linux-kernel - Re: [PATCH] scsi: ufs: fix livelock of ufshcd_clear_ua

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Message-ID: <153e563a381c580f76447a12df9f4138@codeaurora.org>
Date:   Mon, 21 Dec 2020 12:25:02 +0800
From:   Can Guo <cang@...eaurora.org>
To:     Jaegeuk Kim <jaegeuk@...nel.org>
Cc:     linux-kernel@...r.kernel.org, linux-scsi@...r.kernel.org,
        kernel-team@...roid.com, alim.akhtar@...sung.com,
        avri.altman@....com, bvanassche@....org,
        martin.petersen@...cle.com, stanley.chu@...iatek.com
Subject: Re: [PATCH] scsi: ufs: fix livelock of ufshcd_clear_ua_wluns

On 2020-12-18 11:31, Jaegeuk Kim wrote:
> When gate_work/ungate_work gets an error during hibern8_enter or exit,
>  ufshcd_err_handler()
>    ufshcd_scsi_block_requests()
>    ufshcd_reset_and_restore()
>      ufshcd_clear_ua_wluns() -> stuck
>    ufshcd_scsi_unblock_requests()
> 
> In order to avoid it, ufshcd_clear_ua_wluns() can be called per 
> recovery flows
> such as suspend/resume, link_recovery, and error_handler.
> 
> Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org>
> ---
>  drivers/scsi/ufs/ufshcd.c | 14 +++++++++-----
>  1 file changed, 9 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
> index e221add25a7e..e711def829cd 100644
> --- a/drivers/scsi/ufs/ufshcd.c
> +++ b/drivers/scsi/ufs/ufshcd.c
> @@ -3963,6 +3963,8 @@ int ufshcd_link_recovery(struct ufs_hba *hba)
>  	if (ret)
>  		dev_err(hba->dev, "%s: link recovery failed, err %d",
>  			__func__, ret);
> +	else
> +		ufshcd_clear_ua_wluns(hba);
> 
>  	return ret;
>  }
> @@ -5968,6 +5970,8 @@ static void ufshcd_err_handler(struct work_struct 
> *work)
>  	ufshcd_scsi_unblock_requests(hba);
>  	ufshcd_err_handling_unprepare(hba);
>  	up(&hba->eh_sem);
> +

Maybe add a check like if (!err && needs_reset) as error handler
also handles non-fatal errors which do not require a full reset
and restore?

> +	ufshcd_clear_ua_wluns(hba);
>  }
> 
>  /**
> @@ -6908,14 +6912,11 @@ static int
> ufshcd_host_reset_and_restore(struct ufs_hba *hba)
>  	ufshcd_set_clk_freq(hba, true);
> 
>  	err = ufshcd_hba_enable(hba);
> -	if (err)
> -		goto out;
> 
>  	/* Establish the link again and restore the device */
> -	err = ufshcd_probe_hba(hba, false);
>  	if (!err)
> -		ufshcd_clear_ua_wluns(hba);
> -out:
> +		err = ufshcd_probe_hba(hba, false);
> +
>  	if (err)
>  		dev_err(hba->dev, "%s: Host init failed %d\n", __func__, err);
>  	ufshcd_update_evt_hist(hba, UFS_EVT_HOST_RESET, (u32)err);
> @@ -8745,6 +8746,7 @@ static int ufshcd_suspend(struct ufs_hba *hba,
> enum ufs_pm_op pm_op)
>  		ufshcd_resume_clkscaling(hba);
>  	hba->clk_gating.is_suspended = false;
>  	hba->dev_info.b_rpm_dev_flush_capable = false;
> +	ufshcd_clear_ua_wluns(hba);
>  	ufshcd_release(hba);
>  out:
>  	if (hba->dev_info.b_rpm_dev_flush_capable) {
> @@ -8855,6 +8857,8 @@ static int ufshcd_resume(struct ufs_hba *hba,
> enum ufs_pm_op pm_op)
>  		cancel_delayed_work(&hba->rpm_dev_flush_recheck_work);
>  	}
> 
> +	ufshcd_clear_ua_wluns(hba);
> +
>  	/* Schedule clock gating in case of no access to UFS device yet */
>  	ufshcd_release(hba);