linux-kernel - Re: [PATCH 3/4] ptrace: reintroduce __ptrace_detach() as a callee of ptrace

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Message-Id: <20090205012334.9E60FFC381@magilla.sf.frob.com>
Date:	Wed,  4 Feb 2009 17:23:34 -0800 (PST)
From:	Roland McGrath <roland@...hat.com>
To:	Oleg Nesterov <oleg@...hat.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Jerome Marchand <jmarchan@...hat.com>,
	Denys Vlasenko <dvlasenk@...hat.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/4] ptrace: reintroduce __ptrace_detach() as a callee of
	ptrace_exit()

> No functional changes, preparation for the next patch.
> 
> Move the "should we release this child" logic into the separate handler,
> __ptrace_detach().

My inclination is to use bool in new code for true/false return values,
but I don't really care.

Please canonicalize the comment formatting for your new comments.

The preserved comment no longer makes sense, there is no "dead list" in
that function.  Make it a coherent comment at the top that explains the
return value.  

Given its content, this function now better belongs in ptrace.c, I think.


Thanks,
Roland

=====

/*
 * Called with tasklist_lock held for writing.
 * Unlink a traced task, and clean it up if it was a traced zombie.
 * Return true if it needs to be reaped with release_task().
 * (We can't call release_task() here because we already hold tasklist_lock.)
 *
 * If it's a zombie, our attachedness prevented normal parent notification
 * or self-reaping.  Do notification now if it would have happened earlier.
 * If it should reap itself, return true.
 *
 * If it's our own child, there is no notification to do.
 * But if our normal children self-reap, then this child
 * was prevented by ptrace and we must reap it now.
 */
bool __ptrace_detach(struct task_struct *tracer, struct task_struct *p)
{
	__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))
				p->exit_signal = -1;
		}
		if (task_detached(p)) {
			/*
			 * Mark it as in the process of being reaped.
			 */
			p->exit_state = EXIT_DEAD;
			return true;
		}
	}

	return false;
}
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