Re: Interrupt randomness in 3.14.10-rt

From: Thomas Gleixner
Date: Fri Jul 11 2014 - 03:24:43 EST


On Fri, 11 Jul 2014, Ben Hutchings wrote:

> I noticed this change between 3.14.3-rt5 and 3.14.10-rt7:
>
> --- debian/patches/features/all/rt/random-make-it-work-on-rt.patch (revision 21522)
> +++ debian/patches/features/all/rt/random-make-it-work-on-rt.patch (working copy)
> [...]
> ---- a/kernel/irq/manage.c
> -+++ b/kernel/irq/manage.c
> -@@ -942,6 +942,12 @@ static int irq_thread(void *data)
> - if (action_ret == IRQ_HANDLED)
> - atomic_inc(&desc->threads_handled);
> -
> -+#ifdef CONFIG_PREEMPT_RT_FULL
> -+ migrate_disable();
> -+ add_interrupt_randomness(action->irq, 0,
> -+ desc->random_ip ^ (unsigned long) action);
> -+ migrate_enable();
> -+#endif
> - wake_threads_waitq(desc);
> - }
> -
>
> (I.e. old patch included these additions, new patch doesn't.)
>
> Evidently this was made in the announced 3.14.10-rt6, not -rt7. Was it
> intentional? Now irq_desc::random_ip is set but never used.

Hmm, how did I lose that one? Thanks for spotting it! I'll pick it up for rt8

tglx

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