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[/] [openrisc/] [trunk/] [rtos/] [freertos-6.1.1/] [Demo/] [Common/] [Minimal/] [recmutex.c] - Blame information for rev 609

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1 606 jeremybenn
/*
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    FreeRTOS V6.1.1 - Copyright (C) 2011 Real Time Engineers Ltd.
3
 
4
    ***************************************************************************
5
    *                                                                         *
6
    * If you are:                                                             *
7
    *                                                                         *
8
    *    + New to FreeRTOS,                                                   *
9
    *    + Wanting to learn FreeRTOS or multitasking in general quickly       *
10
    *    + Looking for basic training,                                        *
11
    *    + Wanting to improve your FreeRTOS skills and productivity           *
12
    *                                                                         *
13
    * then take a look at the FreeRTOS books - available as PDF or paperback  *
14
    *                                                                         *
15
    *        "Using the FreeRTOS Real Time Kernel - a Practical Guide"        *
16
    *                  http://www.FreeRTOS.org/Documentation                  *
17
    *                                                                         *
18
    * A pdf reference manual is also available.  Both are usually delivered   *
19
    * to your inbox within 20 minutes to two hours when purchased between 8am *
20
    * and 8pm GMT (although please allow up to 24 hours in case of            *
21
    * exceptional circumstances).  Thank you for your support!                *
22
    *                                                                         *
23
    ***************************************************************************
24
 
25
    This file is part of the FreeRTOS distribution.
26
 
27
    FreeRTOS is free software; you can redistribute it and/or modify it under
28
    the terms of the GNU General Public License (version 2) as published by the
29
    Free Software Foundation AND MODIFIED BY the FreeRTOS exception.
30
    ***NOTE*** The exception to the GPL is included to allow you to distribute
31
    a combined work that includes FreeRTOS without being obliged to provide the
32
    source code for proprietary components outside of the FreeRTOS kernel.
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    FreeRTOS is distributed in the hope that it will be useful, but WITHOUT
34
    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
35
    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
36
    more details. You should have received a copy of the GNU General Public
37
    License and the FreeRTOS license exception along with FreeRTOS; if not it
38
    can be viewed here: http://www.freertos.org/a00114.html and also obtained
39
    by writing to Richard Barry, contact details for whom are available on the
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    FreeRTOS WEB site.
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    1 tab == 4 spaces!
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    http://www.FreeRTOS.org - Documentation, latest information, license and
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    contact details.
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47
    http://www.SafeRTOS.com - A version that is certified for use in safety
48
    critical systems.
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50
    http://www.OpenRTOS.com - Commercial support, development, porting,
51
    licensing and training services.
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*/
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54
/*
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        The tasks defined on this page demonstrate the use of recursive mutexes.
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        For recursive mutex functionality the created mutex should be created using
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        xSemaphoreCreateRecursiveMutex(), then be manipulated
59
        using the xSemaphoreTakeRecursive() and xSemaphoreGiveRecursive() API
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        functions.
61
 
62
        This demo creates three tasks all of which access the same recursive mutex:
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64
        prvRecursiveMutexControllingTask() has the highest priority so executes
65
        first and grabs the mutex.  It then performs some recursive accesses -
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        between each of which it sleeps for a short period to let the lower
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        priority tasks execute.  When it has completed its demo functionality
68
        it gives the mutex back before suspending itself.
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70
        prvRecursiveMutexBlockingTask() attempts to access the mutex by performing
71
        a blocking 'take'.  The blocking task has a lower priority than the
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        controlling     task so by the time it executes the mutex has already been
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        taken by the controlling task,  causing the blocking task to block.  It
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        does not unblock until the controlling task has given the mutex back,
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        and it does not actually run until the controlling task has suspended
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        itself (due to the relative priorities).  When it eventually does obtain
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        the mutex all it does is give the mutex back prior to also suspending
78
        itself.  At this point both the controlling task and the blocking task are
79
        suspended.
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81
        prvRecursiveMutexPollingTask() runs at the idle priority.  It spins round
82
        a tight loop attempting to obtain the mutex with a non-blocking call.  As
83
        the lowest priority task it will not successfully obtain the mutex until
84
        both the controlling and blocking tasks are suspended.  Once it eventually
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        does obtain the mutex it first unsuspends both the controlling task and
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        blocking task prior to giving the mutex back - resulting in the polling
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        task temporarily inheriting the controlling tasks priority.
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*/
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90
/* Scheduler include files. */
91
#include "FreeRTOS.h"
92
#include "task.h"
93
#include "semphr.h"
94
 
