linux-kernel - Re: [PATCH v20 1/2] scsi: ufs: Enable power management for wlun

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Date:   Tue, 20 Apr 2021 07:15:24 +0300
From:   Adrian Hunter <adrian.hunter@...el.com>
To:     "Asutosh Das (asd)" <asutoshd@...eaurora.org>, cang@...eaurora.org,
        martin.petersen@...cle.com, linux-scsi@...r.kernel.org
Cc:     linux-arm-msm@...r.kernel.org,
        Alim Akhtar <alim.akhtar@...sung.com>,
        Avri Altman <avri.altman@....com>,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        Stanley Chu <stanley.chu@...iatek.com>,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Ingo Molnar <mingo@...hat.com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Lee Jones <lee.jones@...aro.org>,
        Bean Huo <beanhuo@...ron.com>,
        Kiwoong Kim <kwmad.kim@...sung.com>,
        Colin Ian King <colin.king@...onical.com>,
        Wei Yongjun <weiyongjun1@...wei.com>,
        Yue Hu <huyue2@...ong.com>,
        Bart van Assche <bvanassche@....org>,
        "Gustavo A. R. Silva" <gustavoars@...nel.org>,
        Dinghao Liu <dinghao.liu@....edu.cn>,
        Jaegeuk Kim <jaegeuk@...nel.org>,
        Satya Tangirala <satyat@...gle.com>,
        open list <linux-kernel@...r.kernel.org>,
        "moderated list:ARM/SAMSUNG S3C, S5P AND EXYNOS ARM ARCHITECTURES" 
        <linux-arm-kernel@...ts.infradead.org>,
        "open list:ARM/SAMSUNG S3C, S5P AND EXYNOS ARM ARCHITECTURES" 
        <linux-samsung-soc@...r.kernel.org>,
        "moderated list:UNIVERSAL FLASH STORAGE HOST CONTROLLER DRIVER..." 
        <linux-mediatek@...ts.infradead.org>
Subject: Re: [PATCH v20 1/2] scsi: ufs: Enable power management for wlun

On 20/04/21 12:53 am, Asutosh Das (asd) wrote:
> On 4/19/2021 11:37 AM, Adrian Hunter wrote:
>> On 16/04/21 10:49 pm, Asutosh Das wrote:
>>>
>>> Co-developed-by: Can Guo <cang@...eaurora.org>
>>> Signed-off-by: Can Guo <cang@...eaurora.org>
>>> Signed-off-by: Asutosh Das <asutoshd@...eaurora.org>
>>> ---
>>
>> I came across 3 issues while testing.  See comments below.
>>
> Hi Adrian
> Thanks for the comments.
>> <SNIP>
>>
>>> @@ -5794,7 +5839,7 @@ static void ufshcd_err_handling_unprepare(struct ufs_hba *hba)
>>>       if (ufshcd_is_clkscaling_supported(hba))
>>>           ufshcd_clk_scaling_suspend(hba, false);
>>>       ufshcd_clear_ua_wluns(hba);
>>
>> ufshcd_clear_ua_wluns() deadlocks trying to clear UFS_UPIU_RPMB_WLUN
>> if sdev_rpmb is suspended and sdev_ufs_device is suspending.
>> e.g. ufshcd_wl_suspend() is waiting on host_sem while ufshcd_err_handler()
>> is running, at which point sdev_rpmb has already suspended.
>>
> Umm, I didn't understand this deadlock.
> When you say, sdev_rpmb is suspended, does it mean runtime_suspended?
> sdev_ufs_device is suspending - this can't be runtime_suspending, while ufshcd_err_handling_unprepare is running.
> 
> If you've a call-stack of this deadlock, please can you share it with me. I'll also try to reproduce this.

Yes it is system suspend. sdev_rpmb has suspended, sdev_ufs_device is waiting on host_sem.
ufshcd_err_handler() holds host_sem. ufshcd_clear_ua_wlun(UFS_UPIU_RPMB_WLUN) gets stuck.
I will get some call-stacks.

> 
> I'll address the other comments in the next version.
> 
> 
> Thank you!
> 
>>> -    pm_runtime_put(hba->dev);
>>> +    ufshcd_rpm_put(hba);
>>>   }
>>
>> <SNIP>
>>
>>> +void ufshcd_resume_complete(struct device *dev)
>>> +{
>