linux-kernel - Re: [PATCH V2 1/1] nvme: fix multiple ctrl removal scheduling

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Date:   Tue, 30 May 2017 14:58:06 +0300
From:   Sagi Grimberg <sagi@...mberg.me>
To:     Keith Busch <keith.busch@...el.com>,
        Rakesh Pandit <rakesh@...era.com>
Cc:     linux-nvme@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Jens Axboe <axboe@...com>, Christoph Hellwig <hch@....de>
Subject: Re: [PATCH V2 1/1] nvme: fix multiple ctrl removal scheduling


>> Allowing multiple resets can result in multiple controller removal as
>> well if different conditions inside nvme_reset_work fail and which
>> might deadlock on device_release_driver.
>>
>> This patch makes sure that work queue item (reset_work) is added only
>> if controller state != NVME_CTRL_RESETTING and that is achieved by
>> moving state change outside nvme_reset_work into nvme_reset and
>> removing old work_busy call.  State change is always synchronizated
>> using controller spinlock.
>
> So, the reason the state is changed when the work is running rather than
> queueing is for the window when the state may be set to NVME_CTRL_DELETING,
> and we don't want the reset work to proceed in that case.
>
> What do you think about adding a new state, like NVME_CTRL_SCHED_RESET,
> then leaving the NVME_CTRL_RESETTING state change as-is?

OK, just got to this one.

Instead of adding yet another state, how about making controller delete
cancel the reset_work (cancel_work_sync)?