Re: [PATCH] irq: Remove unnecessary warning with affinity_hint
From: Ingo Molnar
Date: Wed Apr 08 2015 - 02:28:59 EST
* Seiichi Ikarashi <s.ikarashi@xxxxxxxxxxxxxx> wrote:
> If you turn off a PCI device whose driver has set affinity_hint,
> you will get warning message which does _not_ explain the reason
> why it appeared from the user's point of view.
> # echo 0 > /sys/bus/pci/slots/65/power
> Apr 28 20:29:39 localhost kernel: ------------[ cut here ]------------
> Apr 28 20:29:39 localhost kernel: WARNING: at kernel/irq/manage.c:1002 __free_irq+0x22d/0x250() (Tainted: P --------------- )
> Users will misunderstand some problem has happened
> even though he or she succeeded to turn off the device.
> I suppose this warning was originally for a debug purpose
> for driver developers and has incidentally been left.
> Just remove the warning is good and enough.
> Signed-off-by: Seiichi Ikarashi <s.ikarashi@xxxxxxxxxxxxxx>
> --- a/kernel/irq/manage.c
> +++ b/kernel/irq/manage.c
> @@ -1335,7 +1335,7 @@ static struct irqaction *__free_irq(unsi
> #ifdef CONFIG_SMP
> /* make sure affinity_hint is cleaned up */
> - if (WARN_ON_ONCE(desc->affinity_hint))
> + if (desc->affinity_hint)
> desc->affinity_hint = NULL;
Well, drivers that are using irq_set_affinity_hint() are expected to
to clear the affinity mask, before releasing the irq. This warning
flags drivers that forgot to do that and which might thus leak a
dynamically allocated CPU mask (and/or other resources).
Feel free to turn the warning message into a more informative WARN()
that will blame the driver that triggered it, if the stack dump into
the driver wasn't a clue enough ...
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