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Message-ID: <8057d66f-4f0b-4f03-8401-51c85ac27f41@oracle.com>
Date:   Mon, 25 Sep 2023 11:52:26 -0500
User-Agent: Mozilla Thunderbird
Subject: Re: [RFC PATCH v2 00/18] scsi: scsi_error: Introduce new error handle
 mechanism
Content-Language: en-US
To:     Wenchao Hao <haowenchao2@huawei.com>,
        "James E . J . Bottomley" <jejb@linux.ibm.com>,
        "Martin K . Petersen" <martin.petersen@oracle.com>,
        linux-scsi@vger.kernel.org
Cc:     Hannes Reinecke <hare@suse.de>, linux-kernel@vger.kernel.org,
        louhongxiang@huawei.com, lixiaokeng@huawei.com
References: <20230901094127.2010873-1-haowenchao2@huawei.com>
 <bfc9e734-3a04-9600-58e7-91d7e7f53010@huawei.com>
From:   Mike Christie <michael.christie@oracle.com>
In-Reply-To: <bfc9e734-3a04-9600-58e7-91d7e7f53010@huawei.com>
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On 9/14/23 1:20 AM, Wenchao Hao wrote:
> On 2023/9/1 17:41, Wenchao Hao wrote:
>> It's unbearable for systems with large scale scsi devices share HBAs to
>> block all devices' IOs when handle error commands, we need a new error
>> handle mechanism to address this issue.
>>
>> I consulted about this issue a year ago, the discuss link can be found in
>> refenence. Hannes replied about why we have to block the SCSI host
>> then perform error recovery kindly. I think it's unnecessary to block
>> SCSI host for all drivers and can try a small level recovery(LUN based for
>> example) first to avoid block the SCSI host.
>>
>> The new error handle mechanism introduced in this patchset has been
>> developed and tested with out self developed hardware since one year
>> ago, now we want this mechanism can be used by more drivers.
>>
>> Drivers can decide if using the new error handle mechanism and how to
>> handle error commands when scsi_device are scanned,the new mechanism
>> makes SCSI error handle more flexible.
>>
>> SCSI error recovery strategy after blocking host's IO is mainly
>> following steps:
>>
>> - LUN reset
>> - Target reset
>> - Bus reset
>> - Host reset
>>
> 
> Mike gave some suggestions and I found a bug in fallback logic, I would
> address these and resend in next few days.

Please wait to resend. I'm still reviewing the patches. When I commented
last time I just did a quick look over to get an idea for the design and
what your goals were.