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Date:   Wed, 27 Apr 2022 17:20:18 +0200
From:   Oleg Nesterov <oleg@redhat.com>
To:     "Eric W. Biederman" <ebiederm@xmission.com>
Cc:     linux-kernel@vger.kernel.org, rjw@rjwysocki.net, mingo@kernel.org,
        vincent.guittot@linaro.org, dietmar.eggemann@arm.com,
        rostedt@goodmis.org, mgorman@suse.de, bigeasy@linutronix.de,
        Will Deacon <will@kernel.org>, tj@kernel.org,
        linux-pm@vger.kernel.org, Peter Zijlstra <peterz@infradead.org>,
        Richard Weinberger <richard@nod.at>,
        Anton Ivanov <anton.ivanov@cambridgegreys.com>,
        Johannes Berg <johannes@sipsolutions.net>,
        linux-um@lists.infradead.org, Chris Zankel <chris@zankel.net>,
        Max Filippov <jcmvbkbc@gmail.com>,
        inux-xtensa@linux-xtensa.org, Kees Cook <keescook@chromium.org>,
        Jann Horn <jannh@google.com>
Subject: Re: [PATCH 8/9] ptrace: Use siglock instead of tasklist_lock in
 ptrace_check_attach
Message-ID: <20220427152016.GF17421@redhat.com>
References: <878rrrh32q.fsf_-_@email.froward.int.ebiederm.org>
 <20220426225211.308418-8-ebiederm@xmission.com>
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On 04/26, Eric W. Biederman wrote:
>
> +	if (lock_task_sighand(child, &flags)) {
> +		if (child->ptrace && child->parent == current) {
> +			WARN_ON(READ_ONCE(child->__state) == __TASK_TRACED);
> +			/*
> +			 * child->sighand can't be NULL, release_task()
> +			 * does ptrace_unlink() before __exit_signal().
> +			 */
> +			if (ignore_state || ptrace_freeze_traced(child))
> +				ret = 0;

The comment above is no longer relevant, it should be removed.

Oleg.