On Thu, 7 Oct 2010 12:59:32 -0400
Jeff Layton <jlayton@xxxxxxxxxx> wrote:
>
> For instance:
>
> + if (!atomic_dec_and_lock(&cifs_file->count, &cifs_file_list_lock))
> + return;
> +
> + /* count can be incremented inside the lock, so must check again */
> + if (atomic_read(&cifs_file->count) > 0) {
> + spin_unlock(&cifs_file_list_lock);
> + return;
> + }
>
...oh and to make matters worse, the above code is still racy if the
count can be incremented outside the lock too.
I think we need to try to keep this code as simple as possible with
clear, unambiguous locking rules around a simple counter.
--
Jeff Layton <jlayton@xxxxxxxxx>
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