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x86, irq: Remove IRQ_DISABLED check in process context IRQ move

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As discussed in the thread here:

  http://marc.info/?l=linux-kernel&m=123964468521142&w=2

Eric W. Biederman observed:

> It looks like some additional bugs have slipped in since last I looked.
>
> set_irq_affinity does this:
> ifdef CONFIG_GENERIC_PENDING_IRQ
>        if (desc->status & IRQ_MOVE_PCNTXT || desc->status & IRQ_DISABLED) {
>                cpumask_copy(desc->affinity, cpumask);
>                desc->chip->set_affinity(irq, cpumask);
>        } else {
>                desc->status |= IRQ_MOVE_PENDING;
>                cpumask_copy(desc->pending_mask, cpumask);
>        }
> #else
>
> That IRQ_DISABLED case is a software state and as such it has nothing to
> do with how safe it is to move an irq in process context.

[...]

>
> The only reason we migrate MSIs in interrupt context today is that there
> wasn't infrastructure for support migration both in interrupt context
> and outside of it.

Yes. The idea here was to force the MSI migration to happen in process
context. One of the patches in the series did

        disable_irq(dev->irq);
        irq_set_affinity(dev->irq, cpumask_of(dev->cpu));
        enable_irq(dev->irq);

with the above patch adding irq/manage code check for interrupt disabled
and moving the interrupt in process context.

IIRC, there was no IRQ_MOVE_PCNTXT when we were developing this HPET
code and we ended up having this ugly hack. IRQ_MOVE_PCNTXT was there
when we eventually submitted the patch upstream. But, looks like I did a
blind rebasing instead of using IRQ_MOVE_PCNTXT in hpet MSI code.

Below patch fixes this. i.e., revert commit 932775a4ab
and add PCNTXT to HPET MSI setup. Also removes copying of desc->affinity
in generic code as set_affinity routines are doing it internally.

Reported-by: "Eric W. Biederman" <[email protected]>
Signed-off-by: Venkatesh Pallipadi <[email protected]>
Acked-by: "Eric W. Biederman" <[email protected]>
Cc: "Li Shaohua" <[email protected]>
Cc: Gary Hade <[email protected]>
Cc: "[email protected]" <[email protected]>
Cc: [email protected]
LKML-Reference: <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
This commit is contained in:
Pallipadi, Venkatesh 2009-04-13 15:20:58 -07:00 • committed by Ingo Molnar
commit 6ec3cfeca0
2 changed files with 4 additions and 3 deletions
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5
kernel/irq/manage.c
View file

@ -109,10 +109,9 @@ int irq_set_affinity(unsigned int irq, const struct cpumask *cpumask)
spin_lock_irqsave(&desc->lock, flags);
#ifdef CONFIG_GENERIC_PENDING_IRQ
if (desc->status & IRQ_MOVE_PCNTXT || desc->status & IRQ_DISABLED) {
cpumask_copy(desc->affinity, cpumask);
if (desc->status & IRQ_MOVE_PCNTXT)
desc->chip->set_affinity(irq, cpumask);
} else {
else {
desc->status |= IRQ_MOVE_PENDING;
cpumask_copy(desc->pending_mask, cpumask);
}