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>

2 files changed, 5 insertions, 5 deletions

diff --git a/drivers/lguest/interrupts_and_traps.c b/drivers/lguest/interrupts_and_traps.c
index 6e99adbe194..9ea26ad88c9 100644
--- a/drivers/lguest/interrupts_and_traps.c
+++ b/drivers/lguest/interrupts_and_traps.c
@@ -511,9 +511,9 @@ static enum hrtimer_restart clockdev_fn(struct hrtimer *timer)
 
         /* Remember the first interrupt is the timer interrupt. */
         set_bit(0, cpu->irqs_pending);
-        /* If the Guest is actually stopped, we need to wake it up. */
-        if (cpu->halted)
-                wake_up_process(cpu->tsk);
+        /* Guest may be stopped or running on another CPU. */
+        if (!wake_up_process(cpu->tsk))
+                kick_process(cpu->tsk);
         return HRTIMER_NORESTART;
 }
 
diff --git a/drivers/lguest/lguest_user.c b/drivers/lguest/lguest_user.c
index b8ee103eed5..bcdcf3453e7 100644
--- a/drivers/lguest/lguest_user.c
+++ b/drivers/lguest/lguest_user.c
@@ -24,8 +24,8 @@ static int break_guest_out(struct lg_cpu *cpu, const unsigned long __user*input)
 
         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 {