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Subject: Re: [PATCH v4 10/10] scsi: ufs: Apply more limitations to user access
To:     Can Guo <cang@codeaurora.org>
Cc:     asutoshd@codeaurora.org, nguyenb@codeaurora.org,
        hongwus@codeaurora.org, ziqichen@codeaurora.org,
        linux-scsi@vger.kernel.org, kernel-team@android.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>,
        Adrian Hunter <adrian.hunter@intel.com>,
        Bean Huo <beanhuo@micron.com>,
        Stanley Chu <stanley.chu@mediatek.com>,
        Keoseong Park <keosung.park@samsung.com>,
        "Gustavo A. R. Silva" <gustavoars@kernel.org>,
        Jaegeuk Kim <jaegeuk@kernel.org>,
        Kiwoong Kim <kwmad.kim@samsung.com>,
        Satya Tangirala <satyat@google.com>,
        open list <linux-kernel@vger.kernel.org>
References: <1624433711-9339-1-git-send-email-cang@codeaurora.org>
 <1624433711-9339-12-git-send-email-cang@codeaurora.org>
 <89a3c8bf-bbfc-4a2a-73f0-a0db956fbf0e@acm.org>
 <d9db00ef6dd4b28d0ba2019dcf026479@codeaurora.org>
From:   Bart Van Assche <bvanassche@acm.org>
Message-ID: <e803db99-947c-f217-e0c8-091241014086@acm.org>
Date:   Thu, 24 Jun 2021 15:25:44 -0700
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On 6/23/21 7:23 PM, Can Guo wrote:
> On 2021-06-24 05:51, Bart Van Assche wrote:
>> On 6/23/21 12:35 AM, Can Guo wrote:
>> - During system suspend, user space software is paused before the device
>>   driver freeze callbacks are invoked. Hence, the hba->is_sys_suspended
>>   check can be left out.
> 
> is_sys_suspended indicates that system resume failed (power/clk is OFF).
> 
>> - If a LUN is runtime suspended, it should be resumed if accessed from
>>   user space instead of failing user space accesses. In other words, the
>>   hba->is_wlu_sys_suspended check seems inappropriate to me.
> 
> hba->is_wlu_sys_suspended indicates that wl system resume failed, device
> is not operational.

Hi Can,

Thanks for the clarification. How about converting the above two answers
into comments inside ufshcd_is_user_access_allowed()?

Should ufshcd_is_user_access_allowed() perhaps be called after
ufshcd_rpm_get_sync() instead of before to prevent that the value of
hba->is_sys_suspended or hba->is_wlu_sys_suspended changes after having
been checked and before the UFS device is accessed?

Thanks,

Bart.