Hello,

On Mon, Feb 20, 2017 at 12:19:01PM +0200, Elena Reshetova wrote:
> @@ -134,10 +135,13 @@ static inline void put_css_set(struct css_set *cset)
>        * can see it. Similar to atomic_dec_and_lock(), but for an
>        * rwlock
>        */
> -     if (atomic_add_unless(&cset->refcount, -1, 1))
> +     spin_lock_irqsave(&css_set_lock, flags);
> +     if (refcount_read(&cset->refcount) != 1) {
> +             WARN_ON(refcount_dec_and_test(&cset->refcount));
> +             spin_unlock_irqrestore(&css_set_lock, flags);
>               return;
> +     }

This isn't an equivalent conversion and should have been mentioned in
the patch description.  Hmm... and I'm not sure this is a good idea.
Can't we add the matching operation on refcount_t rather than adding
extra locking like this?

Thanks.

-- 
tejun

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