Add fatal_signal_pending

Like signal_pending, but it's only true for signals which are fatal to
this process
Signed-off-by: Matthew Wilcox <willy@linux.intel.com>

include/linux/sched.h

@@ -1873,6 +1873,13 @@ static inline int signal_pending(struct task_struct *p)
 	return unlikely(test_tsk_thread_flag(p,TIF_SIGPENDING));
 }
 
+extern int FASTCALL(__fatal_signal_pending(struct task_struct *p));
+
+static inline int fatal_signal_pending(struct task_struct *p)
+{
+	return signal_pending(p) && __fatal_signal_pending(p);
+}
+
 static inline int need_resched(void)
 {
 	return unlikely(test_thread_flag(TIF_NEED_RESCHED));

kernel/signal.c

@@ -994,6 +994,11 @@ void zap_other_threads(struct task_struct *p)
 	}
 }
 
+int fastcall __fatal_signal_pending(struct task_struct *tsk)
+{
+	return sigismember(&tsk->pending.signal, SIGKILL);
+}
+
 /*
  * Must be called under rcu_read_lock() or with tasklist_lock read-held.
  */