[PATCH] powerpc/mpic: supply a .disable callback

[Dongsheng Wang]

From: Wang Dongsheng <dongsheng.wang at freescale.com>

Currently MPIC provides .mask, but not .disable.  This means that
effectively disable_irq() soft-disables the interrupt, and you get
a .mask call if an interrupt actually occurs.

I'm not sure if this was intended as a performance benefit (it seems common
to omit .disable on powerpc interrupt controllers, but nowhere else), but it
interacts badly with threaded/workqueue interrupts (including KVM
reflection).  In such cases, where the real interrupt handler does a
disable_irq_nosync(), schedules defered handling, and returns, we get two
interrupts for every real interrupt.  The second interrupt does nothing
but see that IRQ_DISABLED is set, and decide that it would be a good
idea to actually call .mask.

Signed-off-by: Scott Wood <scottwood at freescale.com>
Signed-off-by: Wang Dongsheng <dongsheng.wang at freescale.com>

diff --git a/arch/powerpc/sysdev/mpic.c b/arch/powerpc/sysdev/mpic.c
index 0e166ed..dd7564b 100644
--- a/arch/powerpc/sysdev/mpic.c
+++ b/arch/powerpc/sysdev/mpic.c
@@ -975,6 +975,7 @@ void mpic_set_destination(unsigned int virq, unsigned int cpuid)
 }
 
 static struct irq_chip mpic_irq_chip = {
+	.irq_disable	= mpic_mask_irq,
 	.irq_mask	= mpic_mask_irq,
 	.irq_unmask	= mpic_unmask_irq,
 	.irq_eoi	= mpic_end_irq,
@@ -984,6 +985,7 @@ static struct irq_chip mpic_irq_chip = {
 
 #ifdef CONFIG_SMP
 static struct irq_chip mpic_ipi_chip = {
+	.irq_disable	= mpic_mask_ipi,
 	.irq_mask	= mpic_mask_ipi,
 	.irq_unmask	= mpic_unmask_ipi,
 	.irq_eoi	= mpic_end_ipi,
@@ -991,6 +993,7 @@ static struct irq_chip mpic_ipi_chip = {
 #endif /* CONFIG_SMP */
 
 static struct irq_chip mpic_tm_chip = {
+	.irq_disable	= mpic_mask_tm,
 	.irq_mask	= mpic_mask_tm,
 	.irq_unmask	= mpic_unmask_tm,
 	.irq_eoi	= mpic_end_irq,
@@ -1001,6 +1004,7 @@ static struct irq_chip mpic_tm_chip = {
 static struct irq_chip mpic_irq_ht_chip = {
 	.irq_startup	= mpic_startup_ht_irq,
 	.irq_shutdown	= mpic_shutdown_ht_irq,
+	.irq_disable	= mpic_mask_irq,
 	.irq_mask	= mpic_mask_irq,
 	.irq_unmask	= mpic_unmask_ht_irq,
 	.irq_eoi	= mpic_end_ht_irq,
-- 
1.8.5