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From: Tejun Heo <tj@kernel.org>
To: Bart Van Assche <Bart.VanAssche@wdc.com>
Cc: "hch@lst.de" <hch@lst.de>, "neilb@suse.com" <neilb@suse.com>,
	"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
	"cl@linux.com" <cl@linux.com>,
	"axboe@kernel.dk" <axboe@kernel.dk>
Subject: Re: [PATCH 1/5] percpu-refcount: Introduce percpu_ref_switch_to_atomic_nowait()
Date: Mon, 11 Sep 2017 10:20:56 -0700	[thread overview]
Message-ID: <20170911172056.GG1774378@devbig577.frc2.facebook.com> (raw)
In-Reply-To: <1505148959.2802.47.camel@wdc.com>

Hey,

On Mon, Sep 11, 2017 at 04:55:59PM +0000, Bart Van Assche wrote:
> > Probably but that sounds really hairy.  I'd much prefer if it could be
> > done through the usual kill / confirm / release and re-init.  That's
> > not a possibility?
> 
> Modifying this patch series such that it uses the confirmation mechanism
> when switching from per-cpu to atomic mode should be possible. However, the
> wait_event_lock_irq() call in __percpu_ref_switch_mode() is annoying when
> calling percpu_ref_kill_and_confirm() from atomic context. How about adding
> a nowait version of percpu_ref_kill_and_confirm() that returns a boolean
> indicating whether or not this function succeeded?

Hmm... so if you know that you won't try to switch again while
switching is in progress, it should be fine.  That can't be
guaranteed?

Thanks.

-- 
tejun

  reply	other threads:[~2017-09-11 17:20 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-09-08 23:52 [PATCH 0/5] Make SCSI device suspend work reliably Bart Van Assche
2017-09-08 23:52 ` [PATCH 1/5] percpu-refcount: Introduce percpu_ref_switch_to_atomic_nowait() Bart Van Assche
2017-09-11  8:42   ` Johannes Thumshirn
2017-09-11 16:10     ` Bart Van Assche
2017-09-11 13:13   ` Tejun Heo
2017-09-11 16:09     ` Bart Van Assche
2017-09-11 16:37       ` tj
2017-09-11 16:55         ` Bart Van Assche
2017-09-11 17:20           ` Tejun Heo [this message]
2017-09-11 17:29             ` Bart Van Assche
2017-09-08 23:52 ` [PATCH 2/5] scsi: Change the type of the second last argument of scsi_execute() Bart Van Assche
2017-09-08 23:52 ` [PATCH 3/5] block: Introduce REQ_PM and remove RQF_PM Bart Van Assche
2017-09-08 23:52 ` [PATCH 4/5] block: Make SCSI device suspend work reliably Bart Van Assche
2017-09-12  2:29   ` Ming Lei
2017-09-12 15:45     ` Bart Van Assche
2017-09-12 16:10       ` Ming Lei
2017-09-12 16:25   ` Ming Lei
2017-09-08 23:52 ` [PATCH 5/5] blk-mq: Implement power management support Bart Van Assche
2017-09-12  9:14   ` Ming Lei
2017-09-09 10:39 ` [PATCH 0/5] Make SCSI device suspend work reliably Ming Lei
2017-09-11 16:25   ` Bart Van Assche
2017-09-12  2:17     ` Ming Lei

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