hrtimer: Prevent hrtimer_enqueue_reprogram race
authorLeonid Shatz <leonid.shatz@ravellosystems.com>
Mon, 4 Feb 2013 12:33:37 +0000 (14:33 +0200)
committerThomas Gleixner <tglx@linutronix.de>
Tue, 5 Feb 2013 10:52:41 +0000 (11:52 +0100)
commitb22affe0aef429d657bc6505aacb1c569340ddd2
tree6cdb5271ab0f4d02ccca8130fb0c0de8f61fe37a
parent90889a635a9b5488624bccce3ff6b2eec68c007b
hrtimer: Prevent hrtimer_enqueue_reprogram race

hrtimer_enqueue_reprogram contains a race which could result in
timer.base switch during unlock/lock sequence.

hrtimer_enqueue_reprogram is releasing the lock protecting the timer
base for calling raise_softirq_irqsoff() due to a lock ordering issue
versus rq->lock.

If during that time another CPU calls __hrtimer_start_range_ns() on
the same hrtimer, the timer base might switch, before the current CPU
can lock base->lock again and therefor the unlock_timer_base() call
will unlock the wrong lock.

[ tglx: Added comment and massaged changelog ]

Signed-off-by: Leonid Shatz <leonid.shatz@ravellosystems.com>
Signed-off-by: Izik Eidus <izik.eidus@ravellosystems.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/1359981217-389-1-git-send-email-izik.eidus@ravellosystems.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
kernel/hrtimer.c