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Subject: Re: [PATCH v20 1/2] scsi: ufs: Enable power management for wlun
To:     "Asutosh Das (asd)" <asutoshd@codeaurora.org>, cang@codeaurora.org,
        martin.petersen@oracle.com, linux-scsi@vger.kernel.org
Cc:     linux-arm-msm@vger.kernel.org,
        Alim Akhtar <alim.akhtar@samsung.com>,
        Avri Altman <avri.altman@wdc.com>,
        "James E.J. Bottomley" <jejb@linux.ibm.com>,
        Krzysztof Kozlowski <krzk@kernel.org>,
        Stanley Chu <stanley.chu@mediatek.com>,
        Andy Gross <agross@kernel.org>,
        Bjorn Andersson <bjorn.andersson@linaro.org>,
        Steven Rostedt <rostedt@goodmis.org>,
        Ingo Molnar <mingo@redhat.com>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        Lee Jones <lee.jones@linaro.org>,
        Bean Huo <beanhuo@micron.com>,
        Kiwoong Kim <kwmad.kim@samsung.com>,
        Colin Ian King <colin.king@canonical.com>,
        Wei Yongjun <weiyongjun1@huawei.com>,
        Yue Hu <huyue2@yulong.com>,
        Bart van Assche <bvanassche@acm.org>,
        "Gustavo A. R. Silva" <gustavoars@kernel.org>,
        Dinghao Liu <dinghao.liu@zju.edu.cn>,
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        open list <linux-kernel@vger.kernel.org>,
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References: <cover.1618600985.git.asutoshd@codeaurora.org>
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 <fdadd467-b613-d800-18c5-be064396fd10@intel.com>
 <07e3ea07-e1c3-7b8c-e398-8b008f873e6d@codeaurora.org>
From:   Adrian Hunter <adrian.hunter@intel.com>
Organization: Intel Finland Oy, Registered Address: PL 281, 00181 Helsinki,
 Business Identity Code: 0357606 - 4, Domiciled in Helsinki
Message-ID: <90809796-1c32-3709-13d3-65e4d5c387cc@intel.com>
Date:   Tue, 20 Apr 2021 07:15:24 +0300
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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@codeaurora.org>
>>> Signed-off-by: Can Guo <cang@codeaurora.org>
>>> Signed-off-by: Asutosh Das <asutoshd@codeaurora.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)
>>> +{
>