diff options
| author | Boqun Feng <boqun.feng@gmail.com> | 2023-01-12 22:59:53 -0800 |
|---|---|---|
| committer | Boqun Feng <boqun.feng@gmail.com> | 2023-03-27 11:15:23 -0700 |
| commit | 2f1f043e7bea3fbf4c1869df2f7a0312bc8ca2bf (patch) | |
| tree | 0ab78d4602459d5e358e938d31e6271df2a34519 /include/linux/lockdep.h | |
| parent | fe15c26ee26efa11741a7b632e9f23b01aca4cc6 (diff) | |
locking/lockdep: Introduce lock_sync()
Currently, functions like synchronize_srcu() do not have lockdep
annotations resembling those of other write-side locking primitives.
Such annotations might look as follows:
lock_acquire();
lock_release();
Such annotations would tell lockdep that synchronize_srcu() acts like
an empty critical section that waits for other (read-side) critical
sections to finish. This would definitely catch some deadlock, but
as pointed out by Paul Mckenney [1], this could also introduce false
positives because of irq-safe/unsafe detection. Of course, there are
tricks could help with this:
might_sleep(); // Existing statement in __synchronize_srcu().
if (IS_ENABLED(CONFIG_PROVE_LOCKING)) {
local_irq_disable();
lock_acquire();
lock_release();
local_irq_enable();
}
But it would be better for lockdep to provide a separate annonation for
functions like synchronize_srcu(), so that people won't need to repeat
the ugly tricks above.
Therefore introduce lock_sync(), which is simply an lock+unlock
pair with no irq safe/unsafe deadlock check. This works because the
to-be-annontated functions do not create real critical sections, and
there is therefore no way that irq can create extra dependencies.
[1]: https://lore.kernel.org/lkml/20180412021233.ewncg5jjuzjw3x62@tardis/
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Acked-by: Waiman Long <longman@redhat.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
[ boqun: Fix typos reported by Davidlohr Bueso and Paul E. Mckenney ]
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Diffstat (limited to 'include/linux/lockdep.h')
| -rw-r--r-- | include/linux/lockdep.h | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h index 1023f349af71..14d9dbedc6c1 100644 --- a/include/linux/lockdep.h +++ b/include/linux/lockdep.h @@ -268,6 +268,10 @@ extern void lock_acquire(struct lockdep_map *lock, unsigned int subclass, extern void lock_release(struct lockdep_map *lock, unsigned long ip); +extern void lock_sync(struct lockdep_map *lock, unsigned int subclass, + int read, int check, struct lockdep_map *nest_lock, + unsigned long ip); + /* lock_is_held_type() returns */ #define LOCK_STATE_UNKNOWN -1 #define LOCK_STATE_NOT_HELD 0 @@ -554,6 +558,7 @@ do { \ #define lock_map_acquire_read(l) lock_acquire_shared_recursive(l, 0, 0, NULL, _THIS_IP_) #define lock_map_acquire_tryread(l) lock_acquire_shared_recursive(l, 0, 1, NULL, _THIS_IP_) #define lock_map_release(l) lock_release(l, _THIS_IP_) +#define lock_map_sync(l) lock_sync(l, 0, 0, 1, NULL, _THIS_IP_) #ifdef CONFIG_PROVE_LOCKING # define might_lock(lock) \ |