xen/hvc: only notify if we actually sent something
Don't spam dom0/xenconsoled with events unless we've actually added
something to the ring.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
diff --git a/drivers/char/hvc_xen.c b/drivers/char/hvc_xen.c
index 60446f8..6b8e6d1 100644
--- a/drivers/char/hvc_xen.c
+++ b/drivers/char/hvc_xen.c
@@ -74,7 +74,8 @@
wmb(); /* write ring before updating pointer */
intf->out_prod = prod;
- notify_daemon();
+ if (sent)
+ notify_daemon();
return sent;
}