aboutsummaryrefslogtreecommitdiffstats
path: root/drivers/xen/events.c
diff options
context:
space:
mode:
Diffstat (limited to 'drivers/xen/events.c')
-rw-r--r--drivers/xen/events.c20
1 files changed, 15 insertions, 5 deletions
diff --git a/drivers/xen/events.c b/drivers/xen/events.c
index d17aa41a9041..aa85881d17b2 100644
--- a/drivers/xen/events.c
+++ b/drivers/xen/events.c
@@ -403,11 +403,23 @@ static void unmask_evtchn(int port)
if (unlikely((cpu != cpu_from_evtchn(port))))
do_hypercall = 1;
- else
+ else {
+ /*
+ * Need to clear the mask before checking pending to
+ * avoid a race with an event becoming pending.
+ *
+ * EVTCHNOP_unmask will only trigger an upcall if the
+ * mask bit was set, so if a hypercall is needed
+ * remask the event.
+ */
+ sync_clear_bit(port, BM(&s->evtchn_mask[0]));
evtchn_pending = sync_test_bit(port, BM(&s->evtchn_pending[0]));
- if (unlikely(evtchn_pending && xen_hvm_domain()))
- do_hypercall = 1;
+ if (unlikely(evtchn_pending && xen_hvm_domain())) {
+ sync_set_bit(port, BM(&s->evtchn_mask[0]));
+ do_hypercall = 1;
+ }
+ }
/* Slow path (hypercall) if this is a non-local port or if this is
* an hvm domain and an event is pending (hvm domains don't have
@@ -418,8 +430,6 @@ static void unmask_evtchn(int port)
} else {
struct vcpu_info *vcpu_info = __this_cpu_read(xen_vcpu);
- sync_clear_bit(port, BM(&s->evtchn_mask[0]));
-
/*
* The following is basically the equivalent of
* 'hw_resend_irq'. Just like a real IO-APIC we 'lose

Privacy Policy