linux-kernel - Re: [PATCH v2 2/2] nvme: handle persistent internal error AER from NVMe controller

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Date:   Mon, 6 Jun 2022 08:51:02 +0200
From:   "hch@....de" <hch@....de>
To:     "Michael Kelley (LINUX)" <mikelley@...rosoft.com>
Cc:     Keith Busch <kbusch@...nel.org>, "axboe@...com" <axboe@...com>,
        "hch@....de" <hch@....de>, "sagi@...mberg.me" <sagi@...mberg.me>,
        "linux-nvme@...ts.infradead.org" <linux-nvme@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Caroline Subramoney <Caroline.Subramoney@...rosoft.com>,
        Richard Wurdack <riwurd@...rosoft.com>,
        Nathan Obr <Nathan.Obr@...rosoft.com>
Subject: Re: [PATCH v2 2/2] nvme: handle persistent internal error AER from
 NVMe controller

On Sat, Jun 04, 2022 at 02:28:11PM +0000, Michael Kelley (LINUX) wrote:
> > driver's irq handler. The other transports block on register reads, though, so
> > they can't call this from an atomic context. The TCP context looks safe, but
> > I'm not sure about RDMA or FC.
> 
> Good point.  But even if the RDMA and FC contexts are safe,

For RDMA this is typically called from softirq context, so it is indeed
not save.

> if a
> persistent error is reported, the controller is already in trouble and
> may not respond to a request to retrieve the CSTS anyway.  Perhaps
> we should just trust the AER error report and not bother checking
> CSTS to decide whether to do the reset.  We can still check ctrl->state
> and skip the reset if there's already one in progress.

Yes, that might be a better option.