Re: [PATCH v5 13/14] epoll: implement epoll_create2() syscall

[Roman Penyaev]

On 2019-06-24 18:14, Arnd Bergmann wrote:
> On Mon, Jun 24, 2019 at 4:42 PM Roman Penyaev <rpenyaev@xxxxxxx> wrote:
> > epoll_create2() is needed to accept EPOLL_USERPOLL flags
> > and size, i.e. this patch wires up polling from userspace.
>
> Can you explain in the patch description more what it's needed for?

Sure. Will update on next iteration.

> The man page only states that "Since Linux 2.6.8, the size argument
> is ignored", so your description above does not explain why you need
> to add the size argument back.
>
> > diff --git a/arch/alpha/kernel/syscalls/syscall.tbl 
> > b/arch/alpha/kernel/syscalls/syscall.tbl
> > index 1db9bbcfb84e..a1d7b695063d 100644
> > --- a/arch/alpha/kernel/syscalls/syscall.tbl
> > +++ b/arch/alpha/kernel/syscalls/syscall.tbl
> > @@ -474,3 +474,5 @@
> >  542    common  fsmount                         sys_fsmount
> >  543    common  fspick                          sys_fspick
> >  544    common  pidfd_open                      sys_pidfd_open
> > +# 546  common  clone3                  sys_clone3
> > +547    common  epoll_create2                   sys_epoll_create2
> > diff --git a/arch/arm/tools/syscall.tbl b/arch/arm/tools/syscall.tbl
> > index ff45d8807cb8..1497f3c87d54 100644
> > --- a/arch/arm/tools/syscall.tbl
> > +++ b/arch/arm/tools/syscall.tbl
> > @@ -449,3 +449,4 @@
> >  433    common  fspick                          sys_fspick
> >  434    common  pidfd_open                      sys_pidfd_open
> >  436    common  clone3                          sys_clone3
> > +437    common  epoll_create2                   sys_epoll_create2
>
> The table changes all look correct and complete, provided we
> don't get another patch picking the same number.

Good.  I had doubts, because on some archs there is a gap,
(sys_clone3 was missing).  So I left a placeholder, so
can be uncommented when sys_clone3 is implemented.

--
Roman