Messages in this thread | | | Date | Tue, 25 Apr 2006 12:34:10 +0800 | From | Akinobu Mita <> | Subject | Re: [patch 1/4] kref: warn kref_put() with unreferenced kref |
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On Mon, Apr 24, 2006 at 08:51:28PM -0700, Greg KH wrote: > > @@ -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.
The idea of detection kref_put() with unreferenced object was stolen from BUG_ON()es in blocks/ll_rw_blk.c and fs/bio.c
ll_rw_blk.c: BUG_ON(atomic_read(&ioc->refcount) == 0);
bio.c: BIO_BUG_ON(!atomic_read(&bio->bi_cnt));
But the kref counter usually does not become zero. Because kref is trying to reduce the number of atomic_dec_and_test()
So this patch also set kref counter to zero here:
> > + if (atomic_read(&kref->refcount) == 1) > > + atomic_set(&kref->refcount, 0);
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