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Re: prlimit64: inconsistencies between kernel and userland
- From: Andreas Barth <aba at ayous dot org>
- To: Rich Felker <dalias at aerifal dot cx>
- Cc: "Joseph S. Myers" <joseph at codesourcery dot com>, David Miller <davem at davemloft dot net>, aurelien at aurel32 dot net, linux-mips at linux-mips dot org, libc-alpha at sourceware dot org
- Date: Tue, 5 Nov 2013 09:58:59 +0100
- Subject: Re: prlimit64: inconsistencies between kernel and userland
- Authentication-results: sourceware.org; auth=none
- References: <20130628133835 dot GA21839 at hall dot aurel32 dot net> <20131104213756 dot GD18700 at hall dot aurel32 dot net> <20131104 dot 194519 dot 1657797548878784116 dot davem at davemloft dot net> <Pine dot LNX dot 4 dot 64 dot 1311050058580 dot 9883 at digraph dot polyomino dot org dot uk> <20131105012203 dot GA24286 at brightrain dot aerifal dot cx>
* Rich Felker (dalias@aerifal.cx) [131105 02:22]:
> On Tue, Nov 05, 2013 at 01:04:45AM +0000, Joseph S. Myers wrote:
> > On Mon, 4 Nov 2013, David Miller wrote:
> >
> > > From: Aurelien Jarno <aurelien@aurel32.net>
> > > Date: Mon, 4 Nov 2013 22:37:56 +0100
> > >
> > > > Any news about this issue? It really starts to causes a lot of issues in
> > > > Debian. I have added a Cc: to libc people so that we can also hear their
> > > > opinion.
> > >
> > > I had the same exact problem on sparc several years ago, I simply fixed
> > > the glibc header value, it's the only way to fix this.
> > >
> > > Yes, that means you then have to recompile applications and libraries
> > > that reference this value.
> >
> > Surely you can create new symbol versions for getrlimit64 and setrlimit64,
> > with the old versions just using the 32-bit syscalls (or otherwise
> > translating between conventions, but using the 32-bit syscalls is the
> > simplest approach)? I see no need to break compatibility with existing
> > binaries.
> >
> > As I noted in
> > <https://sourceware.org/ml/libc-ports/2006-05/msg00020.html>, at that time
> > the value of RLIM64_INFINITY for o32/n32 was purely a glibc convention the
> > kernel didn't see at all. It's only with the use of newer syscalls that
> > this glibc convention is any sort of problem.
>
> Why not just make them convert any value >= 0x7fffffffffffffff to
> infinity before making the syscall? There's certainly no meaningful
> use for finite values in that range...
Or just replace 0x7fffffffffffffff by kernels infinity - and still
fixing glibc, because the same value as the kernel should be the right
answer long term.
Andi