linux-kernel - Re: [PATCH 4.19 84/86] dm integrity: fix integrity recalculation that is improperly skipped

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Message-ID: <20200727205635.t23z72lkdofoewi3@duo.ucw.cz>
Date:   Mon, 27 Jul 2020 22:56:35 +0200
From:   Pavel Machek <pavel@...x.de>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        Mike Snitzer <snitzer@...hat.com>
Subject: Re: [PATCH 4.19 84/86] dm integrity: fix integrity recalculation
 that is improperly skipped

Hi!

> From: Mikulas Patocka <mpatocka@...hat.com>
> 
> commit 5df96f2b9f58a5d2dc1f30fe7de75e197f2c25f2 upstream.
> 
> Commit adc0daad366b62ca1bce3e2958a40b0b71a8b8b3 ("dm: report suspended
> device during destroy") broke integrity recalculation.
> 
> The problem is dm_suspended() returns true not only during suspend,
> but also during resume. So 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.
> 
> To fix this race condition, add a function dm_post_suspending that is
> only true during the postsuspend phase and use it instead of
> dm_suspended().
> 
> Signed-off-by: Mikulas Patocka <mpatocka redhat com>

Something is wrong with signoff here...

Best regards,
									Pavel

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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