From: Ming Lei <ming.lei@redhat.com>
To: Tejun Heo <tj@kernel.org>
Cc: linux-kernel@vger.kernel.org,
Jianchao Wang <jianchao.w.wang@oracle.com>,
Kent Overstreet <kent.overstreet@gmail.com>,
linux-block@vger.kernel.org
Subject: Re: [PATCH 2/4] lib/percpu-refcount: introduce percpu_ref_resurge()
Date: Wed, 19 Sep 2018 11:09:10 +0800 [thread overview]
Message-ID: <20180919030909.GC20560@ming.t460p> (raw)
In-Reply-To: <20180918125021.GB902964@devbig004.ftw2.facebook.com>
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:
> > 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 <tj@kernel.org>
>
> 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
next prev parent reply other threads:[~2018-09-19 8:45 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-18 10:19 [PATCH 0/4] blk-mq: allow to unfreeze queue when io isn't drained Ming Lei
2018-09-18 10:19 ` [PATCH 1/4] percpu-refcount: move zeroing of percpu part into percpu_ref_switch_to_atomic_rcu Ming Lei
2018-09-18 10:19 ` [PATCH 2/4] lib/percpu-refcount: introduce percpu_ref_resurge() Ming Lei
2018-09-18 12:50 ` Tejun Heo
2018-09-19 3:09 ` Ming Lei [this message]
2018-09-19 5:19 ` jianchao.wang
2018-09-19 7:55 ` Ming Lei
2018-09-19 8:01 ` Ming Lei
2018-09-18 10:19 ` [PATCH 3/4] blk-mq: introduce blk_mq_unfreeze_queue_no_drain_io Ming Lei
2018-09-18 10:19 ` Ming Lei
2018-09-18 10:19 ` [PATCH 4/4] nvme: don't drain IO in nvme_reset_work() Ming Lei
2018-09-18 10:19 ` Ming Lei
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