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authorShuah Khan <skhan@linuxfoundation.org>2021-02-27 03:06:58 +0300
committerIngo Molnar <mingo@kernel.org>2021-03-06 14:51:05 +0300
commit3e31f94752e454bdd0ca4a1d046ee21f80c166c5 (patch)
treefb22b7e8bbf18565fe2557937ae68410458a7297
parent864b435514b286c0be2a38a02f487aa28d990ef8 (diff)
downloadlinux-3e31f94752e454bdd0ca4a1d046ee21f80c166c5.tar.xz
lockdep: Add lockdep_assert_not_held()
Some kernel functions must be called without holding a specific lock. Add lockdep_assert_not_held() to be used in these functions to detect incorrect calls while holding a lock. lockdep_assert_not_held() provides the opposite functionality of lockdep_assert_held() which is used to assert calls that require holding a specific lock. Incorporates suggestions from Peter Zijlstra to avoid misfires when lockdep_off() is employed. The need for lockdep_assert_not_held() came up in a discussion on ath10k patch. ath10k_drain_tx() and i915_vma_pin_ww() are examples of functions that can use lockdep_assert_not_held(). Signed-off-by: Shuah Khan <skhan@linuxfoundation.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/linux-wireless/871rdmu9z9.fsf@codeaurora.org/
-rw-r--r--include/linux/lockdep.h11
-rw-r--r--kernel/locking/lockdep.c6
2 files changed, 13 insertions, 4 deletions
diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h
index 7b7ebf2e28ec..dbd9ea846b36 100644
--- a/include/linux/lockdep.h
+++ b/include/linux/lockdep.h
@@ -301,8 +301,12 @@ 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) == 0); \
+ } while (0)
+
+#define lockdep_assert_not_held(l) do { \
+ WARN_ON(debug_locks && lockdep_is_held(l) == 1); \
} while (0)
#define lockdep_assert_held_write(l) do { \
@@ -393,7 +397,8 @@ 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)
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index c6d0c1dc6253..969736b33185 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -5539,8 +5539,12 @@ noinstr int lock_is_held_type(const struct lockdep_map *lock, int read)
unsigned long flags;
int ret = 0;
+ /*
+ * Avoid false negative lockdep_assert_held() and
+ * lockdep_assert_not_held().
+ */
if (unlikely(!lockdep_enabled()))
- return 1; /* avoid false negative lockdep_assert_held() */
+ return -1;
raw_local_irq_save(flags);
check_flags(flags);