linux-kernel - Re: [PATCH v3 1/2] scsi: ufs: fix livelock of ufshcd_clear_ua

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Date:   Thu, 07 Jan 2021 15:09:21 +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 v3 1/2] scsi: ufs: fix livelock of ufshcd_clear_ua_wluns

On 2021-01-07 14:57, Jaegeuk Kim wrote:
> On 01/07, Can Guo wrote:
>> On 2021-01-07 05:41, 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.
>> >
>> > Fixes: 1918651f2d7e ("scsi: ufs: Clear UAC for RPMB after ufshcd
>> > resets")
>> > Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org>
>> > ---
>> >  drivers/scsi/ufs/ufshcd.c | 15 ++++++++++-----
>> >  1 file changed, 10 insertions(+), 5 deletions(-)
>> >
>> > diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
>> > index bedb822a40a3..1678cec08b51 100644
>> > --- a/drivers/scsi/ufs/ufshcd.c
>> > +++ b/drivers/scsi/ufs/ufshcd.c
>> > @@ -3996,6 +3996,8 @@ 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);
>> 
>> Can we put it right after ufshcd_scsi_add_wlus() in ufshcd_add_lus()?
> 
> May I ask the reason? We'll call it after ufshcd_add_lus() later tho.
> 

I think the code will be more readable - we do all the LU related
stuffs in one func, just nit-picking though. I found this because
I am planning to move the devfreq init codes out of ufshcd_add_lus()
due to it is inappropriate to init devfreq in there by its naming,
but it might be a good place for ufshcd_clear_ua_wluns().

Thanks,
Can Guo.

>> 
>> Thanks,
>> Can Guo.
>> 
>> >
>> >  	return ret;
>> >  }
>> > @@ -6003,6 +6005,9 @@ static void ufshcd_err_handler(struct work_struct
>> > *work)
>> >  	ufshcd_scsi_unblock_requests(hba);
>> >  	ufshcd_err_handling_unprepare(hba);
>> >  	up(&hba->eh_sem);
>> > +
>> > +	if (!err && needs_reset)
>> > +		ufshcd_clear_ua_wluns(hba);
>> >  }
>> >
>> >  /**
>> > @@ -6940,14 +6945,11 @@ 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);
>> > @@ -8777,6 +8779,7 @@ 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) {
>> > @@ -8887,6 +8890,8 @@ 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);