linux-kernel - RE: [PATCH v7 5/8] scsi: ufs: Fix ufshcd_hold() caused scheduling while atomic

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Message-ID: <MN2PR04MB699118580A00AF07917CDDE1FC190@MN2PR04MB6991.namprd04.prod.outlook.com>
Date:   Mon, 10 Feb 2020 08:23:29 +0000
From:   Avri Altman <Avri.Altman@....com>
To:     Can Guo <cang@...eaurora.org>
CC:     "asutoshd@...eaurora.org" <asutoshd@...eaurora.org>,
        "nguyenb@...eaurora.org" <nguyenb@...eaurora.org>,
        "hongwus@...eaurora.org" <hongwus@...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>,
        Alim Akhtar <alim.akhtar@...sung.com>,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Bean Huo <beanhuo@...ron.com>,
        Stanley Chu <stanley.chu@...iatek.com>,
        Bart Van Assche <bvanassche@....org>,
        Venkat Gopalakrishnan <venkatg@...eaurora.org>,
        Tomas Winkler <tomas.winkler@...el.com>,
        open list <linux-kernel@...r.kernel.org>,
        "moderated list:ARM/Mediatek SoC support" 
        <linux-arm-kernel@...ts.infradead.org>,
        "moderated list:ARM/Mediatek SoC support" 
        <linux-mediatek@...ts.infradead.org>
Subject: RE: [PATCH v7 5/8] scsi: ufs: Fix ufshcd_hold() caused scheduling
 while atomic

> >> Fixes: f2a785ac2312 (scsi: ufshcd: Fix race between clk scaling and
> >> ungate work)
> >
> > Sorry, missed this one, if another version is needed, I will add this
> > line.
fair enough.

> >
> >>>
> >>> Signed-off-by: Can Guo <cang@...eaurora.org>
> >>> Reviewed-by: Hongwu Su <hongwus@...eaurora.org>
> >>> Reviewed-by: Asutosh Das <asutoshd@...eaurora.org>
> >>> Reviewed-by: Bean Huo <beanhuo@...ron.com>
> >>> Reviewed-by: Stanley Chu <stanley.chu@...iatek.com>
> >>> ---
> >>>  drivers/scsi/ufs/ufshcd.c | 5 +++++
> >>>  1 file changed, 5 insertions(+)
> >>>
> >>> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
> >>> index bbc2607..e8f7f9d 100644
> >>> --- a/drivers/scsi/ufs/ufshcd.c
> >>> +++ b/drivers/scsi/ufs/ufshcd.c
> >>> @@ -1518,6 +1518,11 @@ int ufshcd_hold(struct ufs_hba *hba, bool
> >>> async)
> >>>                  */
> >>>                 if (ufshcd_can_hibern8_during_gating(hba) &&
> >>>                     ufshcd_is_link_hibern8(hba)) {
> >>> +                       if (async) {
> >>> +                               rc = -EAGAIN;
> >>> +                               hba->clk_gating.active_reqs--;
> >>> +                               break;
> >>> +                       }
> >>>                         spin_unlock_irqrestore(hba->host->host_lock,
> >>> flags);
> >>>                         flush_work(&hba->clk_gating.ungate_work);
> >>>                         spin_lock_irqsave(hba->host->host_lock,
> >>> flags);
> >> Since now the above code is shared in all cases,
> >> Maybe find a more economical way to pack it?
> >>
> >> Thanks,
> >> Avri
> >>
> >>
> >
> > There are only 2 of this same code pieces in ufshcd_hold() and located
> > in different cases, meanwhile there can be fall through, I don't see
> > a good way to pack it, can you suggest if you have any ideas?
> >
> 
> Now, with this patch, there are 2 same code snippets located in CLKS_ON
> and REQ_CLKS_ON. If we somehow pack them, say bring in a inline func to
> pack them, we would have to tear it down later if we have to fix
> something for only one specific case by adding lines into the snippet.
> And actually this is the truth, we do have some fixes for CLKS_ON's case
> but not yet uploaded, so let's leave it as it is for now.
OK.

Thanks,
Avri