[PATCH v2] y2038: nptl: Convert pthread_{clock|timed}join_np to support 64 bit time

Adhemerval Zanella adhemerval.zanella@linaro.org
Thu Jul 23 20:43:17 GMT 2020



On 22/07/2020 04:37, Lukasz Majewski wrote:
> The pthread_clockjoin_np and pthread_timedjoin_np have been converted to
> support 64 bit time.
> 
> This change introduces new futex_timed_wait_cancel64 function in
> ./sysdeps/nptl/futex-internal.h, which uses futex_time64 where possible
> and tries to replace low-level preprocessor macros from
> lowlevellock-futex.h
> The pthread_{timed|clock}join_np only accept absolute time. Moreover,
> there is no need to check for NULL passed as *abstime pointer as
> clockwait_tid() always passes struct __timespec64.
> 
> For systems with __TIMESIZE != 64 && __WORDSIZE == 32:
> - Conversions between 64 bit time to 32 bit are necessary
> - Redirection to __pthread_{clock|timed}join_np64 will provide support
>   for 64 bit time
> 
> Build tests:
> ./src/scripts/build-many-glibcs.py glibcs
> 
> Run-time tests:
> - Run specific tests on ARM/x86 32bit systems (qemu):
>   https://github.com/lmajewski/meta-y2038 and run tests:
>   https://github.com/lmajewski/y2038-tests/commits/master
> 
> Above tests were performed with Y2038 redirection applied as well as without
> to test the proper usage of both __pthread_{timed|clock}join_np64 and
> __pthread_{timed|clock}join_np.
> 
> ---
> Changes for v2:
> - Update the commit message

Some comments below regarding the futex-internal additions, the other
changes looks ok.

> ---
>  nptl/pthreadP.h               | 16 +++++++++++++++-
>  nptl/pthread_clockjoin.c      | 19 ++++++++++++++++---
>  nptl/pthread_join_common.c    | 19 +++++++++++--------
>  nptl/pthread_timedjoin.c      | 18 ++++++++++++++++--
>  sysdeps/nptl/futex-internal.h | 31 +++++++++++++++++++++++++++++++
>  5 files changed, 89 insertions(+), 14 deletions(-)
> 
> diff --git a/nptl/pthreadP.h b/nptl/pthreadP.h
> index 6f94d6be31..99713c8447 100644
> --- a/nptl/pthreadP.h
> +++ b/nptl/pthreadP.h
> @@ -458,6 +458,20 @@ extern int __pthread_cond_init (pthread_cond_t *cond,
>  libc_hidden_proto (__pthread_cond_init)
>  extern int __pthread_cond_signal (pthread_cond_t *cond);
>  extern int __pthread_cond_wait (pthread_cond_t *cond, pthread_mutex_t *mutex);
> +
> +#if __TIMESIZE == 64
> +# define __pthread_clockjoin_np64 __pthread_clockjoin_np
> +# define __pthread_timedjoin_np64 __pthread_timedjoin_np
> +#else
> +extern int __pthread_clockjoin_np64 (pthread_t threadid, void **thread_return,
> +                                     clockid_t clockid,
> +                                     const struct __timespec64 *abstime);
> +libc_hidden_proto (__pthread_clockjoin_np64)
> +extern int __pthread_timedjoin_np64 (pthread_t threadid, void **thread_return,
> +                                     const struct __timespec64 *abstime);
> +libc_hidden_proto (__pthread_timedjoin_np64)
> +#endif
> +
>  extern int __pthread_cond_timedwait (pthread_cond_t *cond,
>  				     pthread_mutex_t *mutex,
>  				     const struct timespec *abstime);
> @@ -488,7 +502,7 @@ extern int __pthread_enable_asynccancel (void) attribute_hidden;
>  extern void __pthread_disable_asynccancel (int oldtype) attribute_hidden;
>  extern void __pthread_testcancel (void);
>  extern int __pthread_clockjoin_ex (pthread_t, void **, clockid_t,
> -				   const struct timespec *, bool)
> +				   const struct __timespec64 *, bool)
>    attribute_hidden;
>  extern int __pthread_sigmask (int, const sigset_t *, sigset_t *);
>  libc_hidden_proto (__pthread_sigmask);

Ok.

