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Date: Sun, 7 Jan 2024 08:02:37 -0800
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Subject: Re: [PATCH v1] ufs: get target SQ entry within critical section
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To: Kiwoong Kim <kwmad.kim@samsung.com>, linux-scsi@vger.kernel.org,
 linux-kernel@vger.kernel.org, alim.akhtar@samsung.com, avri.altman@wdc.com,
 jejb@linux.ibm.com, martin.petersen@oracle.com, beanhuo@micron.com,
 adrian.hunter@intel.com, h10.kim@samsung.com, hy50.seo@samsung.com,
 sh425.lee@samsung.com, kwangwon.min@samsung.com, junwoo80.lee@samsung.com,
 wkon.kim@samsung.com
References: <CGME20240104012454epcas2p36b58220b4c89ee72f1e095b34d329be2@epcas2p3.samsung.com>
 <1704331491-115325-1-git-send-email-kwmad.kim@samsung.com>
From: Bart Van Assche <bvanassche@acm.org>
In-Reply-To: <1704331491-115325-1-git-send-email-kwmad.kim@samsung.com>
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On 1/3/24 17:24, Kiwoong Kim wrote:
> In IO centric scenarios, especially during a period that
> many IO requests are submitted to a same HW queue at the same
> time, it's found that one reqeust overwrote a SQ entry
> that had been already occupied by another request submitted
> in the past. And it eventually led to command timed-out
> because one of two requests were overwritten, which could not
> be completed.
> 
> [   74.995185][  T176] exynos-ufs 17100000.ufs: ufshcd_abort: Device abort task at tag 30
> 
> Signed-off-by: Kiwoong Kim <kwmad.kim@samsung.com>
> ---
>   drivers/ufs/core/ufshcd.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
> index 7bc3fc4..da1a9c0 100644
> --- a/drivers/ufs/core/ufshcd.c
> +++ b/drivers/ufs/core/ufshcd.c
> @@ -2199,9 +2199,10 @@ void ufshcd_send_command(struct ufs_hba *hba, unsigned int task_tag,
>   	if (is_mcq_enabled(hba)) {
>   		int utrd_size = sizeof(struct utp_transfer_req_desc);
>   		struct utp_transfer_req_desc *src = lrbp->utr_descriptor_ptr;
> -		struct utp_transfer_req_desc *dest = hwq->sqe_base_addr + hwq->sq_tail_slot;
> +		struct utp_transfer_req_desc *dest;
>   
>   		spin_lock(&hwq->sq_lock);
> +		dest = hwq->sqe_base_addr + hwq->sq_tail_slot;
>   		memcpy(dest, src, utrd_size);
>   		ufshcd_inc_sq_tail(hwq);
>   		spin_unlock(&hwq->sq_lock);

Is this perhaps a duplicate of patch "scsi: ufs: core: Let the sq_lock 
protect sq_tail_slot access"? See also
https://lore.kernel.org/linux-scsi/1702913550-20631-1-git-send-email-quic_cang@quicinc.com/#t

Thanks,

Bart.