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List:       glibc-alpha
Subject:    Re: [PATCH v6 3/3] y2038: linux: Provide __mq_timedreceive_time64 implementation
From:       Adhemerval Zanella via Libc-alpha <libc-alpha () sourceware ! org>
Date:       2020-03-31 14:58:28
Message-ID: 1e5d660e-bb02-128d-1185-fa1568a3ddc6 () linaro ! org
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On 31/03/2020 05:35, Lukasz Majewski wrote:
> This patch provides new __mq_timedreceive_time64 explicit 64 bit function for
> receiving messages with absolute timeout.
> Moreover, a 32 bit version - __mq_timedreceive has been refactored to
> internally use __mq_timedreceive_time64.
> 
> The __mq_timedreceive is now supposed to be used on systems still supporting 32
> bit time (__TIMESIZE != 64) - hence the necessary conversion to 64 bit struct
> __timespec64 from struct timespec.
> 
> The new mq_timedsend_time64 syscall available from Linux 5.1+ has been used,
> when applicable.
> 
> As this wrapper function is also used internally in the glibc, to e.g. provide
> mq_receive implementation, an explicit check for abs_timeout being NULL has been
> added due to conversions between struct timespec and struct __timespec64.
> Before this change the Linux kernel handled this NULL pointer.
> 
> 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
> 
> Linux kernel, headers and minimal kernel version for glibc build test matrix:
> - Linux v5.1 (with mq_timedreceive_time64) and glibc built with v5.1 as
>   minimal kernel version (--enable-kernel="5.1.0")
>   The __ASSUME_TIME64_SYSCALLS flag defined.
> 
> - Linux v5.1 and default minimal kernel version
>   The __ASSUME_TIME64_SYSCALLS not defined, but kernel supports
>   mq_timedreceive_time64 syscall.
> 
> - Linux v4.19 (no mq_timedreceive_time64 support) with default minimal kernel
>   version for contemporary glibc (3.2.0)
>   This kernel doesn't support mq_timedreceive_time64 syscall, so the fallback to
>   mq_timedreceive is tested.
> 
> Above tests were performed with Y2038 redirection applied as well as without
> (so the __TIMESIZE != 64 execution path is checked as well).
> 
> Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>


Still LGTM, thanks.

> 
> ---
> Changes for v6:
> - Replace implicit check for abs_timeout with an explicit one -
>   abs_timeout != NULL
> - Reformat function (__mq_timedreceive_time64) declaration
> 
> Changes for v5:
> - None
> 
> Changes for v4:
> - None
> 
> Changes for v3:
> - None
> 
> Changes for v2:
> - Fix indentation in __mq_timedreceive function
> ---
>  include/mqueue.h                          |  8 ++++
>  sysdeps/unix/sysv/linux/mq_timedreceive.c | 51 +++++++++++++++++++++--
>  2 files changed, 55 insertions(+), 4 deletions(-)
> 
> diff --git a/include/mqueue.h b/include/mqueue.h
> index 32e6570529..98e4596c22 100644
> --- a/include/mqueue.h
> +++ b/include/mqueue.h
> @@ -13,10 +13,18 @@ hidden_proto (mq_setattr)
>  #include <struct___timespec64.h>
>  #if __TIMESIZE == 64
>  # define __mq_timedsend_time64 __mq_timedsend
> +# define __mq_timedreceive_time64 __mq_timedreceive
>  #else
>  extern int __mq_timedsend_time64 (mqd_t mqdes, const char *msg_ptr,
>                                    size_t msg_len, unsigned int msg_prio,
>                                    const struct __timespec64 *abs_timeout);
>  librt_hidden_proto (__mq_timedsend_time64)
> +extern ssize_t __mq_timedreceive_time64 (mqd_t mqdes,
> +                                         char *__restrict msg_ptr,
> +                                         size_t msg_len,
> +                                         unsigned int *__restrict msg_prio,
> +                                         const struct __timespec64 *__restrict
> +                                         abs_timeout);
> +librt_hidden_proto (__mq_timedreceive_time64)
>  #endif
>  #endif
> diff --git a/sysdeps/unix/sysv/linux/mq_timedreceive.c b/sysdeps/unix/sysv/linux/mq_timedreceive.c
> index 73a1d63e41..728a63d1ec 100644
> --- a/sysdeps/unix/sysv/linux/mq_timedreceive.c
> +++ b/sysdeps/unix/sysv/linux/mq_timedreceive.c
> @@ -22,13 +22,56 @@
>  /* Receive the oldest from highest priority messages in message queue
>     MQDES, stop waiting if ABS_TIMEOUT expires.  */
>  ssize_t
> -__mq_timedreceive (mqd_t mqdes, char *__restrict msg_ptr, size_t msg_len,
> -		   unsigned int *__restrict msg_prio,
> -		   const struct timespec *__restrict abs_timeout)
> +__mq_timedreceive_time64 (mqd_t mqdes, char *__restrict msg_ptr, size_t msg_len,
> +                          unsigned int *__restrict msg_prio,
> +                          const struct __timespec64 *__restrict abs_timeout)
>  {
> +#ifdef __ASSUME_TIME64_SYSCALLS
> +# ifndef __NR_mq_timedreceive_time64
> +#  define __NR_mq_timedreceive_time64 __NR_mq_timedreceive
> +# endif
> +  return SYSCALL_CANCEL (mq_timedreceive_time64, mqdes, msg_ptr, msg_len,
> +                         msg_prio, abs_timeout);
> +#else
> +  int ret = SYSCALL_CANCEL (mq_timedreceive_time64, mqdes, msg_ptr, msg_len,
> +                            msg_prio, abs_timeout);
> +  if (ret == 0 || errno != ENOSYS)
> +    return ret;
> +
> +  struct timespec ts32;
> +  if (abs_timeout != NULL)
> +    {
> +      if (! in_time_t_range (abs_timeout->tv_sec))
> +        {
> +          __set_errno (EOVERFLOW);
> +          return -1;
> +        }
> +
> +      ts32 = valid_timespec64_to_timespec (*abs_timeout);
> +    }
> +
>    return SYSCALL_CANCEL (mq_timedreceive, mqdes, msg_ptr, msg_len, msg_prio,
> -			 abs_timeout);
> +                         abs_timeout != NULL ? &ts32 : NULL);
> +#endif
> +}
> +
> +#if __TIMESIZE != 64
> +librt_hidden_def (__mq_timedreceive_time64)
> +
> +ssize_t
> +__mq_timedreceive (mqd_t mqdes, char *__restrict msg_ptr, size_t msg_len,
> +                   unsigned int *__restrict msg_prio,
> +                   const struct timespec *__restrict abs_timeout)
> +{
> +  struct __timespec64 ts64;
> +  if (abs_timeout != NULL)
> +    ts64 = valid_timespec_to_timespec64 (*abs_timeout);
> +
> +  return __mq_timedreceive_time64 (mqdes, msg_ptr, msg_len, msg_prio,
> +                                   abs_timeout != NULL ? &ts64 : NULL);
>  }
> +#endif
> +
>  hidden_def (__mq_timedreceive)
>  weak_alias (__mq_timedreceive, mq_timedreceive)
>  hidden_weak (mq_timedreceive)
> 
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