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>

diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index f687648..4a372b7 100644 (file)
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -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. */