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authorOleg Nesterov <oleg@redhat.com>2014-12-10 15:55:08 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2014-12-10 17:41:17 -0800
commit175aed3f8d38b87d3287bb765c794205f2b511de (patch)
tree81365f68bb26d9c14cc6059990ca0deb6b6af941 /kernel/exit.c
parent3750ef979cfa1296630aa9f23e265c1bd721498a (diff)
downloadlinux-sh-175aed3f8d38b87d3287bb765c794205f2b511de.tar.gz
exit: reparent: document the ->has_child_subreaper checks
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>
Diffstat (limited to 'kernel/exit.c')
-rw-r--r--kernel/exit.c14
1 files changed, 6 insertions, 8 deletions
diff --git a/kernel/exit.c b/kernel/exit.c
index a4204aaba8a2..576949ce5665 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -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;