linux-kernel - futex: priority wakeup miss ordering

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Message-Id: <1210195378.17132.237.camel@localhost.localdomain>
Date:	Wed, 07 May 2008 14:22:58 -0700
From:	Daniel Walker <dwalker@...sta.com>
To:	Pierre Peiffer <pierre.peiffer@...l.net>
Cc:	linux-kernel@...r.kernel.org
Subject: futex: priority wakeup miss ordering

from commit ec92d08292d3e9b0823eba138a4564d2d39f25c7

The wakeup ordering should be in priority order. However if the priority
of a task is modified while it's waiting on the futex you will get an
out of order wakeup.

If you use a priority inheriting mutex this is correct. It's because the
rtmutex hooks into sched_setscheduler to catch any priority changes,
then re-queues with the new priority.. But the futex doesn't have this
hook.

Was this intentionally left out of this priority wake up patch? I
thought I would let you know in case you had a specific reason for not
handling this.. 

Daniel

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