Messages in this thread Patch in this message | | | Subject | [PATCH 06/23] kref: avoid an atomic operation in kref_put() | Date | Mon, 20 Mar 2006 14:00:38 -0800 | From | Greg Kroah-Hartman <> |
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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>
---
lib/kref.c | 7 ++++++- 1 files changed, 6 insertions(+), 1 deletions(-)
8b5536bbee53620f8d5f367987e5727ba36d886d diff --git a/lib/kref.c b/lib/kref.c index 0d07cc3..4a467fa 100644 --- a/lib/kref.c +++ b/lib/kref.c @@ -52,7 +52,12 @@ int kref_put(struct kref *kref, void (*r 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; } -- 1.2.4
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