[PATCH] score: Document Futex Handler

[Joel Sherrill]

On Tue, Aug 31, 2021, 7:31 AM Sebastian Huber <
sebastian.huber at embedded-brains.de> wrote:

> Use EAGIN instead of EWOULDBLOCK to be in line with the Linux man page.
>

EAGAIN AND Linux man page for what?

These error numbers have the same values in Newlib.
> ---
>  cpukit/score/src/futex.c | 42 ++++++++++++++++++++++++++++++++++++++--
>  1 file changed, 40 insertions(+), 2 deletions(-)
>
> diff --git a/cpukit/score/src/futex.c b/cpukit/score/src/futex.c
> index b65a843704..f3a1ae3994 100644
> --- a/cpukit/score/src/futex.c
> +++ b/cpukit/score/src/futex.c
> @@ -1,11 +1,12 @@
>  /**
>   * @file
>   *
> - * @ingroup RTEMSScore
> + * @ingroup RTEMSScoreFutex
>   *
>   * @brief This source file contains the implementation of
>   *   _Futex_Wait() and _Futex_Wake().
>   */
> +
>  /*
>   * Copyright (c) 2015, 2016 embedded brains GmbH.  All rights reserved.
>   *
> @@ -20,6 +21,18 @@
>   * http://www.rtems.org/license/LICENSE.
>   */
>
> +/**
> + * @defgroup RTEMSScoreFutex Futex Handler
> + *
> + * @ingroup RTEMSScore
> + *
> + * @brief This group contains the Futex Handler implementation.
> + *
> + * The behaviour of the futex operations is defined by Linux, see also:
> + *
> + * https://man7.org/linux/man-pages/man2/futex.2.html
> + */
> +
>  #ifdef HAVE_CONFIG_H
>  #include "config.h"
>  #endif
> @@ -84,6 +97,22 @@ static void _Futex_Queue_release(
>    _ISR_Local_enable( level );
>  }
>
> +/**
> + * @brief Performs the ``FUTEX_WAIT`` operation.
> + *
> + * @param[in, out] _futex is the futex object.
> + *
> + * @param[in] uaddr is the address to the futex state.
> + *
> + * @param val is the expected futex state value.
> + *
> + * @retval 0 Returns zero if the futex state is equal to the expected
> value.
> + *   In this case the calling thread is enqueued on the thread queue of
> the
> + *   futex object.
> + *
> + * @retval EAGAIN Returns EAGAIN if the futex state is not equal to the
> + *   expected value.
> + */
>  int _Futex_Wait( struct _Futex_Control *_futex, int *uaddr, int val )
>  {
>    Futex_Control        *futex;
> @@ -113,7 +142,7 @@ int _Futex_Wait( struct _Futex_Control *_futex, int
> *uaddr, int val )
>      eno = 0;
>    } else {
>      _Futex_Queue_release( futex, level, &queue_context );
> -    eno = EWOULDBLOCK;
> +    eno = EAGAIN;
>    }
>
>    return eno;
> @@ -143,6 +172,15 @@ static Thread_Control *_Futex_Flush_filter(
>    return the_thread;
>  }
>
> +/**
> + * @brief Performs the ``FUTEX_WAKE`` operation.
> + *
> + * @param[in, out] _futex is the futex.
> + *
> + * @param count is the maximum count of threads to wake up.
> + *
> + * @return Returns the count of woken up threads.
> + */
>  int _Futex_Wake( struct _Futex_Control *_futex, int count )
>  {
>    Futex_Control *futex;
> --
> 2.31.1
>
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> devel at rtems.org
> http://lists.rtems.org/mailman/listinfo/devel
>
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