Re: [RFC PATCH v2] md: remove legacy 1s delay in md_notify_reboot

[Pasha Tatashin]

On Sat, Nov 29, 2025 at 8:58 PM Yu Kuai <yukuai@xxxxxxxxx> wrote:
>
> 在 2025/11/22 3:14, Tarun Sahu 写道:
>
> > During system shutdown, the md driver registered notifier function
> > (md_notify_reboot) currently imposes a hardcoded one-second delay.
> >
> > This delay was introduced approximately 23 years ago and was likely
> > necessary for the hardware generation of that time. Proposing this
> > patch to make sure there are no known devices that need this delay.
> >
> > Signed-off-by: Tarun Sahu <tarunsahu@xxxxxxxxxx>
> > ---
> > v2:
> >       Added linux-scsi mailing list
> >
> >   drivers/md/md.c | 11 -----------
> >   1 file changed, 11 deletions(-)
> >
> > diff --git a/drivers/md/md.c b/drivers/md/md.c
> > index b086cbf24086..66c4d66b4b86 100644
> > --- a/drivers/md/md.c
> > +++ b/drivers/md/md.c
> > @@ -9704,7 +9704,6 @@ static int md_notify_reboot(struct notifier_block *this,
> >                           unsigned long code, void *x)
> >   {
> >       struct mddev *mddev;
> > -     int need_delay = 0;
> >
> >       spin_lock(&all_mddevs_lock);
> >       list_for_each_entry(mddev, &all_mddevs, all_mddevs) {
> > @@ -9718,21 +9717,11 @@ static int md_notify_reboot(struct notifier_block *this,
> >                               mddev->safemode = 2;
> >                       mddev_unlock(mddev);
> >               }
> > -             need_delay = 1;
> >               spin_lock(&all_mddevs_lock);
> >               mddev_put_locked(mddev);
> >       }
> >       spin_unlock(&all_mddevs_lock);
> >
> > -     /*
> > -      * certain more exotic SCSI devices are known to be
> > -      * volatile wrt too early system reboots. While the
> > -      * right place to handle this issue is the given
> > -      * driver, we do want to have a safe RAID driver ...
> > -      */
> > -     if (need_delay)
> > -             msleep(1000);
> > -
> >       return NOTIFY_DONE;
> >   }
> >
>
> Applied to md-6.19

Awesome, thanks.

Pasha