[PATCH 2.6.35 & stable (v2)] powerpc: fix logic error in fixup_irqs

[PATCH 2.6.35 & stable (v2)] powerpc: fix logic error in fixup_irqs

[Johannes Berg]

When SPARSE_IRQ is set, irq_to_desc() can
return NULL. While the code here has a
check for NULL, it's not really correct.
Fix it by separating the check for it.

This fixes CPU hot unplug for me.

Reported-by: Alastair Bridgewater <alastair.bridgewater@gmail.com>
Cc: stable@kernel.org
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
---
v2: cc Alastair, sorry

 arch/powerpc/kernel/irq.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

--- wireless-testing.orig/arch/powerpc/kernel/irq.c	2010-06-11 22:51:08.000000000 +0200
+++ wireless-testing/arch/powerpc/kernel/irq.c	2010-06-11 22:54:11.000000000 +0200
@@ -295,7 +295,10 @@ void fixup_irqs(const struct cpumask *ma
 
 	for_each_irq(irq) {
 		desc = irq_to_desc(irq);
-		if (desc && desc->status & IRQ_PER_CPU)
+		if (!desc)
+			continue;
+
+		if (desc->status & IRQ_PER_CPU)
 			continue;
 
 		cpumask_and(mask, desc->affinity, map);

Re: [PATCH 2.6.35 & stable (v2)] powerpc: fix logic error in fixup_irqs

[Johannes Berg]

On Fri, 2010-06-11 at 22:55 +0200, Johannes Berg wrote:
> When SPARSE_IRQ is set, irq_to_desc() can
> return NULL. While the code here has a
> check for NULL, it's not really correct.
> Fix it by separating the check for it.

Incidentally, there's another quirk in fixup_irqs():

...
        alloc_cpumask_var(&mask, GFP_KERNEL);
...
        local_irq_enable();
        mdelay(1);
        local_irq_disable();


Either it's called with IRQs disabled, in which case it shouldn't do
GFP_KERNEL, or it's called with IRQs enabled, in which case it doesn't
need the local_irq_enable(), no?

johannes

[PATCH 2.6.35 v3] powerpc: fix logic error in fixup_irqs

[Johannes Berg]

When SPARSE_IRQ is set, irq_to_desc() can
return NULL. While the code here has a
check for NULL, it's not really correct.
Fix it by separating the check for it.

This fixes CPU hot unplug for me.

Reported-by: Alastair Bridgewater <alastair.bridgewater@gmail.com>
Cc: stable@kernel.org [2.6.32+]
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
---
v2: cc Alastair, sorry
v3: indicate stable versions

 arch/powerpc/kernel/irq.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

--- wireless-testing.orig/arch/powerpc/kernel/irq.c	2010-06-11 22:51:08.000000000 +0200
+++ wireless-testing/arch/powerpc/kernel/irq.c	2010-06-11 22:54:11.000000000 +0200
@@ -295,7 +295,10 @@ void fixup_irqs(const struct cpumask *ma
 
 	for_each_irq(irq) {
 		desc = irq_to_desc(irq);
-		if (desc && desc->status & IRQ_PER_CPU)
+		if (!desc)
+			continue;
+
+		if (desc->status & IRQ_PER_CPU)
 			continue;
 
 		cpumask_and(mask, desc->affinity, map);