On Tue, Sep 18, 2018 at 05:50:21AM -0700, Tejun Heo wrote:

On Tue, Sep 18, 2018 at 06:19:44PM +0800, Ming Lei wrote:

quoted

Now percpu_ref_reinit() can only be done on one percpu refcounter when it
drops zero. And the limit shouldn't be so strict, and it is quite
straightforward that we can do it when the refcount doesn't drop zero
because it is at atomic mode.

This patch introduces percpu_ref_resurge() in which the above limit is
relaxed, so we may avoid extra change[1] for NVMe timeout's requirement.

For now,

Nacked-by: Tejun Heo [off-list ref]

Please see the original discussion thread.

Your comment in that thread supposes that synchronize_rcu() is used for
avoiding race with .release().

But this patchset doesn't use that approach at all for avoiding this
race.

Thanks,
Ming