1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
|
/****************************************************************************
* sched/task_exithook.c
*
* Copyright (C) 2011-2013 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name NuttX nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <stdlib.h>
#include <unistd.h>
#include <signal.h>
#include <debug.h>
#include <errno.h>
#include <nuttx/sched.h>
#include <nuttx/fs/fs.h>
#include "os_internal.h"
#include "group_internal.h"
#include "sig_internal.h"
/****************************************************************************
* Definitions
****************************************************************************/
/****************************************************************************
* Private Type Declarations
****************************************************************************/
/****************************************************************************
* Global Variables
****************************************************************************/
/****************************************************************************
* Private Variables
****************************************************************************/
/****************************************************************************
* Private Function Prototypes
****************************************************************************/
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: task_atexit
*
* Description:
* Call any registerd atexit function(s)
*
****************************************************************************/
#if defined(CONFIG_SCHED_ATEXIT) && !defined(CONFIG_SCHED_ONEXIT)
static inline void task_atexit(FAR struct tcb_s *tcb)
{
FAR struct task_group_s *group = tcb->group;
/* Make sure that we have not already left the group. Only the final
* exitting thread in the task group should trigger the atexit()
* callbacks.
*/
if (group && group->tg_nmembers == 1)
{
#if defined(CONFIG_SCHED_ATEXIT_MAX) && CONFIG_SCHED_ATEXIT_MAX > 1
int index;
/* Call each atexit function in reverse order of registration atexit()
* functions are registered from lower to higher arry indices; they
* must be called in the reverse order of registration when the task
* group exits, i.e., from higher to lower indices.
*/
for (index = CONFIG_SCHED_ATEXIT_MAX-1; index >= 0; index--)
{
if (group->tg_atexitfunc[index])
{
/* Call the atexit function */
(*group->tg_atexitfunc[index])();
/* Nullify the atexit function to prevent its reuse. */
group->tg_atexitfunc[index] = NULL;
}
}
#else
if (group->tg_atexitfunc)
{
/* Call the atexit function */
(*group->tg_atexitfunc)();
/* Nullify the atexit function to prevent its reuse. */
group->tg_atexitfunc = NULL;
}
#endif
}
}
#else
# define task_atexit(tcb)
#endif
/****************************************************************************
* Name: task_onexit
*
* Description:
* Call any registerd on)exit function(s)
*
****************************************************************************/
#ifdef CONFIG_SCHED_ONEXIT
static inline void task_onexit(FAR struct tcb_s *tcb, int status)
{
FAR struct task_group_s *group = tcb->group;
/* Make sure that we have not already left the group. Only the final
* exitting thread in the task group should trigger the atexit()
* callbacks.
*/
if (group && group->tg_nmembers == 1)
{
#if defined(CONFIG_SCHED_ONEXIT_MAX) && CONFIG_SCHED_ONEXIT_MAX > 1
int index;
/* Call each on_exit function in reverse order of registration.
* on_exit() functions are registered from lower to higher arry
* indices; they must be called in the reverse order of registration
* when the task grroup exits, i.e., from higher to lower indices.
*/
for (index = CONFIG_SCHED_ONEXIT_MAX-1; index >= 0; index--)
{
if (group->tg_onexitfunc[index])
{
/* Call the on_exit function */
(*group->tg_onexitfunc[index])(status, group->tg_onexitarg[index]);
/* Nullify the on_exit function to prevent its reuse. */
group->tg_onexitfunc[index] = NULL;
}
}
#else
if (group->tg_onexitfunc)
{
/* Call the on_exit function */
(*group->tg_onexitfunc)(status, group->tg_onexitarg);
/* Nullify the on_exit function to prevent its reuse. */
group->tg_onexitfunc = NULL;
}
#endif
}
}
#else
# define task_onexit(tcb,status)
#endif
/****************************************************************************
* Name: task_exitstatus
*
* Description:
* Report exit status when main task of a task group exits
*
****************************************************************************/
#ifdef CONFIG_SCHED_CHILD_STATUS
static inline void task_exitstatus(FAR struct task_group_s *group, int status)
{
FAR struct child_status_s *child;
/* Check if the parent task group has suppressed retention of
* child exit status information.
*/
if ((group->tg_flags & GROUP_FLAG_NOCLDWAIT) == 0)
{
/* No.. Find the exit status entry for this task in the parent TCB */
child = group_findchild(group, getpid());
DEBUGASSERT(child);
if (child)
{
#ifndef HAVE_GROUP_MEMBERS
/* No group members? Save the exit status */
child->ch_status = status;
#endif
/* Save the exit status.. For the case of HAVE_GROUP_MEMBERS,
* the child status will be as exited until the last member
* of the task group exits.
*/
child->ch_status = status;
}
}
}
#else
# define task_exitstatus(group,status)
#endif /* CONFIG_SCHED_CHILD_STATUS */
/****************************************************************************
* Name: task_groupexit
*
* Description:
* Mark that the final thread of a child task group as exited.