> diff --git a/nptl/pthread_clockjoin.c b/nptl/pthread_clockjoin.c
> index a3e7f37e3b..3cd780f688 100644
> --- a/nptl/pthread_clockjoin.c
> +++ b/nptl/pthread_clockjoin.c
> @@ -16,14 +16,27 @@
>     License along with the GNU C Library; if not, see
>     <http://www.gnu.org/licenses/>.  */
>  
> +#include <time.h>
>  #include "pthreadP.h"
>  
>  int
> -__pthread_clockjoin_np (pthread_t threadid, void **thread_return,
> -			clockid_t clockid,
> -			const struct timespec *abstime)
> +__pthread_clockjoin_np64 (pthread_t threadid, void **thread_return,
> +                          clockid_t clockid, const struct __timespec64 *abstime)
>  {
>    return __pthread_clockjoin_ex (threadid, thread_return,
>                                   clockid, abstime, true);
>  }
> +
> +#if __TIMESIZE != 64
> +libc_hidden_def (__pthread_clockjoin_np64)
> +
> +int
> +__pthread_clockjoin_np (pthread_t threadid, void **thread_return,
> +                        clockid_t clockid, const struct timespec *abstime)
> +{
> +  struct __timespec64 ts64 = valid_timespec_to_timespec64 (*abstime);
> +
> +  return __pthread_clockjoin_np64 (threadid, thread_return, clockid, &ts64);
> +}
> +#endif
>  weak_alias (__pthread_clockjoin_np, pthread_clockjoin_np)

Ok.

> diff --git a/nptl/pthread_join_common.c b/nptl/pthread_join_common.c
> index a96ceafde4..67d8e2b780 100644
> --- a/nptl/pthread_join_common.c
> +++ b/nptl/pthread_join_common.c
> @@ -20,6 +20,7 @@
>  #include <atomic.h>
>  #include <stap-probe.h>
>  #include <time.h>
> +#include <futex-internal.h>
>  
>  static void
>  cleanup (void *arg)
> @@ -37,9 +38,11 @@ cleanup (void *arg)
>     afterwards.  The kernel up to version 3.16.3 does not use the private futex
>     operations for futex wake-up when the clone terminates.  */
>  static int
> -clockwait_tid (pid_t *tidp, clockid_t clockid, const struct timespec *abstime)
> +clockwait_tid (pid_t *tidp, clockid_t clockid,
> +               const struct __timespec64 *abstime)
>  {
>    pid_t tid;
> +  int ret;
>  
>    if (! valid_nanoseconds (abstime->tv_nsec))
>      return EINVAL;
> @@ -47,11 +50,11 @@ clockwait_tid (pid_t *tidp, clockid_t clockid, const struct timespec *abstime)
>    /* Repeat until thread terminated.  */
>    while ((tid = *tidp) != 0)
>      {
> -      struct timespec rt;
> +      struct __timespec64 rt;
>  
>        /* Get the current time. This can only fail if clockid is
>           invalid. */
> -      if (__glibc_unlikely (__clock_gettime (clockid, &rt)))
> +      if (__glibc_unlikely (__clock_gettime64 (clockid, &rt)))
>          return EINVAL;
>  
>        /* Compute relative timeout.  */
> @@ -70,9 +73,9 @@ clockwait_tid (pid_t *tidp, clockid_t clockid, const struct timespec *abstime)
>        /* If *tidp == tid, wait until thread terminates or the wait times out.
>           The kernel up to version 3.16.3 does not use the private futex
>           operations for futex wake-up when the clone terminates.  */
> -      if (lll_futex_timed_wait_cancel (tidp, tid, &rt, LLL_SHARED)
> -	  == -ETIMEDOUT)
> -        return ETIMEDOUT;
> +      ret = futex_timed_wait_cancel64 (tidp, tid, &rt, LLL_SHARED);
> +      if (ret == -ETIMEDOUT || ret == -EOVERFLOW)
> +        return -ret;
>      }
>  
>    return 0;
> @@ -80,8 +83,8 @@ clockwait_tid (pid_t *tidp, clockid_t clockid, const struct timespec *abstime)
>  
>  int
>  __pthread_clockjoin_ex (pthread_t threadid, void **thread_return,
> -			clockid_t clockid,
> -			const struct timespec *abstime, bool block)
> +                        clockid_t clockid,
> +                        const struct __timespec64 *abstime, bool block)
>  {
>    struct pthread *pd = (struct pthread *) threadid;
>  

Ok, this is an internal interface so we free to change it.

