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 (file)
--- a/drivers/char/hvc_xen.c
+++ b/drivers/char/hvc_xen.c
@@ -74,7 +74,8 @@ static int __write_console(const char *data, int len)
        wmb();                  /* write ring before updating pointer */
        intf->out_prod = prod;
 
-       notify_daemon();
+       if (sent)
+               notify_daemon();
        return sent;
 }