posix/src/mutexsetprioceiling.c

0001 /* SPDX-License-Identifier: BSD-2-Clause */
0002
0003 /**
0004  * @file
0005  *
0006  * @ingroup POSIXAPI
0007  *
0008  * @brief Changes the Priority Ceiling of a Mutex and Releases it
0009  */
0010
0011 /*
0012  *  COPYRIGHT (c) 1989-2009.
0013  *  On-Line Applications Research Corporation (OAR).
0014  *
0015  * Redistribution and use in source and binary forms, with or without
0016  * modification, are permitted provided that the following conditions
0017  * are met:
0018  * 1. Redistributions of source code must retain the above copyright
0019  *    notice, this list of conditions and the following disclaimer.
0020  * 2. Redistributions in binary form must reproduce the above copyright
0021  *    notice, this list of conditions and the following disclaimer in the
0022  *    documentation and/or other materials provided with the distribution.
0023  *
0024  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
0025  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
0026  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
0027  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
0028  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
0029  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
0030  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
0031  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
0032  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
0033  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
0034  * POSSIBILITY OF SUCH DAMAGE.
0035  */
0036
0037 #ifdef HAVE_CONFIG_H
0038 #include "config.h"
0039 #endif
0040
0041 #include <rtems/posix/muteximpl.h>
0042 #include <rtems/posix/priorityimpl.h>
0043
0044 /*
0045  *  13.6.2 Change the Priority Ceiling of a Mutex, P1003.1c/Draft 10, p. 131
0046  */
0047
0048 int pthread_mutex_setprioceiling(
0049   pthread_mutex_t   *mutex,
0050   int                prioceiling,
0051   int               *old_ceiling
0052 )
0053 {
0054   POSIX_Mutex_Control *the_mutex;
0055   int                  error;
0056   int                  unlock_error;
0057
0058   if ( old_ceiling == NULL ) {
0059     return EINVAL;
0060   }
0061
0062   /*
0063    *  Must acquire the mutex before we can change it's ceiling.
0064    *  POSIX says block until we acquire it.
0065    */
0066   error = pthread_mutex_lock( mutex );
0067   if ( error != 0 ) {
0068     _Assert( error == EINVAL );
0069     return EINVAL;
0070   }
0071
0072   the_mutex = _POSIX_Mutex_Get( mutex );
0073
0074   if (
0075     _POSIX_Mutex_Get_protocol( the_mutex->flags )
0076       == POSIX_MUTEX_PRIORITY_CEILING
0077   ) {
0078     const Scheduler_Control *scheduler;
0079     bool                     valid;
0080     Priority_Control         new_priority;
0081     Priority_Control         old_priority;
0082
0083     scheduler = _POSIX_Mutex_Get_scheduler( the_mutex );
0084     old_priority = _POSIX_Mutex_Get_priority( the_mutex );
0085     *old_ceiling = _POSIX_Priority_From_core( scheduler, old_priority );
0086
0087     new_priority = _POSIX_Priority_To_core( scheduler, prioceiling, &valid );
0088     if ( valid ) {
0089       Thread_queue_Context  queue_context;
0090       Per_CPU_Control      *cpu_self;
0091
0092       _Thread_queue_Context_initialize( &queue_context );
0093       _Thread_queue_Context_clear_priority_updates( &queue_context );
0094       _POSIX_Mutex_Set_priority(
0095         the_mutex,
0096         new_priority,
0097         &queue_context
0098       );
0099       cpu_self = _Thread_Dispatch_disable();
0100       _Thread_Priority_update( &queue_context );
0101       _Thread_Dispatch_enable( cpu_self );
0102       error = 0;
0103     } else {
0104       error = EINVAL;
0105     }
0106   } else {
0107     *old_ceiling = 0;
0108     error = 0;
0109   }
0110
0111   unlock_error = pthread_mutex_unlock( mutex );
0112   _Assert( unlock_error == 0 );
0113   (void) unlock_error;
0114   return error;
0115 }