Re: [PATCH 2/2] y2038: Convert gai_suspend to support 64 bit time

[Alistair Francis <alistair23@gmail.com>]

On Tue, Dec 1, 2020 at 1:45 AM Lukasz Majewski <lukma@denx.de> wrote:
>
> This change uses (in gai_misc.h):
> - __futex_abstimed_wait64 (instead of futex_reltimed_wait)
> - __futex_abstimed_wait_cancellable64
>         (instead of futex_reltimed_wait_cancellable)
>         from ./sysdeps/nptl/futex-helpers.h
>
> The gai_suspend() accepts relative timeout, which then is converted to
> absolute one.
>
> The i686-gnu port (HURD) do not define DONT_NEED_GAI_MISC_COND and as it
> doesn't (yet) support 64 bit time it uses not converted
> pthread_cond_timedwait().
>
> The __gai_suspend() is supposed to be run on ports with __TIMESIZE !=64 and
> __WORDSIZE==32. It internally utilizes __gai_suspend_time64() and hence the
> conversion from 32 bit struct timespec to 64 bit one is required.
>
> For ports supporting 64 bit time the __gai_suspend_time64() will be used
> either via alias (to __gai_suspend when __TIMESIZE==64) or redirection
> (when -D_TIME_BITS=64 is passed).
>
> Build tests:
> ./src/scripts/build-many-glibcs.py glibcs

