The following commit has been merged into the locking/core branch of tip: Commit-ID: ac1cce36595238680c32c3f197e5aa18db6fa7a3 Gitweb: https://git.kernel.org/tip/ac1cce36595238680c32c3f197e5aa18db6fa7a3 Author: Shuah Khan <skhan@xxxxxxxxxxxxxxxxxxx> AuthorDate: Fri, 26 Feb 2021 17:06:58 -07:00 Committer: Peter Zijlstra <peterz@xxxxxxxxxxxxx> CommitterDate: Tue, 02 Mar 2021 15:06:34 +01:00 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@xxxxxxxxxxxxxxxxxxx> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> Link: https://lore.kernel.org/linux-wireless/871rdmu9z9.fsf@xxxxxxxxxxxxxx/ --- include/linux/lockdep.h | 11 ++++++++--- kernel/locking/lockdep.c | 6 +++++- 2 files changed, 13 insertions(+), 4 deletions(-) diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h index 7b7ebf2..dbd9ea8 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 c6d0c1d..969736b 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);
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