95
/* Demo app include files. */
96
#include "recmutex.h"
97
 
98
/* Priorities assigned to the three tasks. */
99
#define recmuCONTROLLING_TASK_PRIORITY  ( tskIDLE_PRIORITY + 2 )
100
#define recmuBLOCKING_TASK_PRIORITY             ( tskIDLE_PRIORITY + 1 )
101
#define recmuPOLLING_TASK_PRIORITY              ( tskIDLE_PRIORITY + 0 )
102
 
103
/* The recursive call depth. */
104
#define recmuMAX_COUNT                                  ( 10 )
105
 
106
/* Misc. */
107
#define recmuSHORT_DELAY                                ( 20 / portTICK_RATE_MS )
108
#define recmuNO_DELAY                                   ( ( portTickType ) 0 )
109
#define recmuTWO_TICK_DELAY                             ( ( portTickType ) 2 )
110
 
111
/* The three tasks as described at the top of this file. */
112
static void prvRecursiveMutexControllingTask( void *pvParameters );
113
static void prvRecursiveMutexBlockingTask( void *pvParameters );
114
static void prvRecursiveMutexPollingTask( void *pvParameters );
115
 
116
/* The mutex used by the demo. */
117
static xSemaphoreHandle xMutex;
118
 
119
/* Variables used to detect and latch errors. */
120
static volatile portBASE_TYPE xErrorOccurred = pdFALSE, xControllingIsSuspended = pdFALSE, xBlockingIsSuspended = pdFALSE;
121
static volatile unsigned portBASE_TYPE uxControllingCycles = 0, uxBlockingCycles = 0, uxPollingCycles = 0;
122
 
123
/* Handles of the two higher priority tasks, required so they can be resumed
124
(unsuspended). */
125
static xTaskHandle xControllingTaskHandle, xBlockingTaskHandle;
126
 
127
/*-----------------------------------------------------------*/
128
 
129
void vStartRecursiveMutexTasks( void )
130
{
131
        /* Just creates the mutex and the three tasks. */
132
 
133
        xMutex = xSemaphoreCreateRecursiveMutex();
134
 
135
        /* vQueueAddToRegistry() adds the mutex to the registry, if one is
136
        in use.  The registry is provided as a means for kernel aware
137
        debuggers to locate mutex and has no purpose if a kernel aware debugger
138
        is not being used.  The call to vQueueAddToRegistry() will be removed
139
        by the pre-processor if configQUEUE_REGISTRY_SIZE is not defined or is
140
        defined to be less than 1. */
141
        vQueueAddToRegistry( ( xQueueHandle ) xMutex, ( signed portCHAR * ) "Recursive_Mutex" );
142
 
143
 
144
        if( xMutex != NULL )
145
        {
146
                xTaskCreate( prvRecursiveMutexControllingTask, ( signed portCHAR * ) "Rec1", configMINIMAL_STACK_SIZE, NULL, recmuCONTROLLING_TASK_PRIORITY, &xControllingTaskHandle );
147
        xTaskCreate( prvRecursiveMutexBlockingTask, ( signed portCHAR * ) "Rec2", configMINIMAL_STACK_SIZE, NULL, recmuBLOCKING_TASK_PRIORITY, &xBlockingTaskHandle );
148
        xTaskCreate( prvRecursiveMutexPollingTask, ( signed portCHAR * ) "Rec3", configMINIMAL_STACK_SIZE, NULL, recmuPOLLING_TASK_PRIORITY, NULL );
149
        }
150
}
151
/*-----------------------------------------------------------*/
152
 
153
static void prvRecursiveMutexControllingTask( void *pvParameters )
154
{
155
unsigned portBASE_TYPE ux;
156
 
157
        /* Just to remove compiler warning. */
158
        ( void ) pvParameters;
159
 
160
        for( ;; )
161
        {
162
                /* Should not be able to 'give' the mutex, as we have not yet 'taken'
163
                it.   The first time through, the mutex will not have been used yet,
164
                subsequent times through, at this point the mutex will be held by the
165
                polling task. */
166
                if( xSemaphoreGiveRecursive( xMutex ) == pdPASS )
167
                {
168
                        xErrorOccurred = pdTRUE;
169
                }
170
 
