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| author | Eric Dumazet <dada1@cosmosbay.com> | 2006-01-30 06:19:35 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2006-03-20 13:42:57 -0800 |
| commit | 8b5536bbee53620f8d5f367987e5727ba36d886d (patch) | |
| tree | c4733f4ce2a6d1aab32eda3c096c97f0365a43f8 /lib | |
| parent | 489447380a2921ec0e9154f773c44ab3167ede4b (diff) | |
| download | lwn-8b5536bbee53620f8d5f367987e5727ba36d886d.tar.gz lwn-8b5536bbee53620f8d5f367987e5727ba36d886d.zip | |
[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')
| -rw-r--r-- | lib/kref.c | 7 |
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; } |