linux-kernel - Re: [PATCH V2] nvme: fix nvme_remove going to uninterruptible sleep for ever

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Message-ID: <20170605081817.GA22122@lst.de>
Date:   Mon, 5 Jun 2017 10:18:17 +0200
From:   Christoph Hellwig <hch@....de>
To:     Sagi Grimberg <sagi@...mberg.me>
Cc:     Christoph Hellwig <hch@....de>, Rakesh Pandit <rakesh@...era.com>,
        linux-nvme@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Jens Axboe <axboe@...com>, Keith Busch <keith.busch@...el.com>,
        Andy Lutomirski <luto@...nel.org>
Subject: Re: [PATCH V2] nvme: fix nvme_remove going to uninterruptible
        sleep for ever

On Sun, Jun 04, 2017 at 06:28:15PM +0300, Sagi Grimberg wrote:
>
>> I think we need the NVME_CTRL_SCHED_RESET state.  In fact I'm pretty
>> sure some time in the past I already had it in a local tree as a
>> generalization of rdma and loop already use NVME_CTRL_RESETTING
>> (they set it before queueing the reset work).
>
> I don't remember having it, but I might be wrong...
>
> Can you explain again why you think we need it? Sorry for being
> difficult, but I'm not exactly sure why it makes things better
> or simpler.

Motly that we can treat a controller as under reset before scheduling
the reset work, both to prevent multiple schedules, and to make
checks like the one in nvme_should_reset robus.

But I think something along the lines of the earlier patch from
Rakesh that just sets the RESETTING state earlier + the cancel_work_sync
suggested by you should also work for that purpose.  So maybe that's
the way to go after all.