Re: [PATCH v3 2/2] scsi: ufs: core: Decouple CQ sweep from request iterator in MCQ

[Peter Wang <peter.wang@mediatek.com>]

On Mon, 2026-09-28 at 11:58 +0800, Stanley Jhu wrote:
> In MCQ mode, ufshcd_mcq_compl_pending_transfer() uses
> blk_mq_tagset_busy_iter() to iterate over busy requests during error
> recovery and host reset. However, both iterator callbacks perform
> whole-queue operations redundantly for each visited request:
> 
> - force_compl == true: ufshcd_mcq_force_compl_one() calls
>   ufshcd_mcq_compl_all_cqes_lock() on every busy request, sweeping
> the
>   entire completion ring (hwq->max_entries slots) once per active
>   request under spin_lock_irqsave even though the first sweep already
>   cleared all completion entries.
> - force_compl == false: ufshcd_mcq_compl_one() acquires cq_lock and
>   polls CQTPy over MMIO via ufshcd_mcq_poll_cqe_lock() for every busy
>   request without doing any per-request work.
> 
> Sweep or poll each hardware queue (hba->uhq[i]) once at the start of
> ufshcd_mcq_compl_pending_transfer(). When force_compl is true, run
> blk_mq_tagset_busy_iter() afterward to complete residual in-flight
> requests with DID_REQUEUE, and remove the now-unused
> ufshcd_mcq_compl_one() callback.
> 
> Fixes: ab248643d3d6 ("scsi: ufs: core: Add error handling for MCQ
> mode")
> Cc: stable@vger.kernel.org
> Reviewed-by: Bart Van Assche <bvanassche@acm.org>
> Signed-off-by: Stanley Jhu <stanleyjhu@google.com>

Reviewed-by: Peter Wang <peter.wang@mediatek.com>