On Thursday 08 November 2007 03:07, Andrew Morton wrote:
> > On Thu, 8 Nov 2007 12:53:57 +1100 Paul Mackerras <[email protected]> wrote:
> > Andrew Morton writes:
> >
> > > Given all this stuff, the return value from sys_times() doesn't seem a
> > > particularly useful or reliable kernel interface.
> >
> > I think the best thing would be to ignore any error from copy_to_user
> > and always return the number of clock ticks. We should call
> > force_successful_syscall_return, and glibc on x86 should be taught not
> > to interpret negative values as an error.
>
> Changing glibc might be hard ;)
>
> > POSIX doesn't require us to return an EFAULT error if the buf argument
> > is bogus. If userspace does supply a bogus buf pointer, then either
> > it will dereference it itself and get a segfault, or it won't
> > dereference it, in which case it obviously didn't care about the
> > values we tried to put there.
> >
> > If we try to return an error under some circumstances, then there is
> > at least one 32-bit value for the number of ticks that will cause
> > confusion. We can either change that value (or values) to some other
> > value, which seems pretty bogus, or we can just decide not to return
> > any errors. The latter seems to me to have no significant downside
> > and to be the simplest solution to the problem.
>
> "the latter" is what my protopatch does isn't it? It wraps at 0x7fffffff.
> It appears that glibc treats all of 0x80000000-0xffffffff as an error.
The best solution is to change the kernel to never return an error
and to change glibc to never treat return as an error.
--
vda
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