linux-kernel - [tip:irq/urgent] irq: Ensure irq_exit() code runs with interrupts disabled

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Date:	Thu, 21 Feb 2013 12:05:56 -0800
From:	tip-bot for Thomas Gleixner <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, hpa@...or.com, mingo@...nel.org,
	torvalds@...uxfoundation.org, peterz@...radead.org,
	paulmck@...ux.vnet.ibm.com, fweisbec@...il.com, tglx@...utronix.de
Subject: [tip:irq/urgent] irq: Ensure irq_exit()
  code runs with interrupts disabled

Commit-ID:  74eed0163d0def3fce27228d9ccf3d36e207b286
Gitweb:     http://git.kernel.org/tip/74eed0163d0def3fce27228d9ccf3d36e207b286
Author:     Thomas Gleixner <tglx@...utronix.de>
AuthorDate: Wed, 20 Feb 2013 22:00:48 +0100
Committer:  Thomas Gleixner <tglx@...utronix.de>
CommitDate: Thu, 21 Feb 2013 20:52:24 +0100

irq: Ensure irq_exit() code runs with interrupts disabled

We had already a few problems with code called from irq_exit() when
interrupted from a nesting interrupt. This can happen on architectures
which do not define __ARCH_IRQ_EXIT_IRQS_DISABLED.

__ARCH_IRQ_EXIT_IRQS_DISABLED should go away and we want to make it
mandatory to call irq_exit() with interrupts disabled.

As a temporary protection disable interrupts for those architectures
which do not define __ARCH_IRQ_EXIT_IRQS_DISABLED and add a WARN_ONCE
when an architecture which defines __ARCH_IRQ_EXIT_IRQS_DISABLED calls
irq_exit() with interrupts enabled.

Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Cc: Frederic Weisbecker <fweisbec@...il.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Ingo Molnar <mingo@...nel.org>
Cc: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@...uxfoundation.org>
Link: http://lkml.kernel.org/r/alpine.LFD.2.02.1302202155320.22263@ionos

---
 kernel/softirq.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/kernel/softirq.c b/kernel/softirq.c
index f5cc25f..f2a9346 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -341,6 +341,14 @@ static inline void invoke_softirq(void)
  */
 void irq_exit(void)
 {
+#ifndef __ARCH_IRQ_EXIT_IRQS_DISABLED
+	unsigned long flags;
+
+	local_irq_save(flags);
+#else
+	WARN_ON_ONCE(!irqs_disabled());
+#endif
+
 	account_irq_exit_time(current);
 	trace_hardirq_exit();
 	sub_preempt_count(IRQ_EXIT_OFFSET);
@@ -354,6 +362,9 @@ void irq_exit(void)
 #endif
 	rcu_irq_exit();
 	sched_preempt_enable_no_resched();
+#ifndef __ARCH_IRQ_EXIT_IRQS_DISABLED
+	local_irq_restore(flags);
+#endif
 }

 /*
--
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