Re: [PATCH V2] signal: Prevent exec() race

[Thomas Gleixner]

On Wed, Sep 02 2026 at 16:19, Oleg Nesterov wrote:
> This is subjective and mostly cosmetic, but what do you think
> about the alternative change below?
>
> I won't insist, but to me both the patch and resulting code look
> a bit simpler this way.

Yeah, though if we restructure the code then I rather prefer to get rid
of the gotos and also move the cgroup...end() part out of the sighand
lock held region to make that as short as possible.

void exit_signals(struct task_struct *tsk)
{
	LIST_HEAD(sigq_list);
	int group_stop = 0;

	/*
	 * @tsk is about to have PF_EXITING set - lock out users which
	 * expect a stable threadgroup.
	 */
	cgroup_threadgroup_change_begin(tsk);

	scoped_guard(spinlock_irq, &tsk->sighand->siglock) {
		tsk->flags |= PF_EXITING;

		sigqueue_dequeue_pending(&tsk->pending, &sigq_list);

		if (task_sigpending(tsk) && !thread_group_empty(tsk) &&
		    !(tsk->signal->flags & SIGNAL_GROUP_EXIT)) {
			sigset_t unblocked = tsk->blocked;

			signotset(&unblocked);
			retarget_shared_pending(tsk, &unblocked);

			if (unlikely(tsk->jobctl & JOBCTL_STOP_PENDING) &&
			    task_participate_group_stop(tsk))
				group_stop = CLD_STOPPED;
		}
	}

	cgroup_threadgroup_change_end(tsk);

	flush_sigqueue_list(&sigq_list);

	/*
	 * If group stop has completed, deliver the notification.  This
	 * should always go to the real parent of the group leader.
	 */
	if (unlikely(group_stop)) {
		read_lock(&tasklist_lock);
		do_notify_parent_cldstop(tsk, false, group_stop);
		read_unlock(&tasklist_lock);
	}
}