linux-kernel - [tip:irq/core] softirq: Avoid stack switch from ksoftirqd

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Date:	Tue, 8 Feb 2011 18:39:43 GMT
From:	tip-bot for Thomas Gleixner <tglx@...utronix.de>
To:	linux-tip-commits@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, hpa@...or.com, mingo@...hat.com,
	peterz@...radead.org, lethal@...ux-sh.org, davem@...emloft.net,
	benh@...nel.crashing.org, heiko.carstens@...ibm.com,
	frank.rowand@...sony.com, tglx@...utronix.de
Subject: [tip:irq/core] softirq: Avoid stack switch from ksoftirqd

Commit-ID:  c305d524e5dd3c3c7a6035083e30950bea1b52dc
Gitweb:     http://git.kernel.org/tip/c305d524e5dd3c3c7a6035083e30950bea1b52dc
Author:     Thomas Gleixner <tglx@...utronix.de>
AuthorDate: Wed, 2 Feb 2011 17:10:48 +0100
Committer:  Thomas Gleixner <tglx@...utronix.de>
CommitDate: Tue, 8 Feb 2011 19:37:12 +0100

softirq: Avoid stack switch from ksoftirqd

ksoftirqd() calls do_softirq() which switches stacks on several
architectures. That makes no sense at all. ksoftirqd's stack is
sufficient.

Call __do_softirq() directly.

Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Acked-by: Peter Zijlstra <peterz@...radead.org>
Cc: Benjamin Herrenschmidt <benh@...nel.crashing.org>
Cc: Heiko Carstens <heiko.carstens@...ibm.com>
Acked-by: David Miller <davem@...emloft.net>
Cc: Paul Mundt <lethal@...ux-sh.org>
Reviewed-by: Frank Rowand <frank.rowand@...sony.com>
LKML-Reference: <alpine.LFD.2.00.1102021704530.31804@...alhost6.localdomain6>
---
 kernel/softirq.c |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)

diff --git a/kernel/softirq.c b/kernel/softirq.c
index 68eb5ef..c049046 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -738,7 +738,10 @@ static int run_ksoftirqd(void * __bind_cpu)
 			   don't process */
 			if (cpu_is_offline((long)__bind_cpu))
 				goto wait_to_die;
-			do_softirq();
+			local_irq_disable();
+			if (local_softirq_pending())
+				__do_softirq();
+			local_irq_enable();
 			preempt_enable_no_resched();
 			cond_resched();
 			preempt_disable();
--
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