Re: [RFC v3 04/23] sysdeps/clock_gettime: Use clock_gettime64 if avaliable

[Florian Weimer <fweimer at redhat dot com>]

* Alistair Francis:

> diff --git a/nptl/pthread_mutex_timedlock.c b/nptl/pthread_mutex_timedlock.c
> index 52c258e33d..8d9cae7d87 100644
> --- a/nptl/pthread_mutex_timedlock.c
> +++ b/nptl/pthread_mutex_timedlock.c
> @@ -402,10 +402,17 @@ __pthread_mutex_clocklock_common (pthread_mutex_t *mutex,
>  		    /* Delay the thread until the timeout is reached.
>  		       Then return ETIMEDOUT.  */
>  		    struct timespec reltime;
> +#ifdef __NR_clock_gettime64
> +		    struct __timespec64 now;
> +
> +		    INTERNAL_SYSCALL (clock_gettime64, __err, 2, CLOCK_REALTIME,
> +				      &now);
> +#else
>  		    struct timespec now;
>  
>  		    INTERNAL_SYSCALL (clock_gettime, __err, 2, clockid,
>  				      &now);
> +#endif
>  		    reltime.tv_sec = abstime->tv_sec - now.tv_sec;
>  		    reltime.tv_nsec = abstime->tv_nsec - now.tv_nsec;
>  		    if (reltime.tv_nsec < 0)

I believe this needs to be updated for correctness (truncation of
tv_sec) if ever ported to architectures where __nanosleep_nocancel takes
a 32-bit time_t argument.  I don't know what our plans are regarding to
that.

If you had

#define __NR_clock_gettime64  __NR_clock_gettime

in <sysdep.h>, you wouldn't need this change.

> diff --git a/sysdeps/unix/sysv/linux/clock_gettime.c b/sysdeps/unix/sysv/linux/clock_gettime.c
> index 5fc47fb7dc..4832069c34 100644
> --- a/sysdeps/unix/sysv/linux/clock_gettime.c
> +++ b/sysdeps/unix/sysv/linux/clock_gettime.c
> @@ -27,10 +27,40 @@
>  #include <sysdep-vdso.h>
>  
>  /* Get current value of CLOCK and store it in TP.  */
> +
> +#if __WORDSIZE == 32
> +int
> +__clock_gettime (clockid_t clock_id, struct timespec *tp)
> +{
> +   int ret;
> +
> +#ifdef __NR_clock_gettime64
> +  struct __timespec64 tp64;
> +  ret = INLINE_VSYSCALL (clock_gettime64, 2, clock_id, &tp64);
> +
> +  tp->tv_sec = tp64.tv_sec;
> +  tp->tv_nsec = tp64.tv_nsec;
> +
> +  if (! in_time_t_range (tp->tv_sec))
> +    {
> +      __set_errno (EOVERFLOW);
> +      return -1;
> +    }
> +#endif
> +
> +#ifndef __ASSUME_TIME64_SYSCALLS
> +  ret = INLINE_VSYSCALL (clock_gettime, 2, clock_id, tp);
> +#endif
> +
> +  return ret;
> +}

I think this has the same problems as the timespec_get patch.

Thanks,
Florian