linux-kernel - RE: [PATCH V4 2/2] scsi: ufshcd: Fix device links when BOOT WLUN fails to probe

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Message-ID: <DM6PR04MB657536B3CDF0487E07894A16FCEF9@DM6PR04MB6575.namprd04.prod.outlook.com>
Date:   Mon, 2 Aug 2021 07:03:12 +0000
From:   Avri Altman <Avri.Altman@....com>
To:     Adrian Hunter <adrian.hunter@...el.com>,
        "Rafael J . Wysocki" <rafael@...nel.org>
CC:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Saravana Kannan <saravanak@...gle.com>,
        "Martin K . Petersen" <martin.petersen@...cle.com>,
        "James E . J . Bottomley" <jejb@...ux.ibm.com>,
        "linux-scsi@...r.kernel.org" <linux-scsi@...r.kernel.org>,
        Bean Huo <huobean@...il.com>, Can Guo <cang@...eaurora.org>,
        Asutosh Das <asutoshd@...eaurora.org>,
        Bart Van Assche <bvanassche@....org>,
        "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH V4 2/2] scsi: ufshcd: Fix device links when BOOT WLUN
 fails to probe

 
> On 17/07/21 9:02 pm, Avri Altman wrote:
> >> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
> >> index 708b3b62fc4d..9864a8ee0263 100644
> >> --- a/drivers/scsi/ufs/ufshcd.c
> >> +++ b/drivers/scsi/ufs/ufshcd.c
> >> @@ -5020,15 +5020,34 @@ static int ufshcd_slave_configure(struct
> >> scsi_device
> >> *sdev)
> >>  static void ufshcd_slave_destroy(struct scsi_device *sdev)  {
> >>         struct ufs_hba *hba;
> >> +       unsigned long flags;
> >>
> >>         hba = shost_priv(sdev->host);
> >>         /* Drop the reference as it won't be needed anymore */
> >>         if (ufshcd_scsi_to_upiu_lun(sdev->lun) ==
> UFS_UPIU_UFS_DEVICE_WLUN) {
> >> -               unsigned long flags;
> >> -
> >>                 spin_lock_irqsave(hba->host->host_lock, flags);
> >>                 hba->sdev_ufs_device = NULL;
> >>                 spin_unlock_irqrestore(hba->host->host_lock, flags);
> >> +       } else if (hba->sdev_ufs_device) {
> >> +               struct device *supplier = NULL;
> >> +
> >> +               /* Ensure UFS Device WLUN exists and does not disappear */
> >> +               spin_lock_irqsave(hba->host->host_lock, flags);
> >> +               if (hba->sdev_ufs_device) {
> > Was just checked in the outer clause?
> 
> Yes, but need to re-check with the spinlock locked.
OK.
Looks good to me.
Thanks,
Avri

> 
> >
> > Thanks,
> > Avri
> >
> >> +                       supplier = &hba->sdev_ufs_device->sdev_gendev;
> >> +                       get_device(supplier);
> >> +               }
> >> +               spin_unlock_irqrestore(hba->host->host_lock, flags);
> >> +
> >> +               if (supplier) {
> >> +                       /*
> >> +                        * If a LUN fails to probe (e.g. absent BOOT WLUN), the
> >> +                        * device will not have been registered but can still
> >> +                        * have a device link holding a reference to the device.
> >> +                        */
> >> +                       device_link_remove(&sdev->sdev_gendev, supplier);
> >> +                       put_device(supplier);
> >> +               }
> >>         }
> >>  }
> >>
> >> --
> >> 2.17.1
> >