Re: [RFC v3 05/23] sysdeps/timespec_get: Use clock_gettime64 if avaliable

[Florian Weimer <fweimer at redhat dot com>]

* Alistair Francis:

> +#if __WORDSIZE == 32
> +int
> +__timespec_get (struct timespec *ts, int base)
> +{
> +   int ret;
> +
> +#ifdef __NR_clock_gettime64
> +  struct __timespec64 ts64;
> +  ret = INTERNAL_VSYSCALL (clock_gettime64, err, 2, CLOCK_REALTIME, &ts64);
> +
> +  ts->tv_sec = ts64.tv_sec;
> +  ts->tv_nsec = ts64.tv_nsec;
> +
> +  if (! in_time_t_range (ts->tv_sec))
> +    {
> +      __set_errno (EOVERFLOW);
> +      return -1;
> +    }
> +#endif
> +
> +#ifndef __ASSUME_TIME64_SYSCALLS
> +  ret = INTERNAL_VSYSCALL (clock_gettime, err, 2, CLOCK_REALTIME, ts);
> +#endif

I don't think this is right.  I think you need to cache clock_gettime64
support somewhere and avoid trying to call the non-existing system call
again and again.  And the second system call will overwrite the results
of the first.

Thanks,
Florian