On Wed, Jul 22 2020 at 2:46pm -0400,
Mikulas Patocka <mpatocka@xxxxxxxxxx> wrote:
> Hi Mike
>
> Please submit this to Linus and to RHEL-8.
>
> Mikulas
>
>
>
> From: Mikulas Patocka <mpatocka@xxxxxxxxxx>
>
> The patch adc0daad366b62ca1bce3e2958a40b0b71a8b8b3 broke recalculation on
> dm-integrity. The patch replaces a private variable "suspending" with a
> call to "dm_suspended".
>
> The problem is that dm_suspended returns true not only during suspend, but
> also during resume. This race condition could occur:
> 1. dm_integrity_resume calls queue_work(ic->recalc_wq, &ic->recalc_work)
> 2. integrity_recalc (&ic->recalc_work) preempts the current thread
> 3. integrity_recalc calls if (unlikely(dm_suspended(ic->ti))) goto unlock_ret;
> 4. integrity_recalc exits and no recalculating is done.
>
> In order to fix this race condition, we stop using dm_suspended and start
> using the variable "suspending" (that is only set during suspend, not
> during resume).
>
> Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx>
> Fixes: adc0daad366b ("dm: report suspended device during destroy")
> Cc: stable@xxxxxxxxxxxxxxx # v4.18+
OK, but why not add a dm_suspending() to DM core? Could be other
future targets would like this same info right? I don't see harm in
elevating it.
Mike
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