[PATCH v4] scsi: ufs: Cleanup completed request without interrupt notification

[Stanley Chu]

Hi Bart,

On Mon, 2020-07-27 at 11:18 +0000, Avri Altman wrote:
> Looks good to me.
> But better wait and see if Bart have any further reservations.
> 

Would you have any further suggestions?

Thanks a lot,
Stanley Chu

> Thanks,
> Avri 
> > 
> > If somehow no interrupt notification is raised for a completed request
> > and its doorbell bit is cleared by host, UFS driver needs to cleanup
> > its outstanding bit in ufshcd_abort(). Otherwise, system may behave
> > abnormally by below flow:
> > 
> > After ufshcd_abort() returns, this request will be requeued by SCSI
> > layer with its outstanding bit set. Any future completed request
> > will trigger ufshcd_transfer_req_compl() to handle all "completed
> > outstanding bits". In this time, the "abnormal outstanding bit"
> > will be detected and the "requeued request" will be chosen to execute
> > request post-processing flow. This is wrong because this request is
> > still "alive".
> > 
> > Signed-off-by: Stanley Chu <stanley.chu at mediatek.com>
> > ---
> >  drivers/scsi/ufs/ufshcd.c | 3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
> > index 577cc0d7487f..9d180da77488 100644
> > --- a/drivers/scsi/ufs/ufshcd.c
> > +++ b/drivers/scsi/ufs/ufshcd.c
> > @@ -6493,7 +6493,7 @@ static int ufshcd_abort(struct scsi_cmnd *cmd)
> >                         /* command completed already */
> >                         dev_err(hba->dev, "%s: cmd at tag %d successfully cleared from
> > DB.\n",
> >                                 __func__, tag);
> > -                       goto out;
> > +                       goto cleanup;
> >                 } else {
> >                         dev_err(hba->dev,
> >                                 "%s: no response from device. tag = %d, err %d\n",
> > @@ -6527,6 +6527,7 @@ static int ufshcd_abort(struct scsi_cmnd *cmd)
> >                 goto out;
> >         }
> > 
> > +cleanup:
> >         scsi_dma_unmap(cmd);
> > 
> >         spin_lock_irqsave(host->host_lock, flags);
> > --
> > 2.18.0