From: Oleg Nesterov <oleg@tv-sign.ru>

Now that task_session() can't return a false NULL, check_kill_permission()
doesn't need tasklist_lock.

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 kernel/signal.c |    2 --
 1 file changed, 2 deletions(-)

diff -puN kernel/signal.c~signals-check_kill_permission-remove-tasklist_lock kernel/signal.c
--- a/kernel/signal.c~signals-check_kill_permission-remove-tasklist_lock
+++ a/kernel/signal.c
@@ -551,9 +551,7 @@ static int check_kill_permission(int sig
 	    !capable(CAP_KILL)) {
 		switch (sig) {
 		case SIGCONT:
-			read_lock(&tasklist_lock);
 			sid = task_session(t);
-			read_unlock(&tasklist_lock);
 			/*
 			 * We don't return the error if sid == NULL. The
 			 * task was unhashed, the caller must notice this.
_