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exit: reparent: cleanup the changing of ->parent

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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>
This commit is contained in:
Oleg Nesterov 2014-12-10 15:45:27 -08:00 committed by Linus Torvalds
parent dc2fd4b009
commit 57a059187d
1 changed files with 5 additions and 8 deletions
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13
kernel/exit.c
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@ -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) 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); LIST_HEAD(dead_children);
write_lock_irq(&tasklist_lock); write_lock_irq(&tasklist_lock);
@ -569,18 +569,15 @@ static void forget_original_parent(struct task_struct *father)
reaper = find_new_reaper(father); reaper = find_new_reaper(father);
list_for_each_entry_safe(p, n, &father->children, sibling) { list_for_each_entry_safe(p, n, &father->children, sibling) {
struct task_struct *t = p; for_each_thread(p, t) {
do {
t->real_parent = reaper; t->real_parent = reaper;
if (t->parent == father) { BUG_ON((!t->ptrace) != (t->parent == father));
BUG_ON(t->ptrace); if (likely(!t->ptrace))
t->parent = t->real_parent; t->parent = t->real_parent;
}
if (t->pdeath_signal) if (t->pdeath_signal)
group_send_sig_info(t->pdeath_signal, group_send_sig_info(t->pdeath_signal,
SEND_SIG_NOINFO, t); SEND_SIG_NOINFO, t);
} while_each_thread(p, t); }
reparent_leader(father, p, &dead_children); reparent_leader(father, p, &dead_children);
} }
write_unlock_irq(&tasklist_lock); write_unlock_irq(&tasklist_lock);