author: Tejun Heo <tj@kernel.org> 2015-09-29 17:47:20 -0400
committer: Tejun Heo <tj@kernel.org> 2016-08-10 15:02:58 -0400
commit: 33e465ce7cb30b71c113a26f36d293b545a28e12
parent: 3f49bdd95855a33eea749304d2e10530a869218b
Commit Summary:
Diffstat:
1 file changed, 21 insertions, 4 deletions
diff --git a/lib/percpu-refcount.c b/lib/percpu-refcount.c
index f3ff793691ac..c69938e4b0d5 100644
--- a/lib/percpu-refcount.c
+++ b/lib/percpu-refcount.c
@@ -33,6 +33,7 @@
#define PERCPU_COUNT_BIAS (1LU << (BITS_PER_LONG - 1))
+static DEFINE_SPINLOCK(percpu_ref_switch_lock);
static DECLARE_WAIT_QUEUE_HEAD(percpu_ref_switch_waitq);
static unsigned long __percpu *percpu_count_ptr(struct percpu_ref *ref)
@@ -208,15 +209,15 @@ static void __percpu_ref_switch_to_percpu(struct percpu_ref *ref)
static void __percpu_ref_switch_mode(struct percpu_ref *ref,
percpu_ref_func_t *confirm_switch)
{
+ lockdep_assert_held(&percpu_ref_switch_lock);
+
/*
* If the previous ATOMIC switching hasn't finished yet, wait for
* its completion. If the caller ensures that ATOMIC switching
* isn't in progress, this function can be called from any context.
- * Do an extra confirm_switch test to circumvent the unconditional
- * might_sleep() in wait_event().
*/
- if (ref->confirm_switch)
- wait_event(percpu_ref_switch_waitq, !ref->confirm_switch);
+ wait_event_lock_irq(percpu_ref_switch_waitq, !ref->confirm_switch,
+ percpu_ref_switch_lock);
if (ref->force_atomic || (ref->percpu_count_ptr & __PERCPU_REF_DEAD))
__percpu_ref_switch_to_atomic(ref, confirm_switch);
@@ -247,8 +248,14 @@ static void __percpu_ref_switch_mode(struct percpu_ref *ref,
void percpu_ref_switch_to_atomic(struct percpu_ref *ref,
percpu_ref_func_t *confirm_switch)
{
+ unsigned long flags;
+
+ spin_lock_irqsave(&percpu_ref_switch_lock, flags);
+
ref->force_atomic = true;
__percpu_ref_switch_mode(ref, confirm_switch);
+
+ spin_unlock_irqrestore(&percpu_ref_switch_lock, flags);
}
/**
@@ -271,8 +278,14 @@ void percpu_ref_switch_to_atomic(struct percpu_ref *ref,
*/
void percpu_ref_switch_to_percpu(struct percpu_ref *ref)
{
+ unsigned long flags;
+
+ spin_lock_irqsave(&percpu_ref_switch_lock, flags);
+
ref->force_atomic = false;
__percpu_ref_switch_mode(ref, NULL);
+
+ spin_unlock_irqrestore(&percpu_ref_switch_lock, flags);
}
/**
@@ -293,12 +306,18 @@ void percpu_ref_switch_to_percpu(struct percpu_ref *ref)
void percpu_ref_kill_and_confirm(struct percpu_ref *ref,
percpu_ref_func_t *confirm_kill)
{
+ unsigned long flags;
+
+ spin_lock_irqsave(&percpu_ref_switch_lock, flags);
+
WARN_ONCE(ref->percpu_count_ptr & __PERCPU_REF_DEAD,
"%s called more than once on %pf!", __func__, ref->release);
ref->percpu_count_ptr |= __PERCPU_REF_DEAD;
__percpu_ref_switch_mode(ref, confirm_kill);
percpu_ref_put(ref);
+
+ spin_unlock_irqrestore(&percpu_ref_switch_lock, flags);
}
EXPORT_SYMBOL_GPL(percpu_ref_kill_and_confirm);
@@ -315,10 +334,16 @@ EXPORT_SYMBOL_GPL(percpu_ref_kill_and_confirm);
*/
void percpu_ref_reinit(struct percpu_ref *ref)
{
+ unsigned long flags;
+
+ spin_lock_irqsave(&percpu_ref_switch_lock, flags);
+
WARN_ON_ONCE(!percpu_ref_is_zero(ref));
ref->percpu_count_ptr &= ~__PERCPU_REF_DEAD;
percpu_ref_get(ref);
__percpu_ref_switch_mode(ref, NULL);
+
+ spin_unlock_irqrestore(&percpu_ref_switch_lock, flags);
}
EXPORT_SYMBOL_GPL(percpu_ref_reinit);