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From:   Florian Weimer <fw@deneb.enyo.de>
To:     "Michael Kerrisk \(man-pages\)" <mtk.manpages@gmail.com>
Cc:     Christian Brauner <christian@brauner.io>,
        Jann Horn <jannh@google.com>,
        Daniel Colascione <dancol@google.com>,
        "Eric W. Biederman" <ebiederm@xmission.com>,
        Joel Fernandes <joel@joelfernandes.org>,
        Linux API <linux-api@vger.kernel.org>,
        lkml <linux-kernel@vger.kernel.org>,
        linux-man <linux-man@vger.kernel.org>,
        Oleg Nesterov <oleg@redhat.com>
Subject: Re: For review: pidfd_open(2) manual page
References: <90399dee-53d8-a82c-3871-9ec8f94601ce@gmail.com>
        <87tv939td6.fsf@mid.deneb.enyo.de>
        <63566f1f-667d-50ca-ae85-784924d09af4@gmail.com>
Date:   Mon, 23 Sep 2019 22:41:19 +0200
In-Reply-To: <63566f1f-667d-50ca-ae85-784924d09af4@gmail.com> (Michael
        Kerrisk's message of "Mon, 23 Sep 2019 22:20:31 +0200")
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* Michael Kerrisk:

>>>        static
>>>        int pidfd_open(pid_t pid, unsigned int flags)
>>>        {
>>>            return syscall(__NR_pidfd_open, pid, flags);
>>>        }
>> 
>> Please call this function something else (not pidfd_open), so that the
>> example continues to work if glibc provides the system call wrapper.
>
> I figured that if the syscall does get added to glibc, then I would
> modify the example. In the meantime, this does seem the most natural
> way of doing things, since the example then uses the real syscall
> name as it would be used if there were a wrapper function.

The problem is that programs do this as well, so they fail to build
once they are built on a newer glibc version.

> But, this leads to the question: what do you think the likelihood
> is that this system call will land in glibc?

Quite likely.  It's easy enough to document, there are no P&C issues,
and it doesn't need any new types.

pidfd_send_signal is slightly more difficult because we probably need
to add rt_sigqueueinfo first, for consistency.