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.
WARNING: multiple messages have this Message-ID (diff)
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: 26+ 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 11:26 ` Florian Weimer 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 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 2019-09-23 21:27 ` Eric W. Biederman 2019-09-24 19:10 ` Michael Kerrisk (man-pages)
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