lguest: fix lguest wake on guest clock tick, or fd activity

The Launcher could be inside the Guest on another CPU; wake_up_process
will do nothing because it is "running".  kick_process will knock it
back into our kernel in this case, otherwise we'll miss it until the
next guest exit.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
diff --git a/drivers/lguest/lguest_user.c b/drivers/lguest/lguest_user.c
index b8ee103..bcdcf34 100644
--- a/drivers/lguest/lguest_user.c
+++ b/drivers/lguest/lguest_user.c
@@ -24,8 +24,8 @@
 
 	if (on) {
 		cpu->break_out = 1;
-		/* Pop it out of the Guest (may be running on different CPU) */
-		wake_up_process(cpu->tsk);
+		if (!wake_up_process(cpu->tsk))
+			kick_process(cpu->tsk);
 		/* Wait for them to reset it */
 		return wait_event_interruptible(cpu->break_wq, !cpu->break_out);
 	} else {