> diff --git a/nptl/pthread_timedjoin.c b/nptl/pthread_timedjoin.c
> index dd7038dcf7..6164ae7060 100644
> --- a/nptl/pthread_timedjoin.c
> +++ b/nptl/pthread_timedjoin.c
> @@ -16,13 +16,27 @@
>     License along with the GNU C Library; if not, see
>     <https://www.gnu.org/licenses/>.  */
>  
> +#include <time.h>
>  #include "pthreadP.h"
>  
>  int
> -__pthread_timedjoin_np (pthread_t threadid, void **thread_return,
> -			const struct timespec *abstime)
> +__pthread_timedjoin_np64 (pthread_t threadid, void **thread_return,
> +                          const struct __timespec64 *abstime)
>  {
>    return __pthread_clockjoin_ex (threadid, thread_return,
>                                   CLOCK_REALTIME, abstime, true);
>  }
> +
> +#if __TIMESIZE != 64
> +libc_hidden_def (__pthread_timedjoin_np64)
> +
> +int
> +__pthread_timedjoin_np (pthread_t threadid, void **thread_return,
> +                        const struct timespec *abstime)
> +{
> +  struct __timespec64 ts64 = valid_timespec_to_timespec64 (*abstime);
> +
> +  return __pthread_timedjoin_np64 (threadid, thread_return, &ts64);
> +}
> +#endif
>  weak_alias (__pthread_timedjoin_np, pthread_timedjoin_np)

Ok.

> diff --git a/sysdeps/nptl/futex-internal.h b/sysdeps/nptl/futex-internal.h
> index d622122ddc..e0a539ae9e 100644
> --- a/sysdeps/nptl/futex-internal.h
> +++ b/sysdeps/nptl/futex-internal.h
> @@ -467,4 +467,35 @@ futex_unlock_pi (unsigned int *futex_word, int private)
>      }
>  }
>  
> +#ifndef __NR_futex_time64
> +# define __NR_futex_time64 __NR_futex
> +#endif
> +
> +static __always_inline int
> +futex_timed_wait_cancel64 (pid_t *tidp,  pid_t tid,
> +                           struct __timespec64 *timeout, int private)

Should we set the timeout as 'const'? Afaik the kernel won't modify its value.

> +{
> +  int oldtype = CANCEL_ASYNC ();
> +  long int ret = INTERNAL_SYSCALL (futex_time64, 4, tidp,
> +                                   __lll_private_flag (FUTEX_WAIT, private),
> +                                   tid, timeout);

We have INTERNAL_SYSCALL_CALL, although I don't have a strong preference
here.  It allows to not need to handle the reset state on early return,
as done in EOVERFLOW below.  In any case use INTERNAL_SYSCALL_CALL.

> +#ifndef __ASSUME_TIME64_SYSCALLS
> +  if (ret == -ENOSYS)
> +    {
> +      struct timespec ts32;
> +      if (! in_time_t_range (timeout->tv_sec))
> +        {
> +          CANCEL_RESET (oldtype);
> +          return -EOVERFLOW;
> +	}
> +      ts32 = valid_timespec64_to_timespec (*timeout);
> +
> +      ret = INTERNAL_SYSCALL (futex, 4, tidp,
> +                              __lll_private_flag (FUTEX_WAIT, private),
> +                              tid, &ts32);

Use INTERNAL_SYCALL_CALL here.

> +    }
> +#endif
> +    CANCEL_RESET (oldtype);
> +    return ret;
> +}
>  #endif  /* futex-internal.h */
> 

I think we should follow the other futex_ routines regarding the possible
return values, i.e, document the possible return values and explicit fail
with futex_fatal_error for non expected ones.


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