linux-kernel - Re: [PATCH] null_blk: allow teardown on request timeout

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Message-ID: <f2baa3b4-81c9-a6d8-0c26-3e695dad5d10@acm.org>
Date:   Mon, 17 Oct 2022 07:21:17 -0700
From:   Bart Van Assche <bvanassche@....org>
To:     Chaitanya Kulkarni <kch@...dia.com>, linux-block@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     axboe@...nel.dk, damien.lemoal@...nsource.wdc.com,
        johannes.thumshirn@....com, ming.lei@...hat.com,
        shinichiro.kawasaki@....com, vincent.fu@...sung.com,
        yukuai3@...wei.com
Subject: Re: [PATCH] null_blk: allow teardown on request timeout

On 10/15/22 22:20, Chaitanya Kulkarni wrote:
> In current timeout implementation null_blk just completes the request
> with error=BLK_STS_TIMEOUT without doing any cleanup, hence device
> cleanup code including handling inflight requests on timeout and
> teardown is never exercised.

Hi Chaitanya,

How about removing that code instead of adding a mechanism for 
triggering it?

> Add a module parameter rq_abort_limit to allow null_blk perform device
> cleanup when time out occurs. The non zero value of this parameter
> allows user to set the number of timeouts to occur before triggering
> cleanup/teardown work.

As Ming Lei wrote, there are no other block drivers that destroy 
themselves if a certain number of timeouts occur. It seems weird to me 
to trigger self-removal from inside a timeout handler.

Thanks,

Bart.