linux-kernel - Re: [REQUEST DISCUSS]: speed up SCSI error handle for host with massive devices

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Date:   Wed, 6 Apr 2022 17:40:52 +0800
From:   Wenchao Hao <haowenchao@...wei.com>
To:     Hannes Reinecke <hare@...e.de>,
        Mike Christie <michael.christie@...cle.com>,
        Steffen Maier <maier@...ux.ibm.com>,
        <linux-scsi@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        Lee Duncan <lduncan@...e.com>,
        John Garry <john.garry@...wei.com>
CC:     Wu Bo <wubo40@...wei.com>, Feilong Lin <linfeilong@...wei.com>,
        <zhangjian013@...wei.com>
Subject: Re: [REQUEST DISCUSS]: speed up SCSI error handle for host with
 massive devices

On 2022/4/4 13:28, Hannes Reinecke wrote:
> On 4/3/22 19:17, Mike Christie wrote:
>> On 4/3/22 12:14 PM, Mike Christie wrote:
>>> We could share code with scsi_ioctl_reset as well. Drivers that support
>>> TMFs via that ioctl already expect queuecommand to be possibly in the
>>> middle of a run and IO not yet timed out. For example, the code to
>>> block a queue and reset the device could be used for the new EH and
>>> SG_SCSI_RESET_DEVICE handling.
>>>
>>
>> Hannes or others,
>>
>> How do parallel SCSI drivers support scsi_ioctl_reset? Is is not fully
>> supported and more only used for controlled testing?
> 
> That's actually a problem in scsi_ioctl_reset(); it really should wait for all I/O to quiesce. Currently it just sets the 'tmf' flag and calls into the various reset functions.
> 
> But really, I'd rather get my EH rework in before we're start discussing modifying EH behaviour.
> Let me repost it ...
> 

Would you take fast EH(such as single LUN reset) into consideration, maybe
a second but lightweight EH? It means a lot.

Or give a way drivers can branch out the general timeout and EH handle logic?