Re: [PATCH v2 2/2] scsi: ufs: core: Decouple CQ sweep from request iterator in MCQ

[Bart Van Assche <bvanassche@acm.org>]

On 9/22/26 12:37 AM, Peter Wang wrote:
> On Mon, 2026-09-21 at 10:13 -0700, Bart Van Assche wrote:
>> In SDB mode, clearing UTRLDBR will cause all pending commands to be
>> requeued because the OCS member is initialized to
>> OCS_INVALID_COMMAND_STATUS and because ufshcd_transfer_rsp_status()
>> translates this status value into DID_REQUEUE << 16. I'm concerned
>> that this approach may cause the deadlines for SCSI commands to be
>> exceeded. Hence my proposal for MCQ mode not to requeue pending SCSI
>> commands but instead to let the SCSI error handler decide what to do
>> with these commands.
> 
> The current MCQ flow is similar to SDB. We discussed this two years
> ago.
> Aborted commands will be requeued immediately, just like in SDB mode
A SCSI host controller reset must abort all pending commands. Requeuing
SCSI commands during a host controller reset violates the API contract
between the SCSI error handler and SCSI LLDs. I'm not aware of any other
SCSI LLD than the UFS host controller driver that requeues pending
commands upon a host controller reset instead of aborting these.

.eh_host_reset_handler() is expected to reset all logical units and the
host controller. The SCSI architecture manual (SAM) mentions explicitly
that resetting logical units involves aborting all commands.

Thanks,

Bart.