From 57a059187d5ba5592e36c6f23d046bc37616f346 Mon Sep 17 00:00:00 2001
From: Oleg Nesterov <oleg@redhat.com>
Date: Wed, 10 Dec 2014 15:45:27 -0800
Subject: [PATCH] exit: reparent: cleanup the changing of ->parent
1. Cosmetic, but "if (t->parent == father)" looks a bit confusing.
We need to change t->parent if and only if t is not traced.
2. If we actually want this BUG_ON() to ensure that parent/ptrace
match each other, then we should also take ptrace_reparented()
case into account too.
3. Change this code to use for_each_thread() instead of deprecated
while_each_thread().
[dan.carpenter@oracle.com: silence a bogus static checker warning]
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Aaron Tomlin <atomlin@redhat.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>,
Cc: Sterling Alexander <stalexan@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Roland McGrath <roland@hack.frob.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
kernel/exit.c | 13 +++++--------
1 file changed, 5 insertions(+), 8 deletions(-)
diff --git a/kernel/exit.c b/kernel/exit.c
index 0272305bf855c..464971e6923eb 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -557,7 +557,7 @@ static void reparent_leader(struct task_struct *father, struct task_struct *p,
static void forget_original_parent(struct task_struct *father)
{
- struct task_struct *p, *n, *reaper;
+ struct task_struct *p, *t, *n, *reaper;
LIST_HEAD(dead_children);
write_lock_irq(&tasklist_lock);
@@ -569,18 +569,15 @@ static void forget_original_parent(struct task_struct *father)
reaper = find_new_reaper(father);
list_for_each_entry_safe(p, n, &father->children, sibling) {
- struct task_struct *t = p;
-
- do {
+ for_each_thread(p, t) {
t->real_parent = reaper;
- if (t->parent == father) {
- BUG_ON(t->ptrace);
+ BUG_ON((!t->ptrace) != (t->parent == father));
+ if (likely(!t->ptrace))
t->parent = t->real_parent;
- }
if (t->pdeath_signal)
group_send_sig_info(t->pdeath_signal,
SEND_SIG_NOINFO, t);
- } while_each_thread(p, t);
+ }
reparent_leader(father, p, &dead_children);
}
write_unlock_irq(&tasklist_lock);
--
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