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SubjectRe: [PATCH 1/5] pid: Implement task references.
Date
On Jan 30, 2006, at 00:46, Eric Dumazet wrote:
> 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.

OHHH, I see where I got confused. The indentation was bad, dunno if
it was my end or yours, so I misread it as this:

if (atomic_read(...) == 1) {
atomic_dec_and_test(...);
...
}

instead of this:

if (atomic_read(...) == 1 ||
atomic_dec_and_test(...)) {
...
}

This should teach me not to reply this late at night. Sorry for the
confusion.

Cheers,
Kyle Moffett

--
They _will_ find opposing experts to say it isn't, if you push hard
enough the wrong way. Idiots with a PhD aren't hard to buy.
-- Rob Landley



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