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* [PATCH] softirq: Avoid stack switch from ksoftirqd
@ 2011-02-02 16:10 Thomas Gleixner
  2011-02-02 16:24 ` Peter Zijlstra
                   ` (3 more replies)
  0 siblings, 4 replies; 5+ messages in thread
From: Thomas Gleixner @ 2011-02-02 16:10 UTC (permalink / raw)
  To: LKML
  Cc: Peter Zijlstra, Ingo Molnar, Benjamin Herrenschmidt,
	Heiko Carstens, David Miller, Paul Mundt

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@linutronix.de>
---
 kernel/softirq.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

Index: linux-2.6-tip/kernel/softirq.c
===================================================================
--- linux-2.6-tip.orig/kernel/softirq.c
+++ linux-2.6-tip/kernel/softirq.c
@@ -738,7 +738,10 @@ static int run_ksoftirqd(void * __bind_c
 			   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();

^ permalink raw reply	[flat|nested] 5+ messages in thread

* Re: [PATCH] softirq: Avoid stack switch from ksoftirqd
  2011-02-02 16:10 [PATCH] softirq: Avoid stack switch from ksoftirqd Thomas Gleixner
@ 2011-02-02 16:24 ` Peter Zijlstra
  2011-02-02 21:51 ` David Miller
                   ` (2 subsequent siblings)
  3 siblings, 0 replies; 5+ messages in thread
From: Peter Zijlstra @ 2011-02-02 16:24 UTC (permalink / raw)
  To: Thomas Gleixner
  Cc: LKML, Ingo Molnar, Benjamin Herrenschmidt, Heiko Carstens,
	David Miller, Paul Mundt

On Wed, 2011-02-02 at 17:10 +0100, Thomas Gleixner wrote:
> 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@linutronix.de>

Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>

> ---
>  kernel/softirq.c |    5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> Index: linux-2.6-tip/kernel/softirq.c
> ===================================================================
> --- linux-2.6-tip.orig/kernel/softirq.c
> +++ linux-2.6-tip/kernel/softirq.c
> @@ -738,7 +738,10 @@ static int run_ksoftirqd(void * __bind_c
>  			   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();




^ permalink raw reply	[flat|nested] 5+ messages in thread

* Re: [PATCH] softirq: Avoid stack switch from ksoftirqd
  2011-02-02 16:10 [PATCH] softirq: Avoid stack switch from ksoftirqd Thomas Gleixner
  2011-02-02 16:24 ` Peter Zijlstra
@ 2011-02-02 21:51 ` David Miller
  2011-02-02 23:32 ` Frank Rowand
  2011-02-08 18:39 ` [tip:irq/core] " tip-bot for Thomas Gleixner
  3 siblings, 0 replies; 5+ messages in thread
From: David Miller @ 2011-02-02 21:51 UTC (permalink / raw)
  To: tglx; +Cc: linux-kernel, peterz, mingo, benh, heiko.carstens, lethal

From: Thomas Gleixner <tglx@linutronix.de>
Date: Wed, 2 Feb 2011 17:10:48 +0100 (CET)

> 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@linutronix.de>

Acked-by: David S. Miller <davem@davemloft.net>

^ permalink raw reply	[flat|nested] 5+ messages in thread

* Re: [PATCH] softirq: Avoid stack switch from ksoftirqd
  2011-02-02 16:10 [PATCH] softirq: Avoid stack switch from ksoftirqd Thomas Gleixner
  2011-02-02 16:24 ` Peter Zijlstra
  2011-02-02 21:51 ` David Miller
@ 2011-02-02 23:32 ` Frank Rowand
  2011-02-08 18:39 ` [tip:irq/core] " tip-bot for Thomas Gleixner
  3 siblings, 0 replies; 5+ messages in thread
From: Frank Rowand @ 2011-02-02 23:32 UTC (permalink / raw)
  To: Thomas Gleixner
  Cc: LKML, Peter Zijlstra, Ingo Molnar, Benjamin Herrenschmidt,
	Heiko Carstens, David Miller, Paul Mundt

On 02/02/11 08:10, Thomas Gleixner wrote:
> 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@linutronix.de>

Reviewed-by: Frank Rowand <frank.rowand@am.sony.com>

> ---
>  kernel/softirq.c |    5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> Index: linux-2.6-tip/kernel/softirq.c
> ===================================================================
> --- linux-2.6-tip.orig/kernel/softirq.c
> +++ linux-2.6-tip/kernel/softirq.c
> @@ -738,7 +738,10 @@ static int run_ksoftirqd(void * __bind_c
>  			   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();
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/
> 



^ permalink raw reply	[flat|nested] 5+ messages in thread

* [tip:irq/core] softirq: Avoid stack switch from ksoftirqd
  2011-02-02 16:10 [PATCH] softirq: Avoid stack switch from ksoftirqd Thomas Gleixner
                   ` (2 preceding siblings ...)
  2011-02-02 23:32 ` Frank Rowand
@ 2011-02-08 18:39 ` tip-bot for Thomas Gleixner
  3 siblings, 0 replies; 5+ messages in thread
From: tip-bot for Thomas Gleixner @ 2011-02-08 18:39 UTC (permalink / raw)
  To: linux-tip-commits
  Cc: linux-kernel, hpa, mingo, peterz, lethal, davem, benh,
	heiko.carstens, frank.rowand, tglx

Commit-ID:  c305d524e5dd3c3c7a6035083e30950bea1b52dc
Gitweb:     http://git.kernel.org/tip/c305d524e5dd3c3c7a6035083e30950bea1b52dc
Author:     Thomas Gleixner <tglx@linutronix.de>
AuthorDate: Wed, 2 Feb 2011 17:10:48 +0100
Committer:  Thomas Gleixner <tglx@linutronix.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@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Acked-by: David Miller <davem@davemloft.net>
Cc: Paul Mundt <lethal@linux-sh.org>
Reviewed-by: Frank Rowand <frank.rowand@am.sony.com>
LKML-Reference: <alpine.LFD.2.00.1102021704530.31804@localhost6.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();

^ permalink raw reply	[flat|nested] 5+ messages in thread

end of thread, other threads:[~2011-02-08 18:40 UTC | newest]

Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2011-02-02 16:10 [PATCH] softirq: Avoid stack switch from ksoftirqd Thomas Gleixner
2011-02-02 16:24 ` Peter Zijlstra
2011-02-02 21:51 ` David Miller
2011-02-02 23:32 ` Frank Rowand
2011-02-08 18:39 ` [tip:irq/core] " tip-bot for Thomas Gleixner

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