pids: __set_special_pids: use change_pid() helper

Use change_pid() instead of detach_pid() + attach_pid() in
__set_special_pids().

This way task_session() is not NULL in between.

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc:  "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 4 deletions

diff --git a/kernel/exit.c b/kernel/exit.c
index 0da2921b1e7f..d3ad54677f9c 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -334,13 +334,11 @@ void __set_special_pids(struct pid *pid)
         pid_t nr = pid_nr(pid);
 
         if (task_session(curr) != pid) {
-                detach_pid(curr, PIDTYPE_SID);
-                attach_pid(curr, PIDTYPE_SID, pid);
+                change_pid(curr, PIDTYPE_SID, pid);
                 set_task_session(curr, nr);
         }
         if (task_pgrp(curr) != pid) {
-                detach_pid(curr, PIDTYPE_PGID);
-                attach_pid(curr, PIDTYPE_PGID, pid);
+                change_pid(curr, PIDTYPE_PGID, pid);
                 set_task_pgrp(curr, nr);
         }
 }