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From:   Dmitry Safonov <0x7f454c46@gmail.com>
Date:   Mon, 29 Jul 2019 20:17:58 +0100
Message-ID: <CAJwJo6baR_w_sE8Qtr4Le9KTLWx0Qzi99qmoTm+6hd1j1UkmFA@mail.gmail.com>
Subject: Re: [PATCH 1/2] fork: extend clone3() to support CLONE_SET_TID
To:     Adrian Reber <areber@redhat.com>
Cc:     Christian Brauner <christian@brauner.io>,
        Eric Biederman <ebiederm@xmission.com>,
        Pavel Emelianov <xemul@virtuozzo.com>,
        Jann Horn <jannh@google.com>,
        open list <linux-kernel@vger.kernel.org>,
        Oleg Nesterov <oleg@redhat.com>,
        Andrei Vagin <avagin@gmail.com>,
        Mike Rapoport <rppt@linux.ibm.com>,
        Radostin Stoyanov <rstoyanov1@gmail.com>
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On Mon, 29 Jul 2019 at 20:12, Dmitry Safonov <0x7f454c46@gmail.com> wrote:
>
> On Mon, 29 Jul 2019 at 17:52, Adrian Reber <areber@redhat.com> wrote:
> [..]
> > --- a/include/uapi/linux/sched.h
> > +++ b/include/uapi/linux/sched.h
> > @@ -32,6 +32,7 @@
> >  #define CLONE_NEWPID           0x20000000      /* New pid namespace */
> >  #define CLONE_NEWNET           0x40000000      /* New network namespace */
> >  #define CLONE_IO               0x80000000      /* Clone io context */
> > +#define CLONE_SET_TID          0x100000000ULL  /* set if the desired TID is set in set_tid */
> >
> >  /*
> >   * Arguments for the clone3 syscall
> > @@ -45,6 +46,7 @@ struct clone_args {
> >         __aligned_u64 stack;
> >         __aligned_u64 stack_size;
> >         __aligned_u64 tls;
> > +       __aligned_u64 set_tid;
> >  };
> >
>
> I don't see a change to
> :    if (unlikely(size < sizeof(struct clone_args)))
> :        return -EINVAL;
>
> That seems backwards-incompatible, but I may miss some part..

On the other hand, clone3() was merged in v5.3 window, so probably,
it doesn't matter.

-- 
             Dmitry