linux-kernel - RE: [PATCH v4] scsi: ufs: Cleanup completed request without interrupt notification

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Message-ID: <1596159018.17247.53.camel@mtkswgap22>
Date:   Fri, 31 Jul 2020 09:30:18 +0800
From:   Stanley Chu <stanley.chu@...iatek.com>
To:     Avri Altman <Avri.Altman@....com>,
        Bart Van Assche <bvanassche@....org>
CC:     "linux-scsi@...r.kernel.org" <linux-scsi@...r.kernel.org>,
        "martin.petersen@...cle.com" <martin.petersen@...cle.com>,
        "alim.akhtar@...sung.com" <alim.akhtar@...sung.com>,
        "jejb@...ux.ibm.com" <jejb@...ux.ibm.com>,
        "bvanassche@....org" <bvanassche@....org>,
        "beanhuo@...ron.com" <beanhuo@...ron.com>,
        "asutoshd@...eaurora.org" <asutoshd@...eaurora.org>,
        "cang@...eaurora.org" <cang@...eaurora.org>,
        "matthias.bgg@...il.com" <matthias.bgg@...il.com>,
        "linux-mediatek@...ts.infradead.org" 
        <linux-mediatek@...ts.infradead.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "kuohong.wang@...iatek.com" <kuohong.wang@...iatek.com>,
        "peter.wang@...iatek.com" <peter.wang@...iatek.com>,
        "chun-hung.wu@...iatek.com" <chun-hung.wu@...iatek.com>,
        "andy.teng@...iatek.com" <andy.teng@...iatek.com>,
        "chaotian.jing@...iatek.com" <chaotian.jing@...iatek.com>,
        "cc.chou@...iatek.com" <cc.chou@...iatek.com>
Subject: RE: [PATCH v4] scsi: ufs: Cleanup completed request without
 interrupt notification

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@...iatek.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