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Date:   Wed, 24 Jul 2019 19:52:08 +0200
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Subject: Re: [PATCH 2/5] pidfd: add pidfd_wait()
To:     Linus Torvalds <torvalds@linux-foundation.org>
CC:     Linux List Kernel Mailing <linux-kernel@vger.kernel.org>,
        Oleg Nesterov <oleg@redhat.com>, Arnd Bergmann <arnd@arndb.de>,
        "Eric W. Biederman" <ebiederm@xmission.com>,
        Kees Cook <keescook@chromium.org>,
        Joel Fernandes <joel@joelfernandes.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Tejun Heo <tj@kernel.org>, David Howells <dhowells@redhat.com>,
        Jann Horn <jannh@google.com>,
        Andrew Lutomirski <luto@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Aleksa Sarai <cyphar@cyphar.com>,
        Al Viro <viro@zeniv.linux.org.uk>,
        Android Kernel Team <kernel-team@android.com>,
        Linux API <linux-api@vger.kernel.org>
From:   Christian Brauner <christian@brauner.io>
Message-ID: <D9BD06E2-576A-4627-8047-0AA86B6CCDA9@brauner.io>
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On July 24, 2019 7:50:49 PM GMT+02:00, Christian Brauner <christian@brauner=
=2Eio> wrote:
>On July 24, 2019 7:45:38 PM GMT+02:00, Linus Torvalds
><torvalds@linux-foundation=2Eorg> wrote:
>>On Wed, Jul 24, 2019 at 7:47 AM Christian Brauner
>><christian@brauner=2Eio> wrote:
>>>
>>> This adds the pidfd_wait() syscall=2E
>>
>>I despise this patch=2E
>>
>>Why can't this just be a new P_PIDFD flag, and then use
>>"waitid(P_PIDFD, pidfd, =2E=2E=2E);"
>>
>>Yes, yes, yes, I realize that "pidfd" is of type "int", and waitid()
>>takes an argument of type pid_t, but it's the same type in the end,
>>and it does seem like the whole *point* of "waitid()" is that
>>"idtype_t idtype" which tells you what kind of ID you're passing it=2E
>>
>>               Linus
>
>Well in that case we could add P_PIDFD=2E
>But then I would like to _only_ enable it for waitid()=2E How's that
>sound?
>
>Christian

Ah, sorry, just saw that that's what you suggested=2E

Christian