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Message-ID: <50b20a3e-e264-4788-8e52-f7b57cf944f0@acm.org>
Date:   Fri, 22 Sep 2023 08:23:15 -0700
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Subject: Re: [PATCH 1/2] scsi: core: scsi_device_online() return false if
 state is SDEV_CANCEL
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To:     Wenchao Hao <haowenchao2@huawei.com>,
        "James E . J . Bottomley" <jejb@linux.ibm.com>,
        "Martin K . Petersen" <martin.petersen@oracle.com>,
        open-iscsi@googlegroups.com, linux-scsi@vger.kernel.org
Cc:     linux-kernel@vger.kernel.org, louhongxiang@huawei.com
References: <20230922093636.2645961-1-haowenchao2@huawei.com>
 <20230922093636.2645961-2-haowenchao2@huawei.com>
From:   Bart Van Assche <bvanassche@acm.org>
In-Reply-To: <20230922093636.2645961-2-haowenchao2@huawei.com>
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On 9/22/23 02:36, Wenchao Hao wrote:
> SDEV_CANCEL is set when removing device and scsi_device_online() should
> return false if sdev_state is SDEV_CANCEL.
> 
> IO hang would be caused if return true when state is SDEV_CANCEL with
> following order:
> 
> T1:					    T2:scsi_error_handler
> __scsi_remove_device()
>    scsi_device_set_state(sdev, SDEV_CANCEL)
>    					    scsi_eh_flush_done_q()
> 					    if (scsi_device_online(sdev))
> 					      scsi_queue_insert(scmd,...)
> 
> The command added by scsi_queue_insert() would never be handled any
> more.

Why not? I think the blk_mq_destroy_queue() call in 
__scsi_remove_device() will cause it to fail.

Thanks,

Bart.