[PATCH v2 09/13] locking/percpu-rwsem: Add percpu_is_write_locked() and percpu_is_read_locked()
From: Marco Elver <elver@google.com>
Date: 2022-06-28 10:00:11
Also in:
linux-perf-users, linux-sh, lkml
Subsystem:
locking primitives, per-cpu memory allocator, the rest · Maintainers:
Peter Zijlstra, Ingo Molnar, Will Deacon, Boqun Feng, Dennis Zhou, Tejun Heo, Christoph Lameter, Linus Torvalds
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> --- v2: * New patch. --- include/linux/percpu-rwsem.h | 6 ++++++ kernel/locking/percpu-rwsem.c | 6 ++++++ 2 files changed, 12 insertions(+)
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..213d114fb025 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; +} +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
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2.37.0.rc0.161.g10f37bed90-goog