Isolate some explicit usage of task->tgid

With pid namespaces this field is now dangerous to use explicitly, so hide
it behind the helpers.

Also the pid and pgrp fields o task_struct and signal_struct are to be
deprecated.  Unfortunately this patch cannot be sent right now as this
leads to tons of warnings, so start isolating them, and deprecate later.

Actually the p->tgid == pid has to be changed to has_group_leader_pid(),
but Oleg pointed out that in case of posix cpu timers this is the same, and
thread_group_leader() is more preferable.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Acked-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 2 deletions

diff --git a/fs/exec.c b/fs/exec.c
index 007d0d814bf0..2c942e2d14ea 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -841,8 +841,8 @@ static int de_thread(struct task_struct *tsk)
                  */
                 tsk->start_time = leader->start_time;
 
-                BUG_ON(leader->tgid != tsk->tgid);
-                BUG_ON(tsk->pid == tsk->tgid);
+                BUG_ON(!same_thread_group(leader, tsk));
+                BUG_ON(has_group_leader_pid(tsk));
                 /*
                  * An exec() starts a new thread group with the
                  * TGID of the previous thread group. Rehash the