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Message-ID: <61ff835b-bd00-8cf3-6e4a-30c82cf9e7b1@acm.org>
Date:   Thu, 1 Jun 2023 07:08:47 -0700
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Subject: Re: [PATCH v2] scsi: ufs: core: Fix ufshcd_inc_sq_tail function bug
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To:     Zhang Hui <masonzhang.xiaomi@gmail.com>,
        Alim Akhtar <alim.akhtar@samsung.com>,
        Avri Altman <avri.altman@wdc.com>,
        "James E . J . Bottomley" <jejb@linux.ibm.com>,
        "Martin K . Petersen" <martin.petersen@oracle.com>
Cc:     Can Guo <quic_cang@quicinc.com>,
        Manivannan Sadhasivam <mani@kernel.org>,
        Asutosh Das <quic_asutoshd@quicinc.com>,
        Arthur Simchaev <Arthur.Simchaev@wdc.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>,
        zhanghui <zhanghui31@xiaomi.com>, Bean Huo <beanhuo@micron.com>,
        peng.zhou@mediatek.com, yudongbin@xiaomi.com,
        linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org
References: <20230601124613.1446-1-zhanghui31@xiaomi.com>
From:   Bart Van Assche <bvanassche@acm.org>
In-Reply-To: <20230601124613.1446-1-zhanghui31@xiaomi.com>
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On 6/1/23 05:46, Zhang Hui wrote:
> From: zhanghui <zhanghui31@xiaomi.com>
> 
> When qdepth is not power of 2, not every bit of the mask is 1, so
> sq_tail_slot some bits will be cleared unexpected.
> 
> Signed-off-by: zhanghui <zhanghui31@xiaomi.com>
> ---
>   drivers/ufs/core/ufshcd-priv.h | 5 +++--
>   1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/ufs/core/ufshcd-priv.h b/drivers/ufs/core/ufshcd-priv.h
> index d53b93c21a0c..319fba31c1f5 100644
> --- a/drivers/ufs/core/ufshcd-priv.h
> +++ b/drivers/ufs/core/ufshcd-priv.h
> @@ -366,10 +366,11 @@ static inline bool ufs_is_valid_unit_desc_lun(struct ufs_dev_info *dev_info, u8
>   static inline void ufshcd_inc_sq_tail(struct ufs_hw_queue *q)
>   	__must_hold(&q->sq_lock)
>   {
> -	u32 mask = q->max_entries - 1;
>   	u32 val;
>   
> -	q->sq_tail_slot = (q->sq_tail_slot + 1) & mask;
> +	q->sq_tail_slot++;
> +	if (q->sq_tail_slot == q->max_entries)
> +		q->sq_tail_slot = 0;
>   	val = q->sq_tail_slot * sizeof(struct utp_transfer_req_desc);
>   	writel(val, q->mcq_sq_tail);
>   }

Reviewed-by: Bart Van Assche <bvanassche@acm.org>