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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/
This commit is contained in:
Shuah Khan 2021-02-26 17:06:58 -07:00 committed by Ingo Molnar
parent 864b435514
commit 3e31f94752
2 changed files with 13 additions and 4 deletions
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11
include/linux/lockdep.h
View File

@ -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)

6
kernel/locking/lockdep.c
View File

@ -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);