On Mon, Apr 24, 2006 at 04:33:34PM +0800, Akinobu Mita wrote:
> This patch adds warning to detect kref_put() with unreferenced kref.
>
> Signed-off-by: Akinobu Mita <[email protected]>
>
> lib/kref.c | 14 ++++++++------
> 1 files changed, 8 insertions(+), 6 deletions(-)
>
> Index: 2.6-git/lib/kref.c
> ===================================================================
> --- 2.6-git.orig/lib/kref.c
> +++ 2.6-git/lib/kref.c
> @@ -49,6 +49,7 @@ void kref_get(struct kref *kref)
> */
> int kref_put(struct kref *kref, void (*release)(struct kref *kref))
> {
> + WARN_ON(atomic_read(&kref->refcount) < 1);
How can this ever be true? If the refcount _ever_ goes below 1, the
object is freed.
> @@ -56,12 +57,13 @@ int kref_put(struct kref *kref, void (*r
> * 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;
> - }
> - return 0;
> + if (atomic_read(&kref->refcount) == 1)
> + atomic_set(&kref->refcount, 0);
> + else if (!atomic_dec_and_test(&kref->refcount))
> + return 0;
> +
> + release(kref);
> + return 1;
What does this change do? What are you trying to help out with?
CONFIG_DEBUG_SLAB will check to see if you reference krefs that have
already been freed.
thanks,
greg k -h
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