Re: [PATCH 03/20] asm-generic: Drop getrlimit and setrlimit syscalls from default list

[Yury Norov <ynorov@caviumnetworks.com>]

On Tue, Jun 20, 2017 at 04:20:43PM +0200, Arnd Bergmann wrote:
> On Tue, Jun 20, 2017 at 3:37 PM, Yury Norov <ynorov@caviumnetworks.com> wrote:
> > On Mon, Jun 19, 2017 at 11:10:23PM +0100, James Hogan wrote:
> >> On Mon, Jun 19, 2017 at 11:58:41PM +0200, Arnd Bergmann wrote:
> >> > On Mon, Jun 19, 2017 at 11:42 PM, James Hogan <james.hogan@imgtec.com> wrote:
> >> > > On Mon, Jun 19, 2017 at 06:49:46PM +0300, Yury Norov wrote:
> >> > > Subject: [PATCH] Deprecate stat syscalls superseded by statx
> >> > >
> >> > > Various stat system calls can now be implemented as userland wrappers
> >> > > around the new statx system call, so allow them to be removed from the
> >> > > kernel by default for new architectures / ABIs.
> >> > >
> >> > > This involves adding __ARCH_WANT_SYSCALL_UNXSTAT to each existing
> >> > > architecture, which enables the relevant stat system calls in the
> >> > > generic system call list (if used). It also conditionally defines the
> >> > > syscalls in fs/stat.c and struct stat / struct stat64 in
> >> > > asm-generic/stat.h.
> >> > >
> >> > > Signed-off-by: James Hogan <james.hogan@imgtec.com>
> >> > > Cc: David Howells <dhowells@redhat.com>
> >> > > Cc: Alexander Viro <viro@zeniv.linux.org.uk>
> >> > > Cc: Arnd Bergmann <arnd@arndb.de>
> >> > > Cc: linux-fsdevel@vger.kernel.org
> >> > > Cc: linux-arch@vger.kernel.org
> >> > > Cc: linux-api@vger.kernel.org
> >> > > Cc: linux-kernel@vger.kernel.org
> >> >
> >> > Good idea:
> >> >
> >> > Acked-by:  Arnd Bergmann <arnd@arndb.de>
> >> > > +/* statx deprecates the un-extended stat syscalls which use struct stat[64] */
> >> > > +#ifdef __ARCH_WANT_SYSCALL_UNXSTAT
> >> >
> >> > I'm glad you explain what 'UNXSTAT' means here, since I would not
> >> > have otherwise guessed it, but I also can't think of anything more
> >> > intuitive.
> >>
> >> Yeh, I renamed that several times while playing around with this :-).
> >>
> >> The stat syscalls remind me a bit of the Vicar of Dibley episode where
> >> the new road named "New Road" necessitates the renaming of the existing
> >> "New Road" to "Quite Old Road" and "Quite Old Road" to "Really Quite Old
> >> Road" and "Old Road" to "Very Old Road"!
> >
> > (Add Palmer Dabbelt <palmer@dabbelt.com>)
> >
> > The stat syscalls are full of hacks, and we have to pull that hacks
> > even to new architectures to deal with stat. So I'll be happy to drop
> > it in arm64/ilp32. But it means that I need some time to integrate
> > your patch and fix glibc accordingly. And it also means that we need
> > round 9 for ilp32... :(
> >
> > Arnd, once before you told that generic unistd has some duplications
> > and legacy syscalls, and one day we'll have to deal with it. Do you
> > have the list or something on it?
> 
> No, I'd have to do some research for that.
> 
> > I would also notice riscv people and welcome to the discussion.
> >
> > As there is more than 1 arch that goes to be added to linux soon,
> > maybe it's better to upstream my ans James' patches separately
> > from other ilp32 patches? Arnd?
> 
> Do you mean upstream those two patches slightly later? That's
> fine with me, I don't care much whether the old new stat is part
> of the syscall table for arm64-ilp32 or not, I'd leave that up to
> you, depending on whether you want to do the rework or not.
 
I mean that if we want to deprecate rlimit and stat syscalls for
architectures that are under development now, it's better to upstream
patches that actually deprecate it as early as possible. 

> I suppose the arm64-ilp32 could benefit from not having to support
> the old arm32 stat structure, but doing the new syscalls based on
> statx could delay the glibc port some more, as there are some open
> questions about how that would best be integrated.

OK. Let's leave things as is. But then I don't see any reason to
add unxstat patch to ilp32 series if ilp32 will not disable it.

Yury