1 files changed, 12 insertions, 6 deletions

diff --git a/kernel/signal.c b/kernel/signal.c
index b3f78d09a105..bb0efa5705ed 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1629,10 +1629,8 @@ bool do_notify_parent(struct task_struct *tsk, int sig)
 	info.si_uid = __task_cred(tsk)->uid;
 	rcu_read_unlock();
 
-	info.si_utime = cputime_to_clock_t(cputime_add(tsk->utime,
-				tsk->signal->utime));
-	info.si_stime = cputime_to_clock_t(cputime_add(tsk->stime,
-				tsk->signal->stime));
+	info.si_utime = cputime_to_clock_t(tsk->utime + tsk->signal->utime);
+	info.si_stime = cputime_to_clock_t(tsk->stime + tsk->signal->stime);
 
 	info.si_status = tsk->exit_code & 0x7f;
 	if (tsk->exit_code & 0x80)
@@ -1994,8 +1992,6 @@ static bool do_signal_stop(int signr)
 		 */
 		if (!(sig->flags & SIGNAL_STOP_STOPPED))
 			sig->group_exit_code = signr;
-		else
-			WARN_ON_ONCE(!current->ptrace);
 
 		sig->group_stop_count = 0;
 
@@ -2359,8 +2355,15 @@ void exit_signals(struct task_struct *tsk)
 	int group_stop = 0;
 	sigset_t unblocked;
 
+	/*
+	 * @tsk is about to have PF_EXITING set - lock out users which
+	 * expect stable threadgroup.
+	 */
+	threadgroup_change_begin(tsk);
+
 	if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
 		tsk->flags |= PF_EXITING;
+		threadgroup_change_end(tsk);
 		return;
 	}
 
@@ -2370,6 +2373,9 @@ void exit_signals(struct task_struct *tsk)
 	 * see wants_signal(), do_signal_stop().
 	 */
 	tsk->flags |= PF_EXITING;
+
+	threadgroup_change_end(tsk);
+
 	if (!signal_pending(tsk))
 		goto out;