* Re: [PATCH] clear irq pending when bypassing it
[not found] <20090430161506.GA2636@typhoon.ccur.com>
@ 2009-04-30 16:49 ` Eric W. Biederman
2009-04-30 18:00 ` Joe Korty
0 siblings, 1 reply; 3+ messages in thread
From: Eric W. Biederman @ 2009-04-30 16:49 UTC (permalink / raw)
To: Joe Korty; +Cc: venkatesh.pallipadi, mingo, linux-kernel
Joe Korty <jak@typhoon.ccur.com> writes:
> IRQ_MOVE_PENDING must be cleared whenever it is bypassed.
>
> Otherwise, we risk an old, pending affinity change
> overtaking and erasing a more recent affinity change that
> had been directly applied (eg, IRQ_MOVE_PCNTXT mode).
When can this happen?
Eric
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] clear irq pending when bypassing it
2009-04-30 16:49 ` [PATCH] clear irq pending when bypassing it Eric W. Biederman
@ 2009-04-30 18:00 ` Joe Korty
2009-04-30 18:43 ` Eric W. Biederman
0 siblings, 1 reply; 3+ messages in thread
From: Joe Korty @ 2009-04-30 18:00 UTC (permalink / raw)
To: Eric W. Biederman
Cc: venkatesh.pallipadi@intel.com, mingo@elte.hu,
linux-kernel@vger.kernel.org
On Thu, Apr 30, 2009 at 12:49:39PM -0400, Eric W. Biederman wrote:
> Joe Korty <jak@typhoon.ccur.com> writes:
>
> > IRQ_MOVE_PENDING must be cleared whenever it is bypassed.
> >
> > Otherwise, we risk an old, pending affinity change
> > overtaking and erasing a more recent affinity change that
> > had been directly applied (eg, IRQ_MOVE_PCNTXT mode).
>
> When can this happen?
Probably doesn't happen. AFAIK, each IRQ is either fully MSI
or non-MSI. The MSI IRQs will always use IRQ_MOVE_PCNTXT and
the non-MSI's will never use IRQ_MOVE_PCNTXT. Thus no collision.
It could only happen if it was possible for a MSI and non-MSI
device to share an IRQ.
Joe
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] clear irq pending when bypassing it
2009-04-30 18:00 ` Joe Korty
@ 2009-04-30 18:43 ` Eric W. Biederman
0 siblings, 0 replies; 3+ messages in thread
From: Eric W. Biederman @ 2009-04-30 18:43 UTC (permalink / raw)
To: Joe Korty
Cc: venkatesh.pallipadi@intel.com, mingo@elte.hu,
linux-kernel@vger.kernel.org
Joe Korty <joe.korty@ccur.com> writes:
> On Thu, Apr 30, 2009 at 12:49:39PM -0400, Eric W. Biederman wrote:
>> Joe Korty <jak@typhoon.ccur.com> writes:
>>
>> > IRQ_MOVE_PENDING must be cleared whenever it is bypassed.
>> >
>> > Otherwise, we risk an old, pending affinity change
>> > overtaking and erasing a more recent affinity change that
>> > had been directly applied (eg, IRQ_MOVE_PCNTXT mode).
>>
>> When can this happen?
>
> Probably doesn't happen. AFAIK, each IRQ is either fully MSI
> or non-MSI. The MSI IRQs will always use IRQ_MOVE_PCNTXT and
> the non-MSI's will never use IRQ_MOVE_PCNTXT. Thus no collision.
>
> It could only happen if it was possible for a MSI and non-MSI
> device to share an IRQ.
Ok. I thought you might have seen something.
It doesn't happen and it can't happen, making your patch wrong.
Eric
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2009-04-30 18:44 UTC | newest]
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[not found] <20090430161506.GA2636@typhoon.ccur.com>
2009-04-30 16:49 ` [PATCH] clear irq pending when bypassing it Eric W. Biederman
2009-04-30 18:00 ` Joe Korty
2009-04-30 18:43 ` Eric W. Biederman
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