171
                for( ux = 0; ux < recmuMAX_COUNT; ux++ )
172
                {
173
                        /* We should now be able to take the mutex as many times as
174
                        we like.
175
 
176
                        The first time through the mutex will be immediately available, on
177
                        subsequent times through the mutex will be held by the polling task
178
                        at this point and this Take will cause the polling task to inherit
179
                        the priority of this task.  In this case the block time must be
180
                        long enough to ensure the polling task will execute again before the
181
                        block time expires.  If the block time does expire then the error
182
                        flag will be set here. */
183
                        if( xSemaphoreTakeRecursive( xMutex, recmuTWO_TICK_DELAY ) != pdPASS )
184
                        {
185
                                xErrorOccurred = pdTRUE;
186
                        }
187
 
188
                        /* Ensure the other task attempting to access the mutex (and the
189
                        other demo tasks) are able to execute to ensure they either block
190
                        (where a block time is specified) or return an error (where no
191
                        block time is specified) as the mutex is held by this task. */
192
                        vTaskDelay( recmuSHORT_DELAY );
193
                }
194
 
195
                /* For each time we took the mutex, give it back. */
196
                for( ux = 0; ux < recmuMAX_COUNT; ux++ )
197
                {
198
                        /* Ensure the other task attempting to access the mutex (and the
199
                        other demo tasks) are able to execute. */
200
                        vTaskDelay( recmuSHORT_DELAY );
201
 
202
                        /* We should now be able to give the mutex as many times as we
203
                        took it.  When the mutex is available again the Blocking task
204
                        should be unblocked but not run because it has a lower priority
205
                        than this task.  The polling task should also not run at this point
206
                        as it too has a lower priority than this task. */
207
                        if( xSemaphoreGiveRecursive( xMutex ) != pdPASS )
208
                        {
209
                                xErrorOccurred = pdTRUE;
210
                        }
211
                }
212
 
213
                /* Having given it back the same number of times as it was taken, we
214
                should no longer be the mutex owner, so the next give sh ould fail. */
215
                if( xSemaphoreGiveRecursive( xMutex ) == pdPASS )
216
                {
217
                        xErrorOccurred = pdTRUE;
218
                }
219
 
220
                /* Keep count of the number of cycles this task has performed so a
221
                stall can be detected. */
222
                uxControllingCycles++;
223
 
224
                /* Suspend ourselves to the blocking task can execute. */
225
                xControllingIsSuspended = pdTRUE;
226
                vTaskSuspend( NULL );
227
                xControllingIsSuspended = pdFALSE;
228
        }
229
}
230
/*-----------------------------------------------------------*/
231
 
232
static void prvRecursiveMutexBlockingTask( void *pvParameters )
233
{
234
        /* Just to remove compiler warning. */
235
        ( void ) pvParameters;
236
 
237
        for( ;; )
238
        {
239
                /* This task will run while the controlling task is blocked, and the
240
                controlling task will block only once it has the mutex - therefore
241
                this call should block until the controlling task has given up the
242
                mutex, and not actually execute past this call until the controlling
243
                task is suspended. */
244
                if( xSemaphoreTakeRecursive( xMutex, portMAX_DELAY ) == pdPASS )
245
                {
246
                        if( xControllingIsSuspended != pdTRUE )
247
                        {
248
                                /* Did not expect to execute until the controlling task was
249
                                suspended. */
250
                                xErrorOccurred = pdTRUE;
251
                        }
252
                        else
253
                        {
254
                                /* Give the mutex back before suspending ourselves to allow
255
                                the polling task to obtain the mutex. */
256
                                if( xSemaphoreGiveRecursive( xMutex ) != pdPASS )
257
                                {
258
                                        xErrorOccurred = pdTRUE;
259
                                }
260
 
261
                                xBlockingIsSuspended = pdTRUE;
262
                                vTaskSuspend( NULL );
263
                                xBlockingIsSuspended = pdFALSE;
264
                        }
265
                }
266
                else
267
                {
268
                        /* We should not leave the xSemaphoreTakeRecursive() function
269
                        until the mutex was obtained. */
270
                        xErrorOccurred = pdTRUE;
271
                }
272
 
