linux-kernel - Re: [PATCH v3] scsi: ufs: core: Fix data race in CPU latency PM QoS request handling

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Message-ID: <9f2cba57-1d4a-4541-b127-5d207e4353c9@oss.qualcomm.com>
Date: Thu, 18 Sep 2025 11:51:12 +0800
From: Zhongqiu Han <zhongqiu.han@....qualcomm.com>
To: Peter Wang (王信友) <peter.wang@...iatek.com>,
        "martin.petersen@...cle.com" <martin.petersen@...cle.com>,
        "James.Bottomley@...senPartnership.com"
 <James.Bottomley@...senPartnership.com>,
        "alim.akhtar@...sung.com" <alim.akhtar@...sung.com>,
        "avri.altman@....com" <avri.altman@....com>,
        "bvanassche@....org" <bvanassche@....org>
Cc: "tanghuan@...o.com" <tanghuan@...o.com>,
        AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>,
        "linux-scsi@...r.kernel.org" <linux-scsi@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "adrian.hunter@...el.com" <adrian.hunter@...el.com>,
        "ebiggers@...nel.org" <ebiggers@...nel.org>,
        "quic_mnaresh@...cinc.com" <quic_mnaresh@...cinc.com>,
        "ziqi.chen@....qualcomm.com" <ziqi.chen@....qualcomm.com>,
        "viro@...iv.linux.org.uk" <viro@...iv.linux.org.uk>,
        "quic_narepall@...cinc.com" <quic_narepall@...cinc.com>,
        "nitin.rawat@....qualcomm.com" <nitin.rawat@....qualcomm.com>,
        "quic_nguyenb@...cinc.com" <quic_nguyenb@...cinc.com>,
        "huobean@...il.com" <huobean@...il.com>,
        "neil.armstrong@...aro.org" <neil.armstrong@...aro.org>,
        "liu.song13@....com.cn" <liu.song13@....com.cn>,
        "can.guo@....qualcomm.com" <can.guo@....qualcomm.com>,
        zhongqiu.han@....qualcomm.com
Subject: Re: [PATCH v3] scsi: ufs: core: Fix data race in CPU latency PM QoS
 request handling

On 9/18/2025 11:16 AM, Peter Wang (王信友) wrote:
> On Wed, 2025-09-17 at 17:41 +0800, Zhongqiu Han wrote:
>> 
>>         ufshcd_init_clk_gating(hba);
>> diff --git a/include/ufs/ufshcd.h b/include/ufs/ufshcd.h
>> index ea0021f067c9..277dda606f4d 100644
>> --- a/include/ufs/ufshcd.h
>> +++ b/include/ufs/ufshcd.h
>> @@ -938,6 +938,7 @@ enum ufshcd_mcq_opr {
>>   * @ufs_rtc_update_work: A work for UFS RTC periodic update
>>   * @pm_qos_req: PM QoS request handle
>>   * @pm_qos_enabled: flag to check if pm qos is enabled
>> + * @pm_qos_mutex: synchronizes PM QoS request and status updates
>>   * @critical_health_count: count of critical health exceptions
>>   * @dev_lvl_exception_count: count of device level exceptions since
>> last reset
>>   * @dev_lvl_exception_id: vendor specific information about the
>> @@ -1110,6 +1111,8 @@ struct ufs_hba {
>>         struct delayed_work ufs_rtc_update_work;
>>         struct pm_qos_request pm_qos_req;
>>         bool pm_qos_enabled;
>> +       /* synchronizes PM QoS request and status updates */
>> 
> 
> Hi Zhongqiu,
> 
> I think this line can be removed to make the code cleaner,
> since you’ve already explained the purpose of each parameter above.
> 
> Thanks.
> Peter
> 
> 
> 
>> +       struct mutex pm_qos_mutex;
>> 
>>         int critical_health_count;
>>         atomic_t dev_lvl_exception_count;
>> --
>> 2.43.0
>> 
> 


Hi Peter,
Thanks a lot for your review~

---
In Patch V1, we got below info from checkpatch.pl strict mode:

include/ufs/ufshcd.h:1140: CHECK:UNCOMMENTED_DEFINITION: struct mutex 
definition without comment
+	struct mutex pm_qos_mutex;


So since V2, the comment was added. I want to strictly follow the
community coding style guidelines. Thank you~

> 
> 
> 
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-- 
Thx and BRs,
Zhongqiu Han