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From: Daniel Colascione <dancol@google.com>
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>,
	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 11:39:53 -0800	[thread overview]
Message-ID: <CAKOZuethLLUEf-ZFVpm7u1msyYUJ1ArP2vemMUzrct7K0sv_WA@mail.gmail.com> (raw)
In-Reply-To: <20181119193128.hv7z4j52ajrue2jr@brauner.io>

Yep. That's also what I was talking about, FWIW.

On Mon, Nov 19, 2018 at 11:31 AM, Christian Brauner
<christian@brauner.io> wrote:
> 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
>>

  reply	other threads:[~2018-11-19 19:39 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
2018-11-19 19:39           ` Daniel Colascione [this message]
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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