of refcount_dec_and_lock() which must acquire the spin lock with interrupts disabled. To workaround the lack of an irqsave variant of refcount_dec_and_lock() they use local_irq_save() at the call site. This causes extra code and creates in some places unneeded long interrupt disabled times. These places need also extra treatment for PREEMPT_RT due to the disconnect of the irq disabling and the lock function. Implement the missing irqsave variant of the function. Signed-off-by: Anna-Maria Gleixner Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Thomas Gleixner Acked-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r20180612161621.22645-4-bigeasy@linutronix.de [bigeasy: s@atomic_dec_and_lock@refcount_dec_and_lock@g] --- include/linux/refcount.h | 4 +++- lib/refcount.c | 28 ++++++++++++++++++++++++++++ 2 files changed, 31 insertions(+), 1 deletion(-) (limited to 'include') diff --git a/include/linux/refcount.h b/include/linux/refcount.h index 4193c41e383a..a685da2c4522 100644 --- a/include/linux/refcount.h +++ b/include/linux/refcount.h @@ -98,5 +98,7 @@ extern __must_check bool refcount_dec_if_one(refcount_t *r); extern __must_check bool refcount_dec_not_one(refcount_t *r); extern __must_check bool refcount_dec_and_mutex_lock(refcount_t *r, struct mutex *lock); extern __must_check bool refcount_dec_and_lock(refcount_t *r, spinlock_t *lock); - +extern __must_check bool refcount_dec_and_lock_irqsave(refcount_t *r, + spinlock_t *lock, + unsigned long *flags); #endif /* _LINUX_REFCOUNT_H */ diff --git a/lib/refcount.c b/lib/refcount.c index 0eb48353abe3..d3b81cefce91 100644 --- a/lib/refcount.c +++ b/lib/refcount.c @@ -350,3 +350,31 @@ bool refcount_dec_and_lock(refcount_t *r, spinlock_t *lock) } EXPORT_SYMBOL(refcount_dec_and_lock); +/** + * refcount_dec_and_lock_irqsave - return holding spinlock with disabled + * interrupts if able to decrement refcount to 0 + * @r: the refcount + * @lock: the spinlock to be locked + * @flags: saved IRQ-flags if the is acquired + * + * Same as refcount_dec_and_lock() above except that the spinlock is acquired + * with disabled interupts. + * + * Return: true and hold spinlock if able to decrement refcount to 0, false + * otherwise + */ +bool refcount_dec_and_lock_irqsave(refcount_t *r, spinlock_t *lock, + unsigned long *flags) +{ + if (refcount_dec_not_one(r)) + return false; + + spin_lock_irqsave(lock, *flags); + if (!refcount_dec_and_test(r)) { + spin_unlock_irqrestore(lock, *flags); + return false; + } + + return true; +} +EXPORT_SYMBOL(refcount_dec_and_lock_irqsave); -- cgit v1.2.3 From 6cc65be4f6f2a7186af8f3e09900787c7912dad2 Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (VMware)" Date: Thu, 21 Jun 2018 20:35:26 -0400 Subject: locking/qspinlock: Fix build for anonymous union in older GCC compilers One of my tests compiles the kernel with gcc 4.5.3, and I hit the following build error: include/linux/semaphore.h: In function 'sema_init': include/linux/semaphore.h:35:17: error: unknown field 'val' specified in initializer include/linux/semaphore.h:35:17: warning: missing braces around initializer include/linux/semaphore.h:35:17: warning: (near initialization for '(anonymous).raw_lock..val') I bisected it down to: 625e88be1f41 ("locking/qspinlock: Merge 'struct __qspinlock' into 'struct qspinlock'") ... which makes qspinlock have an anonymous union, which makes initializing it special for older compilers. By adding strategic brackets, it makes the build happy again. Signed-off-by: Steven Rostedt (VMware) Acked-by: Waiman Long Cc: Andrew Morton Cc: Boqun Feng Cc: Linus Torvalds Cc: Peter Zijlstra (Intel) Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Will Deacon Cc: linux-arm-kernel@lists.infradead.org Fixes: 625e88be1f41 ("locking/qspinlock: Merge 'struct __qspinlock' into 'struct qspinlock'") Link: http://lkml.kernel.org/r/20180621203526.172ab5c4@vmware.local.home Signed-off-by: Ingo Molnar --- include/asm-generic/qspinlock_types.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include') diff --git a/include/asm-generic/qspinlock_types.h b/include/asm-generic/qspinlock_types.h index 0763f065b975..d10f1e7d6ba8 100644 --- a/include/asm-generic/qspinlock_types.h +++ b/include/asm-generic/qspinlock_types.h @@ -63,7 +63,7 @@ typedef struct qspinlock { /* * Initializier */ -#define __ARCH_SPIN_LOCK_UNLOCKED { .val = ATOMIC_INIT(0) } +#define __ARCH_SPIN_LOCK_UNLOCKED { { .val = ATOMIC_INIT(0) } } /* * Bitfields in the atomic value: -- cgit v1.2.3