Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
MIME-Version: 1.0
In-Reply-To: <20181118111751.6142-1-christian@brauner.io>
References: <20181118111751.6142-1-christian@brauner.io>
From:   Daniel Colascione <dancol@google.com>
Date:   Sun, 18 Nov 2018 08:03:15 -0800
Message-ID: <CAKOZuet2E8fwwx1kQftjCGJ2w5T4LS38yfr1kbMUK_PG3ffNHg@mail.gmail.com>
Subject: Re: [PATCH] proc: allow killing processes via file descriptors
To:     Christian Brauner <christian@brauner.io>
Cc:     "Eric W. Biederman" <ebiederm@xmission.com>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        "Serge E. Hallyn" <serge@hallyn.com>, Jann Horn <jannh@google.com>,
        Andy Lutomirski <luto@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Oleg Nesterov <oleg@redhat.com>,
        Aleksa Sarai <cyphar@cyphar.com>,
        Al Viro <viro@zeniv.linux.org.uk>,
        Linux FS Devel <linux-fsdevel@vger.kernel.org>,
        Linux API <linux-api@vger.kernel.org>,
        Tim Murray <timmurray@google.com>,
        Kees Cook <keescook@chromium.org>
Content-Type: text/plain; charset="UTF-8"
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Sun, Nov 18, 2018 at 3:17 AM, Christian Brauner <christian@brauner.io> wrote:
> +static int proc_tgid_open(struct inode *inode, struct file *file)
> +{
> +       /* grab reference to struct pid */
> +       file->private_data = get_pid(proc_pid(inode));

Why grab another reference to the struct pid when the inode already has one?