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locking/atomic, kref: Implement kref_put_lock()

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Because home-rolling your own is _awesome_, stop doing it. Provide
kref_put_lock(), just like kref_put_mutex() but for a spinlock.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Peter Zijlstra
2016-11-14 18:03:11 +01:00
committed by Ingo Molnar
parent 23b19ec337
commit 0a13cd1a05
2 changed files with 26 additions and 11 deletions
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22
include/linux/kref.h
View File

@@ -19,6 +19,7 @@
#include <linux/atomic.h>
#include <linux/kernel.h>
#include <linux/mutex.h>
#include <linux/spinlock.h>
struct kref {
atomic_t refcount;
@@ -86,12 +87,21 @@ static inline int kref_put_mutex(struct kref *kref,
struct mutex *lock)
{
WARN_ON(release == NULL);
if (unlikely(!atomic_add_unless(&kref->refcount, -1, 1))) {
mutex_lock(lock);
if (unlikely(!atomic_dec_and_test(&kref->refcount))) {
mutex_unlock(lock);
return 0;
}
if (atomic_dec_and_mutex_lock(&kref->refcount, lock)) {
release(kref);
return 1;
}
return 0;
}
static inline int kref_put_lock(struct kref *kref,
void (*release)(struct kref *kref),
spinlock_t *lock)
{
WARN_ON(release == NULL);
if (atomic_dec_and_lock(&kref->refcount, lock)) {
release(kref);
return 1;
}