Kyle Moffett a écrit :
On Jan 30, 2006, at 00:19, Eric Dumazet wrote:
- 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) ||
Uhh, I think you got this test reversed. Didn't you mean != 1?
Otherwise you only do the dec_and_test when the refcount is one, which
means that you leak everything kref-ed.
Not at all :)
Your mail is just another proof why kref is a good abstraction :)
If you are the last user of a kref, (refcount = 1), then
you are sure that nobody else but you is using the object, and as we are
kref_put() this object, the atomic_dec_and-test *will* set the count the
object and you are going to release() object.
The release() function is not going to look at kref_count again, just free the
resources and the object.
Maybe a change in the documentation is necessary to explain this point
(release() can e called while the apparent krefcount is 1)
Or in kref_put doing this :
if (atomic_read(&kref->refcount) == 1) {
atomic_set(&kref->refcount, 0);
release(kref);
}
if (atomic_dec_and_test(&kref->refcount)) {
release(kref);
return 1;
}
Eric
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