Reviewed-by: Alistair Francis <alistair.francis@wdc.com>

Alistair

> ---
>  include/netdb.h         |  7 +++++
>  resolv/gai_suspend.c    | 61 ++++++++++++++++++++++++-----------------
>  sysdeps/nptl/gai_misc.h | 11 +++++---
>  3 files changed, 50 insertions(+), 29 deletions(-)
>
> diff --git a/include/netdb.h b/include/netdb.h
> index 49d63c1338..645b85dc62 100644
> --- a/include/netdb.h
> +++ b/include/netdb.h
> @@ -194,6 +194,13 @@ extern int ruserpass (const char *host, const char **aname,
>                       const char **apass);
>  libc_hidden_proto (ruserpass)
>
> +# if __TIMESIZE == 64
> +#  define __gai_suspend_time64 __gai_suspend
> +# else
> +extern int __gai_suspend_time64 (const struct gaicb *const list[], int ent,
> +                                 const struct __timespec64 *timeout);
> +libanl_hidden_proto (__gai_suspend_time64)
> +# endif
>
>  /* The following definition has been removed from the public header
>     since we don't want people to use them.  */
> diff --git a/resolv/gai_suspend.c b/resolv/gai_suspend.c
> index 734f9b4500..d75abeb7e3 100644
> --- a/resolv/gai_suspend.c
> +++ b/resolv/gai_suspend.c
> @@ -24,10 +24,9 @@
>
>  #include <gai_misc.h>
>
> -
>  int
> -gai_suspend (const struct gaicb *const list[], int ent,
> -            const struct timespec *timeout)
> +__gai_suspend_time64 (const struct gaicb *const list[], int ent,
> +                      const struct __timespec64 *timeout)
>  {
>    struct waitlist waitlist[ent];
>    struct requestlist *requestlist[ent];
> @@ -63,6 +62,19 @@ gai_suspend (const struct gaicb *const list[], int ent,
>           }
>        }
>
> +  struct __timespec64 ts;
> +  if (timeout != NULL)
> +    {
> +      __clock_gettime64 (CLOCK_MONOTONIC, &ts);
> +      ts.tv_sec += timeout->tv_sec;
> +      ts.tv_nsec += timeout->tv_nsec;
> +      if (ts.tv_nsec >= 1000000000)
> +       {
> +         ts.tv_nsec -= 1000000000;
> +         ts.tv_sec++;
> +       }
> +    }
> +
>    if (none)
>      {
>        if (cnt < ent)
> @@ -83,29 +95,11 @@ gai_suspend (const struct gaicb *const list[], int ent,
>
>  #ifdef DONT_NEED_GAI_MISC_COND
>        result = 0;
> -      GAI_MISC_WAIT (result, cntr, timeout, 1);
> +      GAI_MISC_WAIT (result, cntr, timeout == NULL ? NULL : &ts, 1);
>  #else
> -      if (timeout == NULL)
> -       result = pthread_cond_wait (&cond, &__gai_requests_mutex);
> -      else
> -       {
> -         /* We have to convert the relative timeout value into an
> -            absolute time value with pthread_cond_timedwait expects.  */
> -         struct timespec now;
> -         struct timespec abstime;
> -
> -          __clock_gettime (CLOCK_REALTIME, &now);
> -         abstime.tv_nsec = timeout->tv_nsec + now.tv_nsec;
> -         abstime.tv_sec = timeout->tv_sec + now.tv_sec;
> -         if (abstime.tv_nsec >= 1000000000)
> -           {
> -             abstime.tv_nsec -= 1000000000;
> -             abstime.tv_sec += 1;
> -           }
> -
> -         result = pthread_cond_timedwait (&cond, &__gai_requests_mutex,
> -                                          &abstime);
> -       }
> +      struct timespec ts32 = valid_timespec64_to_timespec (ts);
> +      result = pthread_cond_timedwait (&cond, &__gai_requests_mutex,
> +                                       timeout == NULL ? NULL : &ts32);
>  #endif
>
>        /* Now remove the entry in the waiting list for all requests
> @@ -155,3 +149,20 @@ gai_suspend (const struct gaicb *const list[], int ent,
>
>    return result;
>  }
> +
> +#if __TIMESIZE != 64
> +libanl_hidden_def (__gai_suspend_time64)
> +
> +int
> +__gai_suspend (const struct gaicb *const list[], int ent,
> +              const struct timespec *timeout)
> +{
> +  struct __timespec64 ts64;
> +
> +  if (timeout != NULL)
> +    ts64 = valid_timespec_to_timespec64 (*timeout);
> +
> +  return __gai_suspend_time64 (list, ent, timeout != NULL ? &ts64 : NULL);
> +}
> +#endif
> +weak_alias (__gai_suspend, gai_suspend)
> diff --git a/sysdeps/nptl/gai_misc.h b/sysdeps/nptl/gai_misc.h
> index c1d5e2e6f0..c72a863974 100644
> --- a/sysdeps/nptl/gai_misc.h
> +++ b/sysdeps/nptl/gai_misc.h
> @@ -46,11 +46,12 @@
>         do                                                                    \
>           {                                                                   \
>             if (cancel)                                                       \
> -             status = futex_reltimed_wait_cancelable (                       \
> -               (unsigned int *) futexaddr, oldval, timeout, FUTEX_PRIVATE);  \
> +             status = __futex_abstimed_wait_cancelable64 (                   \
> +               (unsigned int *) futexaddr, oldval, CLOCK_MONOTONIC, timeout, \
> +               FUTEX_PRIVATE);                                               \
>             else                                                              \
> -             status = futex_reltimed_wait ((unsigned int *) futexaddr,       \
> -               oldval, timeout, FUTEX_PRIVATE);                              \
> +             status = __futex_abstimed_wait64 ((unsigned int *) futexaddr,   \
> +               oldval, CLOCK_REALTIME, timeout, FUTEX_PRIVATE);              \
>             if (status != EAGAIN)                                             \
>               break;                                                          \
>                                                                               \
> @@ -62,6 +63,8 @@
>           result = EINTR;                                                     \
>         else if (status == ETIMEDOUT)                                         \
>           result = EAGAIN;                                                    \
> +       else if (status == EOVERFLOW)                                         \
> +         result = EOVERFLOW;                                                 \
>         else                                                                  \
>           assert (status == 0 || status == EAGAIN);                           \
>                                                                               \
> --
> 2.20.1
>