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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] percpu-refcount: relax limit on percpu_ref_reinit()
Date: Wed, 12 Sep 2018 00:05:33 +0800	[thread overview]
Message-ID: <20180911160532.GB10082@ming.t460p> (raw)
In-Reply-To: <20180911154959.GI1100574@devbig004.ftw2.facebook.com>

On Tue, Sep 11, 2018 at 08:49:59AM -0700, Tejun Heo wrote:
> On Tue, Sep 11, 2018 at 11:45:41PM +0800, Ming Lei wrote:
> > > So, this part seems wrong.  The function is called percpu_ref_reinit()
> > > - the refcnt is expected to be in its initial state with just the base
> > > ref once this function returns.  If you're removing the restriction on
> > 
> > But the comment says that 'Re-initialize @ref so that it's in the same
> > state as when it finished', and this invariant isn't changed with this
> > patch.
> 
> The comment goes "when perpcu_ref_init() finished".  The function is
> called re _init_.  It should put the ref in the initial state, right?

OK, I am fine to keep the behaviour for this API, will introduce a new helper
for NVMe.

However, it is doable to switch to percpu mode from atomic mode when it
doesn't drop to zero, looks like sort of perpcu_ref_reinit(inherit_old_refcount).

Thanks,
Ming

  reply	other threads:[~2018-09-11 16:05 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-09-09 12:58 [PATCH] percpu-refcount: relax limit on percpu_ref_reinit() Ming Lei
2018-09-09 18:46 ` Bart Van Assche
2018-09-09 23:59   ` Ming Lei
2018-09-10  1:40 ` jianchao.wang
2018-09-10 16:11   ` Ming Lei
2018-09-11  1:48     ` jianchao.wang
2018-09-11  4:03       ` Ming Lei
2018-09-11  4:40         ` jianchao.wang
2018-09-11  8:20           ` Ming Lei
2018-09-11 14:22             ` jianchao.wang
2018-09-11 13:44           ` Tejun Heo
2018-09-11 14:13             ` jianchao.wang
2018-09-10  1:54 ` jianchao.wang
2018-09-10 16:49 ` Tejun Heo
2018-09-11  0:00   ` Ming Lei
2018-09-11 13:48     ` Tejun Heo
2018-09-11 15:45       ` Ming Lei
2018-09-11 15:49         ` Tejun Heo
2018-09-11 16:05           ` Ming Lei [this message]
2018-09-11 16:30             ` Tejun Heo
2018-09-11 16:34               ` Ming Lei
2018-09-11 16:38                 ` Tejun Heo
2018-09-12  1:52                   ` Ming Lei
2018-09-12 15:53                     ` Tejun Heo
2018-09-12 22:11                       ` Ming Lei
2018-09-18 12:49                         ` Tejun Heo
2018-09-19  2:51                           ` Ming Lei
2018-09-19 20:36                             ` Tejun Heo
2018-09-18  3:21 ` jianchao.wang
2018-09-18  7:34   ` Ming Lei

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