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From:   Florian Weimer <fweimer@redhat.com>
To:     Daniel Colascione <dancol@google.com>
Cc:     Linus Torvalds <torvalds@linux-foundation.org>,
        Jonathan Kowalski <bl0pbl33p@gmail.com>,
        Aleksa Sarai <cyphar@cyphar.com>,
        Andy Lutomirski <luto@amacapital.net>,
        Christian Brauner <christian@brauner.io>,
        Jann Horn <jannh@google.com>,
        Andrew Lutomirski <luto@kernel.org>,
        David Howells <dhowells@redhat.com>,
        "Serge E. Hallyn" <serge@hallyn.com>,
        Linux API <linux-api@vger.kernel.org>,
        Linux List Kernel Mailing <linux-kernel@vger.kernel.org>,
        Arnd Bergmann <arnd@arndb.de>,
        "Eric W. Biederman" <ebiederm@xmission.com>,
        Konstantin Khlebnikov <khlebnikov@yandex-team.ru>,
        Kees Cook <keescook@chromium.org>,
        Alexey Dobriyan <adobriyan@gmail.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Michael Kerrisk-manpages <mtk.manpages@gmail.com>,
        "Dmitry V. Levin" <ldv@altlinux.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Oleg Nesterov <oleg@redhat.com>,
        Nagarathnam Muthusamy <nagarathnam.muthusamy@oracle.com>,
        Al Viro <viro@zeniv.linux.org.uk>,
        Joel Fernandes <joel@joelfernandes.org>
Subject: Re: [PATCH v2 0/5] pid: add pidfd_open()
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Date:   Tue, 02 Apr 2019 13:03:24 +0200
In-Reply-To: <CAKOZuet2QCoW1XMpTAzXS868PhF-gh14czFn4gwE4A=oX=Yr8w@mail.gmail.com>
        (Daniel Colascione's message of "Mon, 1 Apr 2019 09:45:22 -0700")
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* Daniel Colascione:

> But doesn't the CSIGNAL approach still require that libraries somehow
> coordinate which non-SIGCHLD signal they use? (Signal coordination a
> separate problem, unfortunately.)

There's already an allocation mechanism for realtime signals in glibc,
via __libc_allocate_rtsig.  I don't know what it is about: It's clearly
intended as an external interface, yet there isn't a declaration in any
installed header file.  ALSA has some optional code to use it, but I
don't think distributions compile ALSA in that way; it always uses SIGIO.

Thanks,
Florian