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irq: remove unneeded desc->chip->ack check

PATCH In review Wang Chen 2 participants 4 messages Dec 26, 2008 – Dec 29, 2008 IRQ

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Wang Chen

author
#0 lore raw

PATCH 1/2 irq: remove unneeded desc->chip->ack check

desc->chip->ack is initialized to ack_bad().
It will not be NULL.

Signed-off-by Wang Chen <[email protected]>
---
 kernel/irq/chip.c   |    3 +--
 kernel/irq/handle.c |   14 +++++---------
 2 files changed, 6 insertions(+), 11 deletions(-)
kernel/irq/chip.c +1 -2
index f63c706..b929803 100644
@@ -530,8 +530,7 @@ handle_percpu_irq(unsigned int irq, struct irq_desc *desc)
 
 	kstat_incr_irqs_this_cpu(irq, desc);
 
-	if (desc->chip->ack)
-		desc->chip->ack(irq);
+	desc->chip->ack(irq);
 
 	action_ret = handle_IRQ_event(irq, desc->action);
 	if (!noirqdebug)
kernel/irq/handle.c +5 -9
index 6492400..4408672 100644
@@ -337,11 +337,9 @@ unsigned int __do_IRQ(unsigned int irq)
 		/*
 		 * No locking required for CPU-local interrupts:
 		 */
-		if (desc->chip->ack) {
-			desc->chip->ack(irq);
-			/* get new one */
-			desc = irq_remap_to_desc(irq, desc);
-		}
+		desc->chip->ack(irq);
+		/* get new one */
+		desc = irq_remap_to_desc(irq, desc);
 		if (likely(!(desc->status & IRQ_DISABLED))) {
 			action_ret = handle_IRQ_event(irq, desc->action);
 			if (!noirqdebug)

@@ -352,10 +350,8 @@ unsigned int __do_IRQ(unsigned int irq)
 	}
 
 	spin_lock(&desc->lock);
-	if (desc->chip->ack) {
-		desc->chip->ack(irq);
-		desc = irq_remap_to_desc(irq, desc);
-	}
+	desc->chip->ack(irq);
+	desc = irq_remap_to_desc(irq, desc);
 	/*
 	 * REPLAY is when Linux resends an IRQ that was dropped earlier
 	 * WAITING is used by probe to mark irqs that are being tested
Signature · 1 line
1.5.3.4
#1 lore raw
Quoted 2 lines · Wang Chen

desc->chip->ack is initialized to ack_bad().
It will not be NULL.

hm, that is only true of no_irq_chip() - is it true of all irq_chip definitions on all architectures?

Ingo

author
#2 lore raw

PATCH 1/1 irq: check chip->ack before calling (WAS: irq: remove unneeded desc->chip->ack check)

Ingo Molnar said the following on 2008-12-26 21:27:

Quoted 8 lines · Wang Chen
Quoted 3 lines

desc->chip->ack is initialized to ack_bad().
It will not be NULL.

hm, that is only true of no_irq_chip() - is it true of all irq_chip definitions on all architectures?

No, some arch's irq_chip doesn't have ack routine.
So I was wrong.
But this enlighten another thought that generic irq layer doesn't know whether irq_chip has ack routine on some architectures. Upon that, before calling chip->ack, should check it's not NULL.

Impact: fix theoretic NULL dereference

Signed-off-by Wang Chen <[email protected]>

---

kernel/irq/chip.c +4 -2
index f63c706..9a7fbb8 100644
@@ -290,7 +290,8 @@ static inline void mask_ack_irq(struct irq_desc *desc, int irq)
 		desc->chip->mask_ack(irq);
 	else {
 		desc->chip->mask(irq);
-		desc->chip->ack(irq);
+		if (desc->chip->ack)
+			desc->chip->ack(irq);
 	}
 }
 

@@ -475,7 +476,8 @@ handle_edge_irq(unsigned int irq, struct irq_desc *desc)
 	kstat_incr_irqs_this_cpu(irq, desc);
 
 	/* Start handling the irq */
-	desc->chip->ack(irq);
+	if (desc->chip->ack)
+		desc->chip->ack(irq);
 	desc = irq_remap_to_desc(irq, desc);
 
 	/* Mark the IRQ currently in progress.*/
Applied
#3 lore raw

Re: [PATCH -tip] irq: check chip->ack before calling (WAS: irq: remove unneeded desc->chip->ack check)

Quoted 16 lines · Wang Chen

Ingo Molnar said the following on 2008-12-26 21:27:

Quoted 8 lines · Wang Chen
Quoted 3 lines

desc->chip->ack is initialized to ack_bad().
It will not be NULL.

hm, that is only true of no_irq_chip() - is it true of all irq_chip definitions on all architectures?

No, some arch's irq_chip doesn't have ack routine.
So I was wrong.
But this enlighten another thought that generic irq layer doesn't know whether irq_chip has ack routine on some architectures. Upon that, before calling chip->ack, should check it's not NULL.

Quoted 3 lines

Impact: fix theoretic NULL dereference

Signed-off-by Wang Chen <[email protected]>

applied to tip/irq/genirq, thanks!

(find below how the final commit message ended up looking like.)

Ingo

------------------>

Quoted 1 line

From efdc64f0c792ea744bcc9203f35b908e66d42f41 Mon Sep 17 00:00:00 2001

From: Wang Chen <[email protected]>
Date: Mon, 29 Dec 2008 13:35:11 +0800
Subject: [PATCH] genirq: check chip->ack before calling

Impact: fix theoretical NULL dereference

The generic irq layer doesn't know whether irq_chip has ack routine on some architectures or not. Upon that, before calling chip->ack, we should check that it's not NULL.

Signed-off-by Wang Chen <[email protected]>
Signed-off-by Ingo Molnar <[email protected]>
---
 kernel/irq/chip.c |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)
kernel/irq/chip.c +4 -2
index 6eb3c79..0ad02d7 100644
@@ -290,7 +290,8 @@ static inline void mask_ack_irq(struct irq_desc *desc, int irq)
 		desc->chip->mask_ack(irq);
 	else {
 		desc->chip->mask(irq);
-		desc->chip->ack(irq);
+		if (desc->chip->ack)
+			desc->chip->ack(irq);
 	}
 }
 

@@ -475,7 +476,8 @@ handle_edge_irq(unsigned int irq, struct irq_desc *desc)
 	kstat_incr_irqs_this_cpu(irq, desc);
 
 	/* Start handling the irq */
-	desc->chip->ack(irq);
+	if (desc->chip->ack)
+		desc->chip->ack(irq);
 	desc = irq_remap_to_desc(irq, desc);
 
 	/* Mark the IRQ currently in progress.*/