From 5d60d3e7c08a46643e902e39d9743cf394382151 Mon Sep 17 00:00:00 2001
From: Frederic Weisbecker <fweisbec@gmail.com>
Date: Tue, 24 Sep 2013 04:11:35 +0200
Subject: [PATCH] irq: Improve a bit softirq debugging

do_softirq() has a debug check that verifies that it is not nesting
on softirqs processing, nor miscounting the softirq part of the preempt
count.

But making sure that softirqs processing don't nest is actually a more
generic concern that applies to any caller of __do_softirq().

Do take it one step further and generalize that debug check to
any softirq processing.

Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@au1.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Mackerras <paulus@au1.ibm.com>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: James E.J. Bottomley <jejb@parisc-linux.org>
Cc: Helge Deller <deller@gmx.de>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Andrew Morton <akpm@linux-foundation.org>
---
 kernel/softirq.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/softirq.c b/kernel/softirq.c
index 17c5cd2e3dae..9f8092b82a94 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -133,7 +133,6 @@ EXPORT_SYMBOL(local_bh_disable);
 
 static void __local_bh_enable(unsigned int cnt)
 {
-	WARN_ON_ONCE(in_irq());
 	WARN_ON_ONCE(!irqs_disabled());
 
 	if (softirq_count() == cnt)
@@ -148,6 +147,7 @@ static void __local_bh_enable(unsigned int cnt)
  */
 void _local_bh_enable(void)
 {
+	WARN_ON_ONCE(in_irq());
 	__local_bh_enable(SOFTIRQ_DISABLE_OFFSET);
 }
 
@@ -279,6 +279,7 @@ restart:
 
 	account_irq_exit_time(current);
 	__local_bh_enable(SOFTIRQ_OFFSET);
+	WARN_ON_ONCE(in_interrupt());
 	tsk_restore_flags(current, old_flags, PF_MEMALLOC);
 }
 
@@ -299,7 +300,6 @@ asmlinkage void do_softirq(void)
 	if (pending)
 		do_softirq_own_stack();
 
-	WARN_ON_ONCE(softirq_count());
 	local_irq_restore(flags);
 }