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 <oleg@redhat.com>
Cc: Aaron Tomlin <atomlin@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Kay Sievers <kay@vrfy.org>
Cc: Lennart Poettering <lennart@poettering.net>
Cc: Sterling Alexander <stalexan@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 3 insertions, 5 deletions

diff --git a/kernel/exit.c b/kernel/exit.c
index 9babd47a36e2..a4204aaba8a2 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -473,8 +473,7 @@ static struct task_struct *find_new_reaper(struct task_struct *father)
         struct pid_namespace *pid_ns = task_active_pid_ns(father);
         struct task_struct *thread;
 
-        thread = father;
-        while_each_thread(father, thread) {
+        for_each_thread(father, thread) {
                 if (thread->flags & PF_EXITING)
                         continue;
                 if (unlikely(pid_ns->child_reaper == father))
@@ -511,11 +510,10 @@ static struct task_struct *find_new_reaper(struct task_struct *father)
                                 break;
                         if (!reaper->signal->is_child_subreaper)
                                 continue;
-                        thread = reaper;
-                        do {
+                        for_each_thread(reaper, thread) {
                                 if (!(thread->flags & PF_EXITING))
                                         return thread;
-                        } while_each_thread(reaper, thread);
+                        }
                 }
         }