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xen/manage: fix potential deadlock when resuming the console 

Calling xen_console_resume() in xen_suspend() causes a warning because
it locks irq_mapping_update_lock (a mutex) and this may sleep.  If a
userspace process is using the evtchn device then this mutex may be
locked at the point of the stop_machine() call and
xen_console_resume() would then deadlock.

Resuming the console after stop_machine() returns avoids this
deadlock.

Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: <stable@vger.kernel.org>
This commit is contained in:
David Vrabel 2014-07-02 17:25:23 +01:00
parent 13cd36a37a
commit 1b6478231c
1 changed files with 4 additions and 1 deletions
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5
drivers/xen/manage.c
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@ -88,7 +88,6 @@ static int xen_suspend(void *data)
if (!si->cancelled) {
xen_irq_resume();
xen_console_resume();
xen_timer_resume();
}
@ -135,6 +134,10 @@ static void do_suspend(void)
err = stop_machine(xen_suspend, &si, cpumask_of(0));
/* Resume console as early as possible. */
if (!si.cancelled)
xen_console_resume();
raw_notifier_call_chain(&xen_resume_notifier, 0, NULL);
dpm_resume_start(si.cancelled ? PMSG_THAW : PMSG_RESTORE);