linux-kernel - Re: [PATCH] mmc: inline the first mmc_scan() on mmc_start

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Message-ID: <ZIs3FQMiU75EhT6S@snowbird>
Date:   Thu, 15 Jun 2023 09:06:45 -0700
From:   Dennis Zhou <dennis@...nel.org>
To:     Ulf Hansson <ulf.hansson@...aro.org>
Cc:     linux-mmc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mmc: inline the first mmc_scan() on mmc_start_host()

On Tue, Jun 13, 2023 at 04:25:11PM +0200, Ulf Hansson wrote:
> On Wed, 29 Mar 2023 at 22:21, Dennis Zhou <dennis@...nel.org> wrote:
> >
> > When using dm-verity with a data partition on an emmc device, dm-verity
> > races with the discovery of attached emmc devices. This is because mmc's
> > probing code sets up the host data structure then a work item is
> > scheduled to do discovery afterwards. To prevent this race on init,
> > let's inline the first call to detection, __mm_scan(), and let
> > subsequent detect calls be handled via the workqueue.
> >
> > Signed-off-by: Dennis Zhou <dennis@...nel.org>
> 
> Along with the patch for the mmci driver, this one applied too, for
> next, thanks!
> 

Thank you Ulf! I'm good with this just being applied to for-next.

Thanks,
Dennis

> Note also that I took the liberty to clarify the commit message a bit.
> 
> Moreover, if we want this to be applied for stable kernels, we need to
> manage that separately, as then the mmci patch is needed too. Please
> ping if you need some pointers in regards to this.
> 
> Kind regards
> Uffe
> 
> > ---
> >  drivers/mmc/core/core.c | 15 +++++++++++----
> >  1 file changed, 11 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
> > index 368f10405e13..c0fdc438c882 100644
> > --- a/drivers/mmc/core/core.c
> > +++ b/drivers/mmc/core/core.c
> > @@ -2185,10 +2185,8 @@ int mmc_card_alternative_gpt_sector(struct mmc_card *card, sector_t *gpt_sector)
> >  }
> >  EXPORT_SYMBOL(mmc_card_alternative_gpt_sector);
> >
> > -void mmc_rescan(struct work_struct *work)
> > +void __mmc_rescan(struct mmc_host *host)
> >  {
> > -       struct mmc_host *host =
> > -               container_of(work, struct mmc_host, detect.work);
> >         int i;
> >
> >         if (host->rescan_disable)
> > @@ -2249,6 +2247,14 @@ void mmc_rescan(struct work_struct *work)
> >                 mmc_schedule_delayed_work(&host->detect, HZ);
> >  }
> >
> > +void mmc_rescan(struct work_struct *work)
> > +{
> > +       struct mmc_host *host =
> > +               container_of(work, struct mmc_host, detect.work);
> > +
> > +       __mmc_rescan(host);
> > +}
> > +
> >  void mmc_start_host(struct mmc_host *host)
> >  {
> >         host->f_init = max(min(freqs[0], host->f_max), host->f_min);
> > @@ -2261,7 +2267,8 @@ void mmc_start_host(struct mmc_host *host)
> >         }
> >
> >         mmc_gpiod_request_cd_irq(host);
> > -       _mmc_detect_change(host, 0, false);
> > +       host->detect_change = 1;
> > +       __mmc_rescan(host);
> >  }
> >
> >  void __mmc_stop_host(struct mmc_host *host)
> > --
> > 2.40.0
> >