lguest: move process freezing before pending signals check

run_guest tries to freeze the current process after it has handled
pending interrupts and before it calls lguest_arch_run_guest.
This doesn't work nicely if the task has been killed while being frozen
and when we want to handle that signal as soon as possible.
Let's move try_to_freeze before we check for pending signal so that we
can get out of the loop as soon as possible.
Signed-off-by: Michal Hocko <mhocko@suse.cz>
Acked-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

drivers/lguest/core.c

@@ -232,6 +232,13 @@ int run_guest(struct lg_cpu *cpu, unsigned long __user *user)
 			}
 		}
 
+		/*
+		 * All long-lived kernel loops need to check with this horrible
+		 * thing called the freezer.  If the Host is trying to suspend,
+		 * it stops us.
+		 */
+		try_to_freeze();
+
 		/* Check for signals */
 		if (signal_pending(current))
 			return -ERESTARTSYS;
@@ -245,13 +252,6 @@ int run_guest(struct lg_cpu *cpu, unsigned long __user *user)
 		if (irq < LGUEST_IRQS)
 			try_deliver_interrupt(cpu, irq, more);
 
-		/*
-		 * All long-lived kernel loops need to check with this horrible
-		 * thing called the freezer.  If the Host is trying to suspend,
-		 * it stops us.
-		 */
-		try_to_freeze();
-
 		/*
 		 * Just make absolutely sure the Guest is still alive.  One of
 		 * those hypercalls could have been fatal, for example.