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xen: Do not suspend IPI IRQs.

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In general the semantics of IPIs are that they are are expected to
continue functioning after dpm_suspend_noirq().

Specifically I have seen a deadlock between the callfunc IPI and the
stop machine used by xen's do_suspend() routine. If one CPU has already
called dpm_suspend_noirq() then there is a window where it can be sent
a callfunc IPI before all the other CPUs have entered stop_cpu().

If this happens then the first CPU ends up spinning in stop_cpu()
waiting for the other to rendezvous in state STOPMACHINE_PREPARE while
the other is spinning in csd_lock_wait().

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: xen-devel@lists.xensource.com
LKML-Reference: <1280398595-29708-4-git-send-email-ian.campbell@citrix.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Ian Campbell 2010-07-29 11:16:35 +01:00 committed by Thomas Gleixner
parent ba461f094b
commit 4877c73728
1 changed files with 1 additions and 0 deletions
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1
drivers/xen/events.c
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@ -536,6 +536,7 @@ int bind_ipi_to_irqhandler(enum ipi_vector ipi,
if (irq < 0)
return irq;
irqflags |= IRQF_NO_SUSPEND;
retval = request_irq(irq, handler, irqflags, devname, dev_id);
if (retval != 0) {
unbind_from_irq(irq);