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Date:   Wed, 9 Jul 2014 20:59:36 +0200
From:   Oleg Nesterov <oleg@redhat.com>
To:     Kees Cook <keescook@chromium.org>
Cc:     linux-kernel@vger.kernel.org,
        Andy Lutomirski <luto@amacapital.net>,
        "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com>,
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        linux-arch@vger.kernel.org, linux-security-module@vger.kernel.org
Subject: Re: [PATCH v9 09/11] seccomp: introduce writer locking
Message-ID: <20140709185936.GA6043@redhat.com>
References: <1403911380-27787-1-git-send-email-keescook@chromium.org> <1403911380-27787-10-git-send-email-keescook@chromium.org>
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On 06/27, Kees Cook wrote:
>
>  void put_seccomp_filter(struct task_struct *tsk)
>  {
> -	struct seccomp_filter *orig = tsk->seccomp.filter;
> +	struct seccomp_filter *orig = smp_load_acquire(&tsk->seccomp.filter);
>  	/* Clean up single-reference branches iteratively. */
>  	while (orig && atomic_dec_and_test(&orig->usage)) {

And this smp_load_acquire() looks unnecessary. atomic_dec_and_test()
is a barrier.

Oleg.