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From: Keith Busch <kbusch@kernel.org>
To: Christoph Hellwig <hch@lst.de>
Cc: Judy Brock <judy.brock@samsung.com>,
	Edmund Nadolski <edmund.nadolski@intel.com>,
	Sagi Grimberg <sagi@grimberg.me>,
	linux-nvme@lists.infradead.org,
	James Smart <james.smart@broadcom.com>
Subject: Re: [PATCHv3 4/5] nvme: Prevent resets during paused controller state
Date: Fri, 11 Oct 2019 01:17:27 +0900
Message-ID: <20191010161727.GA22430@washi1.fujisawa.hgst.com> (raw)
In-Reply-To: <20191010160911.GA1868@lst.de>

On Thu, Oct 10, 2019 at 06:09:11PM +0200, Christoph Hellwig wrote:
> On Fri, Oct 11, 2019 at 01:05:26AM +0900, Keith Busch wrote:
> > +/*
> > + * Use this function to proceed with scheduling reset_work for a controller
> > + * that had previously been set to the resetting state. This is intended for
> > + * code paths that can't be interrupted by other reset attempts.
> > + */
> > +static int nvme_reset_schedule(struct nvme_ctrl *ctrl)
> > +{
> > +	if (ctrl->state != NVME_CTRL_RESETTING)
> > +		return -EBUSY;
> > +	if (!queue_work(nvme_reset_wq, &ctrl->reset_work))
> > +		return -EBUSY;
> > +	return 0;
> > +}
> > +
> >  int nvme_reset_ctrl(struct nvme_ctrl *ctrl)
> >  {
> >  	if (!nvme_change_ctrl_state(ctrl, NVME_CTRL_RESETTING))
> > @@ -3829,13 +3843,13 @@ static void nvme_fw_act_work(struct work_struct *work)
> >  		if (time_after(jiffies, fw_act_timeout)) {
> >  			dev_warn(ctrl->device,
> >  				"Fw activation timeout, reset controller\n");
> > -			nvme_reset_ctrl(ctrl);
> > -			break;
> > +			nvme_reset_schedule(ctrl);
> > +			return;
> 
> I don't really see a point in that nvme_reset_schedule helper,
> especially as the name is a little confusing.  Moving the comment here
> and just open coding a
> 
> 			if (ctrl->state == NVME_CTRL_RESETTING)
> 				queue_work(nvme_reset_wq, &ctrl->reset_work))
> 
> would seem much more obvious and matches the nvme_handle_aen_notice
> side.

Until a moment ago, I thought nvme_reset_wq was a local static, which is
why I needed to provide an exportable function so drivers can schedule on
it. I see now that symbolis exported for some reason despite no external
users, but since it is exported, we can duplicate this "if (RESETTING)
queue_work()" stuff from the pci driver.

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Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-10 16:05 [PATCHv3 0/5] nvme: double reset prevention Keith Busch
2019-10-10 16:05 ` [PATCHv3 1/5] nvme-pci: Free tagset if no IO queues Keith Busch
2019-10-10 16:05 ` [PATCHv3 2/5] nvme: Remove ADMIN_ONLY state Keith Busch
2019-10-10 16:05 ` [PATCHv3 3/5] nvme: Restart request timers in resetting state Keith Busch
2019-10-10 16:05 ` [PATCHv3 4/5] nvme: Prevent resets during paused controller state Keith Busch
2019-10-10 16:09   ` Christoph Hellwig
2019-10-10 16:17     ` Keith Busch [this message]
2019-10-10 16:05 ` [PATCHv3 5/5] nvme: Wait for reset state when required Keith Busch
2019-10-10 16:18   ` Christoph Hellwig
2019-10-10 16:30     ` Keith Busch

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