*
****************************************************************************/
#ifdef CONFIG_SCHED_CHILD_STATUS
static inline void task_groupexit(FAR struct task_group_s *group)
{
FAR struct child_status_s *child;
/* Check if the parent task group has suppressed retention of child exit
* status information.
*/
if ((group->tg_flags & GROUP_FLAG_NOCLDWAIT) == 0)
{
/* No.. Find the exit status entry for this task in the parent TCB */
child = group_findchild(group, getpid());
DEBUGASSERT(child);
if (child)
{
/* Mark that all members of the child task group has exit'ed */
child->ch_flags |= CHILD_FLAG_EXITED;
}
}
}
#else
# define task_groupexit(group)
#endif /* CONFIG_SCHED_CHILD_STATUS */
/****************************************************************************
* Name: task_sigchild
*
* Description:
* Send the SIGCHILD signal to the parent thread
*
****************************************************************************/
#ifdef CONFIG_SCHED_HAVE_PARENT
#ifdef HAVE_GROUP_MEMBERS
static inline void task_sigchild(gid_t pgid, FAR struct tcb_s *ctcb, int status)
{
FAR struct task_group_s *chgrp = ctcb->group;
FAR struct task_group_s *pgrp;
siginfo_t info;
DEBUGASSERT(chgrp);
/* Get the parent task group. It is possible that all of the members of
* the parent task group have exited. This would not be an error. In
* this case, the child task group has been orphaned.
*/
pgrp = group_find(chgrp->tg_pgid);
if (!pgrp)
{
/* Set the task group ID to an invalid group ID. The dead parent
* task group ID could get reused some time in the future.
*/
chgrp->tg_pgid = INVALID_GROUP_ID;
return;
}
/* Save the exit status now if this is the main thread of the task group
* that is exiting. Only the exiting main task of a task group carries
* interpretable exit Check if this is the main task that is exiting.
*/
if ((ctcb->flags & TCB_FLAG_TTYPE_MASK) == TCB_FLAG_TTYPE_TASK)
{
task_exitstatus(pgrp, status);
}
/* But only the final exiting thread in a task group, whatever it is,
* should generate SIGCHLD.
*/
if (chgrp->tg_nmembers == 1)
{
/* Mark that all of the threads in the task group have exited */
task_groupexit(pgrp);
/* Create the siginfo structure. We don't actually know the cause.
* That is a bug. Let's just say that the child task just exit-ted
* for now.
*/
info.si_signo = SIGCHLD;
info.si_code = CLD_EXITED;
info.si_value.sival_ptr = NULL;
info.si_pid = ctcb->pid;
info.si_status = status;
/* Send the signal. We need to use this internal interface so that we
* can provide the correct si_code value with the signal.
*/
(void)group_signal(pgrp, &info);
}
}
#else /* HAVE_GROUP_MEMBERS */
static inline void task_sigchild(FAR struct tcb_s *ptcb, FAR struct tcb_s *ctcb, int status)
{
siginfo_t info;
/* If task groups are not supported then we will report SIGCHLD when the
* task exits. Unfortunately, there could still be threads in the group
* that are still running.
*/
if ((ctcb->flags & TCB_FLAG_TTYPE_MASK) == TCB_FLAG_TTYPE_TASK)
{
#ifdef CONFIG_SCHED_CHILD_STATUS
/* Save the exit status now of the main thread */
task_exitstatus(ptcb->group, status);
#else /* CONFIG_SCHED_CHILD_STATUS */
/* Decrement the number of children from this parent */
DEBUGASSERT(ptcb->nchildren > 0);
ptcb->nchildren--;
#endif /* CONFIG_SCHED_CHILD_STATUS */
/* Create the siginfo structure. We don't actually know the cause.
* That is a bug. Let's just say that the child task just exit-ted
* for now.
*/
info.si_signo = SIGCHLD;
info.si_code = CLD_EXITED;
info.si_value.sival_ptr = NULL;
info.si_pid = ctcb->pid;
info.si_status = status;
/* Send the signal. We need to use this internal interface so that we
* can provide the correct si_code value with the signal.
*/
(void)sig_received(ptcb, &info);
}
}
#endif /* HAVE_GROUP_MEMBERS */
#else /* CONFIG_SCHED_HAVE_PARENT */
# define task_sigchild(x,ctcb,status)
#endif /* CONFIG_SCHED_HAVE_PARENT */
/****************************************************************************
* Name: task_leavegroup
*
* Description:
* Send the SIGCHILD signal to the parent thread
*
****************************************************************************/
#ifdef CONFIG_SCHED_HAVE_PARENT
static inline void task_leavegroup(FAR struct tcb_s *ctcb, int status)
{
#ifdef HAVE_GROUP_MEMBERS
DEBUGASSERT(ctcb && ctcb->group);
/* Keep things stationary throughout the following */
sched_lock();
/* Send SIGCHLD to all members of the parent's task group */
task_sigchild(ctcb->group->tg_pgid, ctcb, status);
sched_unlock();
#else
FAR struct tcb_s *ptcb;
/* Keep things stationary throughout the following */
sched_lock();
/* Get the TCB of the receiving, parent task. We do this early to
* handle multiple calls to task_leavegroup. ctcb->ppid is set to an
* invalid value below and the following call will fail if we are
* called again.
