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xen/manage: Always freeze/thaw processes when suspend/resuming 

Always freeze processes when suspending and thaw processes when resuming
to prevent a race noticeable with HVM guests.

This prevents a deadlock where the khubd kthread (which is designed to
be freezable) acquires a usb device lock and then tries to allocate
memory which requires the disk which hasn't been resumed yet.
Meanwhile, the xenwatch thread deadlocks waiting for the usb device
lock.

Freezing processes fixes this because the khubd thread is only thawed
after the xenwatch thread finishes resuming all the devices.

Signed-off-by: Ross Lagerwall <ross.lagerwall@citrix.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Cc: stable@vger.kernel.org
This commit is contained in:
Ross Lagerwall 2014-08-18 10:41:36 +01:00 committed by David Vrabel
parent 7d951f3ccb
commit 61a734d305
1 changed files with 0 additions and 7 deletions
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7
drivers/xen/manage.c
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@ -103,16 +103,11 @@ static void do_suspend(void)
shutting_down = SHUTDOWN_SUSPEND;
#ifdef CONFIG_PREEMPT
/* If the kernel is preemptible, we need to freeze all the processes
to prevent them from being in the middle of a pagetable update
during suspend. */
err = freeze_processes();
if (err) {
pr_err("%s: freeze failed %d\n", __func__, err);
goto out;
}
#endif
err = dpm_suspend_start(PMSG_FREEZE);
if (err) {
@ -157,10 +152,8 @@ static void do_suspend(void)
dpm_resume_end(si.cancelled ? PMSG_THAW : PMSG_RESTORE);
out_thaw:
#ifdef CONFIG_PREEMPT
thaw_processes();
out:
#endif
shutting_down = SHUTDOWN_INVALID;
}
#endif /* CONFIG_HIBERNATE_CALLBACKS */