From: Christian Brauner <christian@brauner.io>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Daniel Colascione <dancol@google.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>,
linux-man <linux-man@vger.kernel.org>,
Kees Cook <keescook@chromium.org>
Subject: Re: [PATCH v1 2/2] signal: add procfd_signal() syscall
Date: Mon, 19 Nov 2018 20:31:31 +0100 [thread overview]
Message-ID: <20181119193128.hv7z4j52ajrue2jr@brauner.io> (raw)
In-Reply-To: <87o9ak28nl.fsf@xmission.com>
On Mon, Nov 19, 2018 at 01:02:06PM -0600, Eric W. Biederman wrote:
> Christian Brauner <christian@brauner.io> writes:
>
> > On Mon, Nov 19, 2018 at 07:59:24AM -0800, Daniel Colascione wrote:
> >> You never addressed my comment on the previous patch about your use of
> >
> > Sorry, that thread exploded so quickly that I might have missed it.
> >
> >> private_data here. Why can't you use the struct pid reference that's
> >> already in the inode?
> >
> > If that's what people prefer we can probably use that. There was
> > precedent for stashing away such data in fs/proc/base.c already for
> > various other things including user namespaces and struct mm so I
> > followed this model. A prior version of my patch (I didn't send out) did
> > retrive the inode via proc_pid() in .open() took an additional reference
> > via get_pid() and dropped it in .release(). Do we prefer that?
>
> If you are using proc/<pid>/ directories as your file descriptors, you
> don't need to add an open or a release method at all. The existing file
> descriptors hold a reference to the inode which holds a reference the
> the struct pid.
>
> The only time you need to get a reference is when you need a task
> and kill_pid_info already performs that work for you.
Oh, I see what you and Andy are saying now. Sweet, that means we can
trim down the patch even more. Less code, less headache.
Thanks!
>
> So using proc_pid is all you need to do to get the pid from the existing
> file descriptors.
>
> Eric
>
next prev parent reply other threads:[~2018-11-19 19:31 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-19 10:32 [PATCH v1 0/2] proc: allow signaling processes via file descriptors Christian Brauner
2018-11-19 10:32 ` [PATCH v1 1/2] proc: get process file descriptor from /proc/<pid> Christian Brauner
2018-11-19 15:32 ` Andy Lutomirski
2018-11-19 18:20 ` Christian Brauner
2018-11-19 10:32 ` [PATCH v1 2/2] signal: add procfd_signal() syscall Christian Brauner
2018-11-19 15:45 ` Andy Lutomirski
2018-11-19 15:57 ` Daniel Colascione
2018-11-19 18:39 ` Christian Brauner
2018-11-19 15:59 ` Daniel Colascione
2018-11-19 18:29 ` Christian Brauner
2018-11-19 19:02 ` Eric W. Biederman
2018-11-19 19:31 ` Christian Brauner [this message]
2018-11-19 19:39 ` Daniel Colascione
2018-11-19 17:10 ` Eugene Syromiatnikov
2018-11-19 18:23 ` Christian Brauner
2018-11-19 17:14 ` Eugene Syromiatnikov
2018-11-19 20:28 ` Aleksa Sarai
2018-11-19 20:55 ` Christian Brauner
2018-11-19 21:13 ` Christian Brauner
2018-11-19 21:18 ` Aleksa Sarai
2018-11-19 21:20 ` Christian Brauner
2018-11-19 21:21 ` Christian Brauner
2018-11-19 21:25 ` Aleksa Sarai
2018-11-19 21:26 ` Daniel Colascione
2018-11-19 21:36 ` Aleksa Sarai
2018-11-19 21:37 ` Christian Brauner
2018-11-19 21:41 ` Daniel Colascione
2018-11-20 4:59 ` Eric W. Biederman
2018-11-20 10:31 ` Christian Brauner
2018-11-21 21:39 ` Serge E. Hallyn
2018-11-19 21:23 ` Aleksa Sarai
2018-11-22 7:41 ` Serge E. Hallyn
2018-11-19 22:39 ` Tycho Andersen
2018-11-19 22:49 ` Daniel Colascione
2018-11-19 23:07 ` Tycho Andersen
2018-11-20 0:27 ` Andy Lutomirski
2018-11-20 0:32 ` Christian Brauner
2018-11-20 0:34 ` Andy Lutomirski
2018-11-20 0:49 ` Daniel Colascione
2018-11-22 7:48 ` Serge E. Hallyn
2018-11-19 23:35 ` kbuild test robot
2018-11-19 23:37 ` kbuild test robot
2018-11-19 23:45 ` Christian Brauner
2018-11-28 21:45 ` Joey Pabalinas
2018-11-28 22:05 ` Christian Brauner
2018-11-28 23:02 ` Joey Pabalinas
2018-11-19 10:32 ` [PATCH] procfd_signal.2: document procfd_signal syscall Christian Brauner
2018-11-20 13:29 ` Michael Kerrisk (man-pages)
2018-11-28 20:59 ` Florian Weimer
2018-11-28 21:12 ` Christian Brauner
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