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xen-devel
[Xen-devel] Re: [PATCH] irq: Exclude percpu IRQs from being fixed up
On 2011/2/17 15:52, Jan Beulich wrote:
On 17.02.11 at 01:15, Fengzhe Zhang<fengzhe.zhang@xxxxxxxxx> wrote:
On 2011/2/16 22:53, Jan Beulich wrote:
On 16.02.11 at 15:26, "Zhang, Fengzhe"<fengzhe.zhang@xxxxxxxxx> wrote:
irq: Exclude percpu IRQs from being fixed up
Xen spin unlock uses spurious ipi "lock_kicker_irq" to wake up blocked vCPUs
waiting on that lock. This irq should always be disabled. However, when Dom0
is shuting down, function fixup_irqs is called which unmasks all irqs.
Function unmask_irq effectively re-enables lock_kicker_irq and its irq
handler
is invoked which reports bug and crashes Dom0.
This patch sets IRQ_PER_CPU flag in irq desc and excludes percpu IRQs from
being fixed up when taking CPUs down.
Signed-off-by: Fengzhe Zhang<fengzhe.zhang@xxxxxxxxx>
diff --git a/arch/x86/kernel/irq_64.c b/arch/x86/kernel/irq_64.c
index 977d8b4..f0f9450 100644
--- a/arch/x86/kernel/irq_64.c
+++ b/arch/x86/kernel/irq_64.c
@@ -80,6 +80,9 @@ void fixup_irqs(void)
if (irq == 2)
continue;
+ if (desc->status& IRQ_PER_CPU)
+ continue;
+
/* interrupt's are disabled at this point */
spin_lock(&desc->lock);
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index f34e231..26bc55a 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -727,10 +727,9 @@ __setup_irq(unsigned int irq, struct irq_desc *desc,
struct irqaction *new)
goto out_thread;
} else
compat_irq_chip_set_default_handler(desc);
-#if defined(CONFIG_IRQ_PER_CPU)
Why? XEN should select IRQ_PER_CPU instead in its Kconfig.
Jan
IRQ_PER_CPU switch is not found in current Kconfig. I'm not sure if this
kernel/irq/Kconfig (introduced as a generic option in 2.6.38-rc2). In
prior kernel you'd have to add a respective Kconfig item in
drivers/xen/Kconfig.
feature is going to be brought back in the short term. I remove the
ifdef to set IRQ_PER_CPU flag in desc by default but still leave the IRQ
handling logic unchanged. This is a temporary solution to fix system
crash on poweroff. And this is the fix with minimum impact among the
several solutions we tried.
But it's more a hack than a fix. And making per-CPU IRQs properly
Yes, that's true. Switching on IRQ_PER_CPU can make this patch neat. But
that isn't my call.
-Fengzhe
treated as such isn't a bad idea in any case, I would say.
Jan
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