exit: reparent: s/while_each_thread/for_each_thread/ in find_new_reaper()
exit: reparent: s/while_each_thread/for_each_thread/ in find_new_reaper()

Change find_new_reaper() to use for_each_thread() instead of deprecated
while_each_thread().  We do not bother to check "thread != father" in the
1st loop, we can rely on PF_EXITING check.

Note: this means the minor behavioural change: for_each_thread() starts
from the group leader.  But this should be fine, nobody should make any
assumption about do_wait(__WNOTHREAD) when it comes to reparented tasks.
And this can avoid the pointless reparenting to a short-living thread
While zombie leaders are not that common.

Signed-off-by: Oleg Nesterov <20b70f0af00562e63758b9ee42012ecc96c58590@redhat.com>
Cc: Aaron Tomlin <4ed61b0b61ab8b39dcdee4eca4730f0b305b3047@redhat.com>
Cc: "Eric W. Biederman" <8a741aa8cbd77ebc4a56ddb528ce9fd15d42f034@xmission.com>
Cc: Kay Sievers <e9264147b413746293e539868c8edff71715e1e3@vrfy.org>
Cc: Lennart Poettering <9bb3d23d041c1d0454e62fec951f9aa4dfa2787f@poettering.net>
Cc: Sterling Alexander <9eb90039aece32f9874377e394d636d5e7a331fe@redhat.com>
Signed-off-by: Andrew Morton <5c1e68b099950c134891f0b6e179498a8ebe9cf9@linux-foundation.org>
Signed-off-by: Linus Torvalds <69652caca27c8b940640ad396ab71f93cacec34f@linux-foundation.org>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs