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| author | Marco Elver <elver@google.com> | 2022-08-29 14:47:15 +0200 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2022-08-30 10:56:23 +0200 |
| commit | 01fe8a3f818e1074a9a95d624be4549ee7ea2b2b (patch) | |
| tree | 1990719e80d616d0b780490ea75e5c091292dcf3 | |
| parent | f95e5a3d59011eec1257d0e76de1e1f8969d426f (diff) | |
| download | lwn-01fe8a3f818e1074a9a95d624be4549ee7ea2b2b.tar.gz lwn-01fe8a3f818e1074a9a95d624be4549ee7ea2b2b.zip | |
locking/percpu-rwsem: Add percpu_is_write_locked() and percpu_is_read_locked()
Implement simple accessors to probe percpu-rwsem's locked state:
percpu_is_write_locked(), percpu_is_read_locked().
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Acked-by: Ian Rogers <irogers@google.com>
Link: https://lore.kernel.org/r/20220829124719.675715-11-elver@google.com
| -rw-r--r-- | include/linux/percpu-rwsem.h | 6 | ||||
| -rw-r--r-- | kernel/locking/percpu-rwsem.c | 6 |
2 files changed, 12 insertions, 0 deletions
diff --git a/include/linux/percpu-rwsem.h b/include/linux/percpu-rwsem.h index 5fda40f97fe9..36b942b67b7d 100644 --- a/include/linux/percpu-rwsem.h +++ b/include/linux/percpu-rwsem.h @@ -121,9 +121,15 @@ static inline void percpu_up_read(struct percpu_rw_semaphore *sem) preempt_enable(); } +extern bool percpu_is_read_locked(struct percpu_rw_semaphore *); extern void percpu_down_write(struct percpu_rw_semaphore *); extern void percpu_up_write(struct percpu_rw_semaphore *); +static inline bool percpu_is_write_locked(struct percpu_rw_semaphore *sem) +{ + return atomic_read(&sem->block); +} + extern int __percpu_init_rwsem(struct percpu_rw_semaphore *, const char *, struct lock_class_key *); diff --git a/kernel/locking/percpu-rwsem.c b/kernel/locking/percpu-rwsem.c index 5fe4c5495ba3..185bd1c906b0 100644 --- a/kernel/locking/percpu-rwsem.c +++ b/kernel/locking/percpu-rwsem.c @@ -192,6 +192,12 @@ EXPORT_SYMBOL_GPL(__percpu_down_read); __sum; \ }) +bool percpu_is_read_locked(struct percpu_rw_semaphore *sem) +{ + return per_cpu_sum(*sem->read_count) != 0 && !atomic_read(&sem->block); +} +EXPORT_SYMBOL_GPL(percpu_is_read_locked); + /* * Return true if the modular sum of the sem->read_count per-CPU variable is * zero. If this sum is zero, then it is stable due to the fact that if any |