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SubjectRe: [PATCH] Fix lockup related to stop_machine being stuck in __do_softirq.
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On Wed, 2013-06-05 at 21:25 -0700, greearb@candelatech.com wrote:
> From: Ben Greear <greearb@candelatech.com>

> diff --git a/kernel/softirq.c b/kernel/softirq.c
> index 14d7758..f150ad6 100644
> --- a/kernel/softirq.c
> +++ b/kernel/softirq.c
> @@ -204,6 +204,7 @@ EXPORT_SYMBOL(local_bh_enable_ip);
> * should not be able to lock up the box.

Could you update the comment ?

I had the following :

- * We restart softirq processing for at most 2 ms,
- * and if need_resched() is not set.
+ * We restart softirq processing for at most MAX_SOFTIRQ_RESTART times,
+ * but break the loop if need_resched() is set or after 2 ms.


> */
> #define MAX_SOFTIRQ_TIME msecs_to_jiffies(2)
> +#define MAX_SOFTIRQ_RESTART 10
>
> asmlinkage void __do_softirq(void)
> {
> @@ -212,6 +213,7 @@ asmlinkage void __do_softirq(void)
> unsigned long end = jiffies + MAX_SOFTIRQ_TIME;
> int cpu;
> unsigned long old_flags = current->flags;
> + int max_restart = MAX_SOFTIRQ_RESTART;
>
> /*
> * Mask out PF_MEMALLOC s current task context is borrowed for the
> @@ -265,7 +267,8 @@ restart:
>
> pending = local_softirq_pending();
> if (pending) {
> - if (time_before(jiffies, end) && !need_resched())
> + if (time_before(jiffies, end) && !need_resched()
> + && --max_restart)
> goto restart;
>
> wakeup_softirqd();


if (cond1 && cond2 &&
cond3) ...

or

if (cond1 &&
cond2 &&
cond3) ...

Thanks !




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