Kill some obsolete sub-thread-ptrace stuff (24728448) · Commits · 戴 / test

There is a couple of subtle checks which were needed to handle ptracing from the same thread group. This was deprecated a long ago, imho this code just complicates the understanding. And, the "->parent->signal->flags & SIGNAL_GROUP_EXIT" check in exit_notify() is not right. SIGNAL_GROUP_EXIT can mean exec(), not exit_group(). This means ptracer can lose a ptraced zombie on exec(). Minor problem, but still the bug. Signed-off-by:

Oleg Nesterov <oleg@tv-sign.ru> Acked-by:

Roland McGrath <roland@redhat.com> Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

kernel/exit.c

+2 −6

Original line number	Diff line number	Diff line
		@@ -826,9 +826,7 @@ static void exit_notify(struct task_struct *tsk)
		* If our self_exec id doesn't match our parent_exec_id then
		* we have changed execution domain as these two values started
		* the same after a fork.
		*
		*/

		if (tsk->exit_signal != SIGCHLD && tsk->exit_signal != -1 &&
		( tsk->parent_exec_id != t->self_exec_id \|\|
		tsk->self_exec_id != tsk->parent_exec_id)
		@@ -848,9 +846,7 @@ static void exit_notify(struct task_struct *tsk)
		}

		state = EXIT_ZOMBIE;
		if (tsk->exit_signal == -1 &&
		(likely(tsk->ptrace == 0) \|\|
		unlikely(tsk->parent->signal->flags & SIGNAL_GROUP_EXIT)))
		if (tsk->exit_signal == -1 && likely(!tsk->ptrace))
		state = EXIT_DEAD;
		tsk->exit_state = state;

kernel/signal.c

+0 −4

Original line number	Diff line number	Diff line
		@@ -1561,10 +1561,6 @@ static inline int may_ptrace_stop(void)
		(current->ptrace & PT_ATTACHED)))
		return 0;

		if (unlikely(current->signal == current->parent->signal) &&
		unlikely(current->signal->flags & SIGNAL_GROUP_EXIT))
		return 0;

		/*
		* Are we in the middle of do_coredump?
		* If so and our tracer is also part of the coredump stopping

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