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xen: don't worry about preempt during xen_irq_enable() 

When enabling interrupts, we don't need to worry about preemption,
because we either enter with interrupts disabled - so no preemption -
or the caller is confused and is re-enabling interrupts on some
indeterminate processor.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Jeremy Fitzhardinge 2008-05-26 23:31:05 +01:00 committed by Thomas Gleixner
parent 2956a3511c
commit 239d1fc04e
1 changed files with 5 additions and 5 deletions
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10
arch/x86/xen/enlighten.c
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@ -235,13 +235,13 @@ static void xen_irq_enable(void)
{
struct vcpu_info *vcpu;
/* There's a one instruction preempt window here. We need to
make sure we're don't switch CPUs between getting the vcpu
pointer and updating the mask. */
preempt_disable();
/* We don't need to worry about being preempted here, since
either a) interrupts are disabled, so no preemption, or b)
the caller is confused and is trying to re-enable interrupts
on an indeterminate processor. */
vcpu = x86_read_percpu(xen_vcpu);
vcpu->evtchn_upcall_mask = 0;
preempt_enable_no_resched();
/* Doesn't matter if we get preempted here, because any
pending event will get dealt with anyway. */