__ptrace_detach: avoid task_detached(), check do_notify_parent()
__ptrace_detach() relies on the current obscure behaviour of
do_notify_parent(tsk) which changes tsk->exit_signal if this child
should be silently reaped. That is why we check task_detached(), it
is true if the task is sub-thread, or it is the group_leader but
its exit_signal was changed by do_notify_parent().
This is confusing, change the code to rely on !thread_group_leader()
or the value returned by do_notify_parent().
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Tejun Heo <tj@kernel.org>
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index e18966c..66a28bd 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -370,25 +370,28 @@
*/
static bool __ptrace_detach(struct task_struct *tracer, struct task_struct *p)
{
+ bool dead;
+
__ptrace_unlink(p);
- if (p->exit_state == EXIT_ZOMBIE) {
- if (!task_detached(p) && thread_group_empty(p)) {
- if (!same_thread_group(p->real_parent, tracer))
- do_notify_parent(p, p->exit_signal);
- else if (ignoring_children(tracer->sighand)) {
- __wake_up_parent(p, tracer);
- p->exit_signal = -1;
- }
- }
- if (task_detached(p)) {
- /* Mark it as in the process of being reaped. */
- p->exit_state = EXIT_DEAD;
- return true;
+ if (p->exit_state != EXIT_ZOMBIE)
+ return false;
+
+ dead = !thread_group_leader(p);
+
+ if (!dead && thread_group_empty(p)) {
+ if (!same_thread_group(p->real_parent, tracer))
+ dead = do_notify_parent(p, p->exit_signal);
+ else if (ignoring_children(tracer->sighand)) {
+ __wake_up_parent(p, tracer);
+ p->exit_signal = -1;
+ dead = true;
}
}
-
- return false;
+ /* Mark it as in the process of being reaped. */
+ if (dead)
+ p->exit_state = EXIT_DEAD;
+ return dead;
}
static int ptrace_detach(struct task_struct *child, unsigned int data)