From: Florian Weimer <fw@deneb.enyo.de>
To: "Michael Kerrisk \(man-pages\)" <mtk.manpages@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>,
Christian Brauner <christian@brauner.io>,
Jann Horn <jannh@google.com>,
"Eric W. Biederman" <ebiederm@xmission.com>,
Daniel Colascione <dancol@google.com>,
Joel Fernandes <joel@joelfernandes.org>,
linux-man <linux-man@vger.kernel.org>,
Linux API <linux-api@vger.kernel.org>,
lkml <linux-kernel@vger.kernel.org>
Subject: Re: For review: pidfd_send_signal(2) manual page
Date: Mon, 23 Sep 2019 13:26:34 +0200 [thread overview]
Message-ID: <87pnjr9rth.fsf@mid.deneb.enyo.de> (raw)
In-Reply-To: <f21dbd73-5ef4-fb5b-003f-ff4fec34a1de@gmail.com> (Michael Kerrisk's message of "Mon, 23 Sep 2019 11:12:00 +0200")
* Michael Kerrisk:
> SYNOPSIS
> int pidfd_send_signal(int pidfd, int sig, siginfo_t info,
> unsigned int flags);
This probably should reference a header for siginfo_t.
> ESRCH The target process does not exist.
If the descriptor is valid, does this mean the process has been waited
for? Maybe this can be made more explicit.
> The pidfd_send_signal() system call allows the avoidance of race
> conditions that occur when using traditional interfaces (such as
> kill(2)) to signal a process. The problem is that the traditional
> interfaces specify the target process via a process ID (PID), with
> the result that the sender may accidentally send a signal to the
> wrong process if the originally intended target process has termi‐
> nated and its PID has been recycled for another process. By con‐
> trast, a PID file descriptor is a stable reference to a specific
> process; if that process terminates, then the file descriptor
> ceases to be valid and the caller of pidfd_send_signal() is
> informed of this fact via an ESRCH error.
It would be nice to explain somewhere how you can avoid the race using
a PID descriptor. Is there anything else besides CLONE_PIDFD?
> static
> int pidfd_send_signal(int pidfd, int sig, siginfo_t *info,
> unsigned int flags)
> {
> return syscall(__NR_pidfd_send_signal, pidfd, sig, info, flags);
> }
Please use a different function name. Thanks.
next prev parent reply other threads:[~2019-09-23 11:26 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-23 9:12 For review: pidfd_send_signal(2) manual page Michael Kerrisk (man-pages)
2019-09-23 11:26 ` Florian Weimer [this message]
2019-09-23 14:23 ` Christian Brauner
2019-09-24 19:44 ` Michael Kerrisk (man-pages)
2019-09-24 19:57 ` Christian Brauner
2019-09-24 20:07 ` Christian Brauner
2019-09-24 21:00 ` Michael Kerrisk (man-pages)
2019-09-24 21:08 ` Daniel Colascione
2019-09-25 13:46 ` Michael Kerrisk (man-pages)
2019-09-24 21:53 ` Christian Brauner
2019-09-25 13:46 ` Michael Kerrisk (man-pages)
2019-09-25 13:51 ` Florian Weimer
2019-09-25 14:02 ` Michael Kerrisk (man-pages)
2019-09-25 13:53 ` Christian Brauner
2019-09-25 14:29 ` Michael Kerrisk (man-pages)
2019-09-24 19:43 ` Michael Kerrisk (man-pages)
2019-09-25 1:48 ` Jann Horn
2019-09-23 11:31 ` Daniel Colascione
2019-09-24 19:42 ` Michael Kerrisk (man-pages)
2019-09-23 14:29 ` Christian Brauner
2019-09-23 20:27 ` Michael Kerrisk (man-pages)
2019-09-23 21:27 ` Eric W. Biederman
2019-09-24 19:10 ` Michael Kerrisk (man-pages)
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