[patch 2/6] x86, intr-remap: Avoid irq_chip mask/unmask in fixup_irqs() for intr-remapping

[Suresh Siddha]

In the presence of interrupt-remapping, irqs will be migrated in the
process context and we don't do (and there is no need to) irq_chip mask/unmask
while migrating the interrupt.

Similarly fix the fixup_irqs() that get called during cpu offline and avoid
calling irq_chip mask/unmask for irqs that are ok to be migrated in the
process context.

While we didn't observe any race condition with the existing code,
this change takes complete advantage of interrupt-remapping in
the newer generation platforms and avoids any potential HW lockup's
(that often worry Eric :)

Signed-off-by: Suresh Siddha <suresh.b.siddha@xxxxxxxxx>
Acked-by: Eric W. Biederman <ebiederm@xxxxxxxxxxxx>
---
 arch/x86/kernel/irq.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Index: tree/arch/x86/kernel/irq.c
===================================================================
--- tree.orig/arch/x86/kernel/irq.c
+++ tree/arch/x86/kernel/irq.c
@@ -308,7 +308,7 @@ void fixup_irqs(void)
 			affinity = cpu_all_mask;
 		}
 
-		if (desc->chip->mask)
+		if (!(desc->status & IRQ_MOVE_PCNTXT) && desc->chip->mask)
 			desc->chip->mask(irq);
 
 		if (desc->chip->set_affinity)
@@ -316,7 +316,7 @@ void fixup_irqs(void)
 		else if (!(warned++))
 			set_affinity = 0;
 
-		if (desc->chip->unmask)
+		if (!(desc->status & IRQ_MOVE_PCNTXT) && desc->chip->unmask)
 			desc->chip->unmask(irq);
 
 		spin_unlock(&desc->lock);


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