linux-kernel - Re: [PATCH]nvme-pci: Fixes EEH failure on ppc

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Message-ID: <20180207012353.GD13470@ming.t460p>
Date:   Wed, 7 Feb 2018 09:24:37 +0800
From:   Ming Lei <ming.lei@...hat.com>
To:     wenxiong <wenxiong@...ux.vnet.ibm.com>
Cc:     Keith Busch <keith.busch@...el.com>, wenxiong@...inux.vnet.ibm.com,
        linux-nvme@...ts.infradead.org, axboe@...com,
        linux-kernel@...r.kernel.org, wenxiong@...ibm.com
Subject: Re: [PATCH]nvme-pci: Fixes EEH failure on ppc

On Tue, Feb 06, 2018 at 02:01:05PM -0600, wenxiong wrote:
> On 2018-02-06 10:33, Keith Busch wrote:
> > On Mon, Feb 05, 2018 at 03:49:40PM -0600, wenxiong@...inux.vnet.ibm.com
> > wrote:
> > > @@ -1189,6 +1183,12 @@ static enum blk_eh_timer_return
> > > nvme_timeout(struct request *req, bool reserved)
> > >  	struct nvme_command cmd;
> > >  	u32 csts = readl(dev->bar + NVME_REG_CSTS);
> > > 
> > > +	/* If PCI error recovery process is happening, we cannot reset or
> > > +	 * the recovery mechanism will surely fail.
> > > +	 */
> > > +	if (pci_channel_offline(to_pci_dev(dev->dev)))
> > > +		return BLK_EH_HANDLED;
> > > +
> > 
> > This patch will tell the block layer to complete the request and
> > consider
> > it a success, but it doesn't look like the command actually completed at
> > all. You're going to get data corruption this way, right? Is returning
> > BLK_EH_HANDLED immediately really the right thing to do here?
> 
> Hi Ming,
> 
> Can you help checking if it is ok if returning BLK_EH_HANDLEDED in this
> case?

Hi Wenxiong,

Looks Keith is correct, and this timed out request will be completed by
block layer and NVMe driver if BLK_EH_HANDLED is returned, but this IO
isn't completed actually, so either data loss(write) or read failure is
caused.

Maybe BLK_EH_RESET_TIMER is fine under this situation.

Thanks,
Ming