Re: [PATCH] softirq: Avoid stack switch from ksoftirqd

From: Frank Rowand
Date: Wed Feb 02 2011 - 18:32:55 EST


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@xxxxxxxxxxxxx>

Reviewed-by: Frank Rowand <frank.rowand@xxxxxxxxxxx>

> ---
> 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();
> --
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