diff options
| -rw-r--r-- | include/linux/percpu-refcount.h | 25 | ||||
| -rw-r--r-- | lib/percpu-refcount.c | 14 |
2 files changed, 22 insertions, 17 deletions
diff --git a/include/linux/percpu-refcount.h b/include/linux/percpu-refcount.h index f015f139d491..d44b027f74fd 100644 --- a/include/linux/percpu-refcount.h +++ b/include/linux/percpu-refcount.h @@ -115,8 +115,10 @@ static inline bool __pcpu_ref_alive(struct percpu_ref *ref, * percpu_ref_get - increment a percpu refcount * @ref: percpu_ref to get * - * Analagous to atomic_inc(). - */ + * Analagous to atomic_long_inc(). + * + * This function is safe to call as long as @ref is between init and exit. + */ static inline void percpu_ref_get(struct percpu_ref *ref) { unsigned long __percpu *pcpu_count; @@ -138,12 +140,12 @@ static inline void percpu_ref_get(struct percpu_ref *ref) * Increment a percpu refcount unless its count already reached zero. * Returns %true on success; %false on failure. * - * The caller is responsible for ensuring that @ref stays accessible. + * This function is safe to call as long as @ref is between init and exit. */ static inline bool percpu_ref_tryget(struct percpu_ref *ref) { unsigned long __percpu *pcpu_count; - int ret = false; + int ret; rcu_read_lock_sched(); @@ -166,12 +168,13 @@ static inline bool percpu_ref_tryget(struct percpu_ref *ref) * Increment a percpu refcount unless it has already been killed. Returns * %true on success; %false on failure. * - * Completion of percpu_ref_kill() in itself doesn't guarantee that tryget - * will fail. For such guarantee, percpu_ref_kill_and_confirm() should be - * used. After the confirm_kill callback is invoked, it's guaranteed that - * no new reference will be given out by percpu_ref_tryget(). + * Completion of percpu_ref_kill() in itself doesn't guarantee that this + * function will fail. For such guarantee, percpu_ref_kill_and_confirm() + * should be used. After the confirm_kill callback is invoked, it's + * guaranteed that no new reference will be given out by + * percpu_ref_tryget_live(). * - * The caller is responsible for ensuring that @ref stays accessible. + * This function is safe to call as long as @ref is between init and exit. */ static inline bool percpu_ref_tryget_live(struct percpu_ref *ref) { @@ -196,6 +199,8 @@ static inline bool percpu_ref_tryget_live(struct percpu_ref *ref) * * Decrement the refcount, and if 0, call the release function (which was passed * to percpu_ref_init()) + * + * This function is safe to call as long as @ref is between init and exit. */ static inline void percpu_ref_put(struct percpu_ref *ref) { @@ -216,6 +221,8 @@ static inline void percpu_ref_put(struct percpu_ref *ref) * @ref: percpu_ref to test * * Returns %true if @ref reached zero. + * + * This function is safe to call as long as @ref is between init and exit. */ static inline bool percpu_ref_is_zero(struct percpu_ref *ref) { diff --git a/lib/percpu-refcount.c b/lib/percpu-refcount.c index 070dab5e7d77..8ef3f5c20df6 100644 --- a/lib/percpu-refcount.c +++ b/lib/percpu-refcount.c @@ -108,7 +108,6 @@ static void percpu_ref_kill_rcu(struct rcu_head *rcu) * reaching 0 before we add the percpu counts. But doing it at the same * time is equivalent and saves us atomic operations: */ - atomic_long_add((long)count - PCPU_COUNT_BIAS, &ref->count); WARN_ONCE(atomic_long_read(&ref->count) <= 0, @@ -120,8 +119,8 @@ static void percpu_ref_kill_rcu(struct rcu_head *rcu) ref->confirm_kill(ref); /* - * Now we're in single atomic_t mode with a consistent refcount, so it's - * safe to drop our initial ref: + * Now we're in single atomic_long_t mode with a consistent + * refcount, so it's safe to drop our initial ref: */ percpu_ref_put(ref); } @@ -134,8 +133,8 @@ static void percpu_ref_kill_rcu(struct rcu_head *rcu) * Equivalent to percpu_ref_kill() but also schedules kill confirmation if * @confirm_kill is not NULL. @confirm_kill, which may not block, will be * called after @ref is seen as dead from all CPUs - all further - * invocations of percpu_ref_tryget() will fail. See percpu_ref_tryget() - * for more details. + * invocations of percpu_ref_tryget_live() will fail. See + * percpu_ref_tryget_live() for more details. * * Due to the way percpu_ref is implemented, @confirm_kill will be called * after at least one full RCU grace period has passed but this is an @@ -145,8 +144,7 @@ void percpu_ref_kill_and_confirm(struct percpu_ref *ref, percpu_ref_func_t *confirm_kill) { WARN_ONCE(ref->pcpu_count_ptr & PCPU_REF_DEAD, - "percpu_ref_kill() called more than once on %pf!", - ref->release); + "%s called more than once on %pf!", __func__, ref->release); ref->pcpu_count_ptr |= PCPU_REF_DEAD; ref->confirm_kill = confirm_kill; @@ -172,7 +170,7 @@ void percpu_ref_reinit(struct percpu_ref *ref) int cpu; BUG_ON(!pcpu_count); - WARN_ON(!percpu_ref_is_zero(ref)); + WARN_ON_ONCE(!percpu_ref_is_zero(ref)); atomic_long_set(&ref->count, 1 + PCPU_COUNT_BIAS); |