lkml.org 
[lkml]   [2015]   [May]   [18]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH - RE-RESEND] IRQ: don't suspend nested_thread irqs over system suspend.
On Sun, May 17, 2015 at 03:19:34PM +1000, NeilBrown wrote:
>
>
> Nested IRQs can only fire when the parent irq fires.
> So when the parent is suspended, there is no need to suspend
> the child irq.
>
> Suspending nested irqs can cause a problem is they are suspended or
> resumed in the wrong order.
> If an interrupt fires while the parent is active but the child is
> suspended, then the interrupt will not be acknowledged properly
> and so an interrupt storm can result.
> This is particularly likely if the parent is resumed before
> the child, and the interrupt was raised during suspend.
>
> Ensuring correct ordering would be possible, but it is simpler
> to just never suspend nested interrupts.

Looks sane to me, but it's Thomas' call.

FWIW:

Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>

>
> Signed-off-by: NeilBrown <neil@brown.name>
> ---
> diff --git a/kernel/irq/pm.c b/kernel/irq/pm.c
> index 5204a6d1b985..d22786a6dbde 100644
> --- a/kernel/irq/pm.c
> +++ b/kernel/irq/pm.c
> @@ -123,6 +123,8 @@ void suspend_device_irqs(void)
> unsigned long flags;
> bool sync;
>
> + if (irq_settings_is_nested_thread(desc))
> + continue;
> raw_spin_lock_irqsave(&desc->lock, flags);
> sync = suspend_device_irq(desc, irq);
> raw_spin_unlock_irqrestore(&desc->lock, flags);
> @@ -163,6 +165,8 @@ static void resume_irqs(bool want_early)
>
> if (!is_early && want_early)
> continue;
> + if (irq_settings_is_nested_thread(desc))
> + continue;
>
> raw_spin_lock_irqsave(&desc->lock, flags);
> resume_irq(desc, irq);




\
 
 \ /
  Last update: 2015-05-18 14:41    [W:0.056 / U:1.744 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site