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authorEric Dumazet <dada1@cosmosbay.com>2006-01-30 06:19:35 +0100
committerGreg Kroah-Hartman <gregkh@suse.de>2006-03-20 13:42:57 -0800
commit8b5536bbee53620f8d5f367987e5727ba36d886d (patch)
treec4733f4ce2a6d1aab32eda3c096c97f0365a43f8 /lib/kref.c
parent489447380a2921ec0e9154f773c44ab3167ede4b (diff)
downloadlinux-linaro-stable-8b5536bbee53620f8d5f367987e5727ba36d886d.tar.gz
[PATCH] kref: avoid an atomic operation in kref_put()
Avoid an atomic operation in kref_put() when the last reference is dropped. On most platforms, atomic_read() is a plan read of the counter and involves no atomic at all. Signed-off-by: Eric Dumazet <dada1@cosmosbay.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'lib/kref.c')
-rw-r--r--lib/kref.c7
1 files changed, 6 insertions, 1 deletions
diff --git a/lib/kref.c b/lib/kref.c
index 0d07cc31c818..4a467faf1367 100644
--- a/lib/kref.c
+++ b/lib/kref.c
@@ -52,7 +52,12 @@ int kref_put(struct kref *kref, void (*release)(struct kref *kref))
WARN_ON(release == NULL);
WARN_ON(release == (void (*)(struct kref *))kfree);
- if (atomic_dec_and_test(&kref->refcount)) {
+ /*
+ * if current count is one, we are the last user and can release object
+ * right now, avoiding an atomic operation on 'refcount'
+ */
+ if ((atomic_read(&kref->refcount) == 1) ||
+ (atomic_dec_and_test(&kref->refcount))) {
release(kref);
return 1;
}