linux-kernel - Re: [PATCH] SCSI: run queue if SCSI device queue isn't ready and queue is idle

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Date:   Tue, 5 Dec 2017 16:16:44 +0000
From:   Bart Van Assche <Bart.VanAssche@....com>
To:     "osandov@...ndov.com" <osandov@...ndov.com>,
        "jthumshirn@...e.de" <jthumshirn@...e.de>,
        "ming.lei@...hat.com" <ming.lei@...hat.com>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-block@...r.kernel.org" <linux-block@...r.kernel.org>,
        "hch@...radead.org" <hch@...radead.org>,
        "martin.petersen@...cle.com" <martin.petersen@...cle.com>,
        "linux-scsi@...r.kernel.org" <linux-scsi@...r.kernel.org>,
        "axboe@...com" <axboe@...com>, "hare@...e.com" <hare@...e.com>,
        "holger@...lied-asynchrony.com" <holger@...lied-asynchrony.com>,
        "jejb@...ux.vnet.ibm.com" <jejb@...ux.vnet.ibm.com>
Subject: Re: [PATCH] SCSI: run queue if SCSI device queue isn't ready and
 queue is idle

On Tue, 2017-12-05 at 15:29 +0100, Johannes Thumshirn wrote:
> 1) Testing without the patch applied hangs the test forever as it
>    doesn't get killed after a specific timeout (I think this should be
>    solved in a common function).

Hello Johannes,

If a request queue got stuck then the processes that submitted the requests
on that queue are unkillable. The only approach I know of to stop these
processes is to send a kill signal and next to trigger a queue run from user
space. One possible approach is to run the following command:

    for d in /sys/kernel/debug/block/*; do echo kick >$d/state; done

Bart.