273
                /* The controlling and blocking tasks should be in lock step. */
274
                if( uxControllingCycles != ( uxBlockingCycles + 1 ) )
275
                {
276
                        xErrorOccurred = pdTRUE;
277
                }
278
 
279
                /* Keep count of the number of cycles this task has performed so a
280
                stall can be detected. */
281
                uxBlockingCycles++;
282
        }
283
}
284
/*-----------------------------------------------------------*/
285
 
286
static void prvRecursiveMutexPollingTask( void *pvParameters )
287
{
288
        /* Just to remove compiler warning. */
289
        ( void ) pvParameters;
290
 
291
        for( ;; )
292
        {
293
                /* Keep attempting to obtain the mutex.  We should only obtain it when
294
                the blocking task has suspended itself, which in turn should only
295
                happen when the controlling task is also suspended. */
296
                if( xSemaphoreTakeRecursive( xMutex, recmuNO_DELAY ) == pdPASS )
297
                {
298
                        /* Is the blocking task suspended? */
299
                        if( ( xBlockingIsSuspended != pdTRUE ) || ( xControllingIsSuspended != pdTRUE ) )
300
                        {
301
                                xErrorOccurred = pdTRUE;
302
                        }
303
                        else
304
                        {
305
                                /* Keep count of the number of cycles this task has performed
306
                                so a stall can be detected. */
307
                                uxPollingCycles++;
308
 
309
                                /* We can resume the other tasks here even though they have a
310
                                higher priority than the polling task.  When they execute they
311
                                will attempt to obtain the mutex but fail because the polling
312
                                task is still the mutex holder.  The polling task (this task)
313
                                will then inherit the higher priority.  The Blocking task will
314
                                block indefinitely when it attempts to obtain the mutex, the
315
                                Controlling task will only block for a fixed period and an
316
                                error will be latched if the polling task has not returned the
317
                                mutex by the time this fixed period has expired. */
318
                                vTaskResume( xBlockingTaskHandle );
319
                vTaskResume( xControllingTaskHandle );
320
 
321
                                /* The other two tasks should now have executed and no longer
322
                                be suspended. */
323
                                if( ( xBlockingIsSuspended == pdTRUE ) || ( xControllingIsSuspended == pdTRUE ) )
324
                                {
325
                                        xErrorOccurred = pdTRUE;
326
                                }
327
 
328
                                /* Release the mutex, disinheriting the higher priority again. */
329
                                if( xSemaphoreGiveRecursive( xMutex ) != pdPASS )
330
                                {
331
                                        xErrorOccurred = pdTRUE;
332
                                }
333
                        }
334
                }
335
 
336
                #if configUSE_PREEMPTION == 0
337
                {
338
                        taskYIELD();
339
                }
340
                #endif
341
        }
342
}
343
/*-----------------------------------------------------------*/
344
 
345
/* This is called to check that all the created tasks are still running. */
346
portBASE_TYPE xAreRecursiveMutexTasksStillRunning( void )
347
{
348
portBASE_TYPE xReturn;
349
static unsigned portBASE_TYPE uxLastControllingCycles = 0, uxLastBlockingCycles = 0, uxLastPollingCycles = 0;
350
 
351
        /* Is the controlling task still cycling? */
352
        if( uxLastControllingCycles == uxControllingCycles )
353
        {
354
                xErrorOccurred = pdTRUE;
355
        }
356
        else
357
        {
358
                uxLastControllingCycles = uxControllingCycles;
359
        }
360
 
361
        /* Is the blocking task still cycling? */
362
        if( uxLastBlockingCycles == uxBlockingCycles )
363
        {
364
                xErrorOccurred = pdTRUE;
365
        }
366
        else
367
        {
368
                uxLastBlockingCycles = uxBlockingCycles;
369
        }
370
 
371
        /* Is the polling task still cycling? */
372
        if( uxLastPollingCycles == uxPollingCycles )
373
        {
374
                xErrorOccurred = pdTRUE;
375
        }
376
        else
377
        {
378
                uxLastPollingCycles = uxPollingCycles;
379
        }
380
 
381
        if( xErrorOccurred == pdTRUE )
382
        {
383
                xReturn = pdFAIL;
384
        }
385
        else
386
        {
387
                xReturn = pdTRUE;
388
        }
389
 
390
        return xReturn;
391
}
392
 
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