[PATCH 1/4] de_thread: use change_pid() rather than detach_pid/attach_pid

[Oleg Nesterov <oleg@redhat.com>]

de_thread() can use change_pid() instead of detach + attach.
This looks better and this ensures that, say, next_thread()
can never see a task with ->pid == NULL.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
---
 fs/exec.c |    3 +--
 1 files changed, 1 insertions(+), 2 deletions(-)

diff --git a/fs/exec.c b/fs/exec.c
index 6430195..00eaba7 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -945,9 +945,8 @@ static int de_thread(struct task_struct *tsk)
 		 * Note: The old leader also uses this pid until release_task
 		 *       is called.  Odd but simple and correct.
 		 */
-		detach_pid(tsk, PIDTYPE_PID);
 		tsk->pid = leader->pid;
-		attach_pid(tsk, PIDTYPE_PID,  task_pid(leader));
+		change_pid(tsk, PIDTYPE_PID, task_pid(leader));
 		transfer_pid(leader, tsk, PIDTYPE_PGID);
 		transfer_pid(leader, tsk, PIDTYPE_SID);
 
-- 
1.5.5.1