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exit: reparent: document the ->has_child_subreaper checks

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Swap the "init_task" and same_thread_group() checks.  This way it is more
simple to document these checks and we can remove the link to the previous
discussion on lkml.

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>
This commit is contained in:
Oleg Nesterov 2014-12-10 15:55:08 -08:00 committed by Linus Torvalds
parent 3750ef979c
commit 175aed3f8d
1 changed files with 6 additions and 8 deletions
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14
kernel/exit.c
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@ -495,18 +495,16 @@ static struct task_struct *find_new_reaper(struct task_struct *father)
if (father->signal->has_child_subreaper) {
struct task_struct *reaper;
/*
* Find the first ancestor marked as child_subreaper.
* Note that the code below checks same_thread_group(reaper,
* pid_ns->child_reaper). This is what we need to DTRT in a
* PID namespace. However we still need the check above, see
* http://marc.info/?l=linux-kernel&m=131385460420380
* Find the first ->is_child_subreaper ancestor in our pid_ns.
* We start from father to ensure we can not look into another
* namespace, this is safe because all its threads are dead.
*/
for (reaper = father;
reaper != &init_task;
!same_thread_group(reaper, pid_ns->child_reaper);
reaper = reaper->real_parent) {
if (same_thread_group(reaper, pid_ns->child_reaper))
/* call_usermodehelper() descendants need this check */
if (reaper == &init_task)
break;
if (!reaper->signal->is_child_subreaper)
continue;