times(2) sys call bug?

[Joakim Tjernlund]

On Fri, 2008-11-21 at 10:50 +0100, Gabriel Paubert wrote:
> On Fri, Nov 21, 2008 at 08:03:06PM +1100, Paul Mackerras wrote:
> > Gabriel Paubert writes:
> > 
> > > On Fri, Nov 21, 2008 at 10:52:14AM +1100, Paul Mackerras wrote:
> > > > Joakim Tjernlund writes:
> > > > 
> > > > > This little hack changes the kernel sys call handling in an crude
> > > > > way and then it works. Apperently the kernel thinks is an error if the
> > > > > syscall returns a value between -_LAST_ERRNO and -1.
> > > > 
> > > > Try this patch and let me if it fixes it.  If it does I'll push it
> > > > upstream.
> > > 
> > > With your patch, you won't get EFAULT if you pass a bad
> > > address, but a constant, time independent value, unless
> > > I miss something. 
> > 
> > I think you are missing something, namely that I put the call to
> > force_successful_syscall_return() AFTER the return -EFAULT.
> > 
> 
> Indeed, it may be time to update the syscall documentation, saying
> that you need to clear errno before the syscall and check errno
> and not the return value since -1 is valid. 

And perhaps mention that times(NULL) never returns an error.
And that times() is broken in 2.6.27 and earlier and needs the
workaround posted earlier.

 Jocke