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Subject[PATCH 4/4] xen: do not suspend IPI IRQs.
Date
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: Thomas Gleixner <tglx@linutronix.de>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: xen-devel@lists.xensource.com
Cc: <stable@kernel.org> # .32.x+: 517d6934: irq: rename IRQF_TIMER to IRQF_NO_SUSPEND
Cc: <stable@kernel.org> # .32.x+
---
drivers/xen/events.c | 1 +
1 files changed, 1 insertions(+), 0 deletions(-)
diff --git a/drivers/xen/events.c b/drivers/xen/events.c
index db8f506..28f133a 100644
--- a/drivers/xen/events.c
+++ b/drivers/xen/events.c
@@ -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);
--
1.5.6.5


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