linux-kernel - Re: [PATCH 2/2] scsi: ufs: Protect PM ops and err

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Date:   Mon, 11 Jan 2021 09:30:24 +0800
From:   Can Guo <cang@...eaurora.org>
To:     Bean Huo <huobean@...il.com>
Cc:     asutoshd@...eaurora.org, nguyenb@...eaurora.org,
        hongwus@...eaurora.org, ziqichen@...eaurora.org,
        rnayak@...eaurora.org, linux-scsi@...r.kernel.org,
        kernel-team@...roid.com, saravanak@...gle.com, salyzyn@...gle.com,
        Alim Akhtar <alim.akhtar@...sung.com>,
        Avri Altman <avri.altman@....com>,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        Stanley Chu <stanley.chu@...iatek.com>,
        Bean Huo <beanhuo@...ron.com>,
        Nitin Rawat <nitirawa@...eaurora.org>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Bart Van Assche <bvanassche@....org>,
        Satya Tangirala <satyat@...gle.com>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/2] scsi: ufs: Protect PM ops and err_handler from user
 access through sysfs

On 2021-01-11 00:18, Bean Huo wrote:
> On Sat, 2021-01-02 at 05:59 -0800, Can Guo wrote:
>> + * @shutting_down: flag to check if shutdown has been invoked
>> + * @host_sem: semaphore used to serialize concurrent contexts
>>   * @eh_wq: Workqueue that eh_work works on
>>   * @eh_work: Worker to handle UFS errors that require s/w attention
>>   * @eeh_work: Worker to handle exception events
>> @@ -751,7 +753,8 @@ struct ufs_hba {
>>         u32 intr_mask;
>>         u16 ee_ctrl_mask;
>>         bool is_powered;
>> -       struct semaphore eh_sem;
>> +       bool shutting_down;
>> +       struct semaphore host_sem;
>> 
>>         /* Work Queues */
>>         struct workqueue_struct *eh_wq;
>> @@ -875,6 +878,11 @@ static inline bool ufshcd_is_wb_allowed(struct
>> ufs_hba *hba)
>>         return hba->caps & UFSHCD_CAP_WB_EN;
>>  }
>> 
>> +static inline bool ufshcd_is_sysfs_allowed(struct ufs_hba *hba)
>> +{
>> +       return !hba->shutting_down;
>> +}
>> +
> 
> 
> Can,
> 
> Instead adding new shutting_down flag, can we use availible variable
> system_state?
> 
> Thanks,
> Bean

Hi Bean,

I prefer the flag shutting_down, it tells us whether ufshcd_shutdown()
has been invoked or not. It comes handy when debug some system crash
issues caused by UFS during reboot/shutdown tests. system_state is too
wide in this case.

Thanks,
Can Guo.