rtems/src/regionprocessqueue.c

0001 /* SPDX-License-Identifier: BSD-2-Clause */
0002
0003 /**
0004  * @file
0005  *
0006  * @ingroup RTEMSImplClassicRegion
0007  *
0008  * @brief This source file contains the implementation of
0009  *   _Region_Process_queue().
0010  */
0011
0012 /*
0013  *  COPYRIGHT (c) 1989-1999.
0014  *  On-Line Applications Research Corporation (OAR).
0015  *
0016  * Redistribution and use in source and binary forms, with or without
0017  * modification, are permitted provided that the following conditions
0018  * are met:
0019  * 1. Redistributions of source code must retain the above copyright
0020  *    notice, this list of conditions and the following disclaimer.
0021  * 2. Redistributions in binary form must reproduce the above copyright
0022  *    notice, this list of conditions and the following disclaimer in the
0023  *    documentation and/or other materials provided with the distribution.
0024  *
0025  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
0026  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
0027  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
0028  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
0029  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
0030  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
0031  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
0032  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
0033  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
0034  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
0035  * POSSIBILITY OF SUCH DAMAGE.
0036  */
0037
0038 #ifdef HAVE_CONFIG_H
0039 #include "config.h"
0040 #endif
0041
0042 #include <rtems/rtems/regionimpl.h>
0043 #include <rtems/score/status.h>
0044 #include <rtems/score/threadqimpl.h>
0045
0046 void _Region_Process_queue(
0047   Region_Control *the_region
0048 )
0049 {
0050   Per_CPU_Control *cpu_self;
0051   Thread_Control  *the_thread;
0052   void            *the_segment;
0053
0054   /*
0055    *  Switch from using the memory allocation mutex to using a
0056    *  dispatching disabled critical section.  We have to do this
0057    *  because this thread may unblock one or more threads that were
0058    *  waiting on memory.
0059    *
0060    *  NOTE: Be sure to disable dispatching before unlocking the mutex
0061    *        since we do not want to open a window where a context
0062    *        switch could occur.
0063    */
0064   cpu_self = _Thread_Dispatch_disable();
0065   _Region_Unlock( the_region );
0066
0067   /*
0068    *  NOTE: The following loop is O(n) where n is the number of
0069    *        threads whose memory request is satisfied.
0070    */
0071   for ( ; ; ) {
0072     the_thread = _Thread_queue_First(
0073       &the_region->Wait_queue,
0074       the_region->wait_operations
0075     );
0076
0077     if ( the_thread == NULL )
0078       break;
0079
0080     the_segment = (void **) _Region_Allocate_segment(
0081       the_region,
0082       the_thread->Wait.count
0083     );
0084
0085     if ( the_segment == NULL )
0086       break;
0087
0088     *(void **)the_thread->Wait.return_argument = the_segment;
0089     _Thread_queue_Extract( the_thread );
0090     the_thread->Wait.return_code = STATUS_SUCCESSFUL;
0091   }
0092
0093   _Thread_Dispatch_enable( cpu_self );
0094 }