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From: hongwus@codeaurora.org
To: Can Guo <cang@codeaurora.org>
Cc: asutoshd@codeaurora.org, nguyenb@codeaurora.org,
	rnayak@codeaurora.org, sh425.lee@samsung.com,
	linux-scsi@vger.kernel.org, kernel-team@android.com,
	saravanak@google.com, salyzyn@google.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>,
	Stanley Chu <stanley.chu@mediatek.com>,
	Bean Huo <beanhuo@micron.com>,
	Bart Van Assche <bvanassche@acm.org>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v5 2/9] scsi: ufs: Fix imbalanced scsi_block_reqs_cnt caused by ufshcd_hold()
Date: Thu, 23 Jul 2020 11:20:50 +0800	[thread overview]
Message-ID: <307b91fd2d7a59a3e1caa1819e2593e5@codeaurora.org> (raw)
In-Reply-To: <1595471649-25675-3-git-send-email-cang@codeaurora.org>

Hi Can,
On 2020-07-23 10:34, Can Guo wrote:
> The scsi_block_reqs_cnt increased in ufshcd_hold() is supposed to be
> decreased back in ufshcd_ungate_work() in a paired way. However, if
> specific ufshcd_hold/release sequences are met, it is possible that
> scsi_block_reqs_cnt is increased twice but only one ungate work is
> queued. To make sure scsi_block_reqs_cnt is handled by ufshcd_hold() 
> and
> ufshcd_ungate_work() in a paired way, increase it only if queue_work()
> returns true.
> 
> Signed-off-by: Can Guo <cang@codeaurora.org>
> ---
>  drivers/scsi/ufs/ufshcd.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
> index 99bd3e4..2907828 100644
> --- a/drivers/scsi/ufs/ufshcd.c
> +++ b/drivers/scsi/ufs/ufshcd.c
> @@ -1611,12 +1611,12 @@ int ufshcd_hold(struct ufs_hba *hba, bool 
> async)
>  		 */
>  		/* fallthrough */
>  	case CLKS_OFF:
> -		ufshcd_scsi_block_requests(hba);
>  		hba->clk_gating.state = REQ_CLKS_ON;
>  		trace_ufshcd_clk_gating(dev_name(hba->dev),
>  					hba->clk_gating.state);
> -		queue_work(hba->clk_gating.clk_gating_workq,
> -			   &hba->clk_gating.ungate_work);
> +		if (queue_work(hba->clk_gating.clk_gating_workq,
> +			       &hba->clk_gating.ungate_work))
> +			ufshcd_scsi_block_requests(hba);
>  		/*
>  		 * fall through to check if we should wait for this
>  		 * work to be done or not.

Yes, queue_work() may fail for some reasons. We should make sure 
scsi_block_reqs_cnt is balanced. Your change looks good to me since it 
touches scsi_block_reqs_cnt only when the condition is met.

Reviewed-by: Hongwu Su <hongwus@codeaurora.org>


  reply	other threads:[~2020-07-23  3:21 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-23  2:33 [PATCH v5 0/9] Fix up and simplify error recovery mechanism Can Guo
2020-07-23  2:34 ` [PATCH v5 1/9] scsi: ufs: Add checks before setting clk-gating states Can Guo
2020-07-23  2:45   ` hongwus
2020-07-23  2:34 ` [PATCH v5 2/9] scsi: ufs: Fix imbalanced scsi_block_reqs_cnt caused by ufshcd_hold() Can Guo
2020-07-23  3:20   ` hongwus [this message]
2020-07-23  2:34 ` [PATCH v5 3/9] ufs: ufs-qcom: Fix race conditions caused by func ufs_qcom_testbus_config Can Guo
2020-07-23  3:38   ` hongwus
2020-07-23  2:34 ` [PATCH v5 4/9] scsi: ufs-qcom: Fix schedule while atomic error in ufs_qcom_dump_dbg_regs Can Guo
2020-07-23  2:34 ` [PATCH v5 5/9] scsi: ufs: Add some debug infos to ufshcd_print_host_state Can Guo
2020-07-23  2:34 ` [PATCH v5 6/9] scsi: ufs: Fix concurrency of error handler and other error recovery paths Can Guo
2020-07-23  2:34 ` [PATCH v5 7/9] scsi: ufs: Recover hba runtime PM error in error handler Can Guo
2020-07-23  2:34 ` [PATCH v5 8/9] scsi: ufs: Move dumps in IRQ handler to " Can Guo
2020-07-23  2:34 ` [PATCH v5 9/9] scsi: ufs: Fix a racing problem btw error handler and runtime PM ops Can Guo

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