*/
ptcb = sched_gettcb(ctcb->ppid);
if (!ptcb)
{
/* The parent no longer exists... bail */
sched_unlock();
return;
}
/* Send SIGCHLD to all members of the parent's task group */
task_sigchild(ptcb, ctcb, status);
/* Forget who our parent was */
ctcb->ppid = INVALID_PROCESS_ID;
sched_unlock();
#endif
}
#else
# define task_leavegroup(ctcb,status)
#endif
/****************************************************************************
* Name: task_exitwakeup
*
* Description:
* Wakeup any tasks waiting for this task to exit
*
****************************************************************************/
#if defined(CONFIG_SCHED_WAITPID) && !defined(CONFIG_SCHED_HAVE_PARENT)
static inline void task_exitwakeup(FAR struct tcb_s *tcb, int status)
{
FAR struct task_group_s *group = tcb->group;
/* Have we already left the group? */
if (group)
{
/* Only tasks return valid status. Record the exit status when the
* task exists. The group, however, may still be executing.
*/
if ((tcb->flags & TCB_FLAG_TTYPE_MASK) == TCB_FLAG_TTYPE_TASK)
{
/* Report the exit status. We do not nullify tg_statloc here
* because we want to prent other tasks from registering for
* the return status. There is only one task per task group,
* there for, this logic should execute exactly once in the
* lifetime of the task group.
*
* "If more than one thread is suspended in waitpid() awaiting
* termination of the same process, exactly one thread will
* return the process status at the time of the target process
* termination."
*
* Hmmm.. what do we return to the others?
*/
if (group->tg_statloc)
{
*group->tg_statloc = status << 8;
}
}
/* Is this the last thread in the group? */
if (group->tg_nmembers == 1)
{
/* Yes.. Wakeup any tasks waiting for this task to exit */
group->tg_statloc = NULL;
while (group->tg_exitsem.semcount < 0)
{
/* Wake up the thread */
sem_post(&group->tg_exitsem);
}
}
}
}
#else
# define task_exitwakeup(tcb, status)
#endif
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: task_hook
*
* Description:
* This function implements some of the internal logic of exit() and
* task_delete(). This function performs some cleanup and other actions
* required when a task exits:
*
* - All open streams are flushed and closed.
* - All functions registered with atexit() and on_exit() are called, in
* the reverse order of their registration.
*
* When called from exit(), the tcb still resides at the head of the ready-
* to-run list. The following logic is safe because we will not be
* returning from the exit() call.
*
* When called from task_delete() we are operating on a different thread;
* on the thread that called task_delete(). In this case, task_delete
* will have already removed the tcb from the ready-to-run list to prevent
* any further action on this task.
*
****************************************************************************/
void task_exithook(FAR struct tcb_s *tcb, int status)
{
/* Under certain conditions, task_exithook() can be called multiple times.
* A bit in the TCB was set the first time this function was called. If
* that bit is set, then just exit doing nothing more..
*/
if ((tcb->flags & TCB_FLAG_EXIT_PROCESSING) != 0)
{
return;
}
/* If exit function(s) were registered, call them now before we do any un-
* initialization. NOTE: In the case of task_delete(), the exit function
* will *not* be called on the thread execution of the task being deleted!
*/
task_atexit(tcb);
/* Call any registered on_exit function(s) */
task_onexit(tcb, status);
/* Leave the task group */
task_leavegroup(tcb, status);
/* Wakeup any tasks waiting for this task to exit */
task_exitwakeup(tcb, status);
/* Flush all streams (File descriptors will be closed when
* the TCB is deallocated).
*/
#if CONFIG_NFILE_STREAMS > 0
(void)lib_flushall(&tcb->group->tg_streamlist);
#endif
/* Leave the task group. Perhaps discarding any un-reaped child
* status (no zombies here!)
*/
#ifdef HAVE_TASK_GROUP
group_leave(tcb);
#endif
/* Deallocate anything left in the TCB's queues */
#ifndef CONFIG_DISABLE_SIGNALS
sig_cleanup(tcb); /* Deallocate Signal lists */
#endif
/* This function can be re-entered in certain cases. Set a flag
* bit in the TCB to not that we have already completed this exit
* processing.
*/
tcb->flags |= TCB_FLAG_EXIT_PROCESSING;
}
|