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

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Date:   Tue, 12 Jan 2021 08:20:11 +0000
From:   Avri Altman <Avri.Altman@....com>
To:     Bean Huo <huobean@...il.com>, Can Guo <cang@...eaurora.org>,
        "asutoshd@...eaurora.org" <asutoshd@...eaurora.org>,
        "nguyenb@...eaurora.org" <nguyenb@...eaurora.org>,
        "hongwus@...eaurora.org" <hongwus@...eaurora.org>,
        "ziqichen@...eaurora.org" <ziqichen@...eaurora.org>,
        "rnayak@...eaurora.org" <rnayak@...eaurora.org>,
        "linux-scsi@...r.kernel.org" <linux-scsi@...r.kernel.org>,
        "kernel-team@...roid.com" <kernel-team@...roid.com>,
        "saravanak@...gle.com" <saravanak@...gle.com>,
        "salyzyn@...gle.com" <salyzyn@...gle.com>
CC:     Alim Akhtar <alim.akhtar@...sung.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 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?
> 
Like Can, I am too, don't think that using system state here, e.g. UFS_SHUTDOWN_PM suffices.
The use of the new flag, jointly with the semaphore, provides a tighter control.

Acked-by: Avri Altman <avri.altman@....com>