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[glibc.git] / linuxthreads / manager.c
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1 /* Linuxthreads - a simple clone()-based implementation of Posix */
2 /* threads for Linux. */
3 /* Copyright (C) 1996 Xavier Leroy (Xavier.Leroy@inria.fr) */
4 /* */
5 /* This program is free software; you can redistribute it and/or */
6 /* modify it under the terms of the GNU Library General Public License */
7 /* as published by the Free Software Foundation; either version 2 */
8 /* of the License, or (at your option) any later version. */
9 /* */
10 /* This program is distributed in the hope that it will be useful, */
11 /* but WITHOUT ANY WARRANTY; without even the implied warranty of */
12 /* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the */
13 /* GNU Library General Public License for more details. */
15 /* The "thread manager" thread: manages creation and termination of threads */
17 #include <errno.h>
18 #include <sched.h>
19 #include <stddef.h>
20 #include <stdio.h>
21 #include <stdlib.h>
22 #include <string.h>
23 #include <unistd.h>
24 #include <sys/poll.h> /* for poll */
25 #include <sys/mman.h> /* for mmap */
26 #include <sys/param.h>
27 #include <sys/time.h>
28 #include <sys/wait.h> /* for waitpid macros */
29 #include <linux/tasks.h>
31 #include "pthread.h"
32 #include "internals.h"
33 #include "spinlock.h"
34 #include "restart.h"
35 #include "semaphore.h"
37 /* Array of active threads. Entry 0 is reserved for the initial thread. */
38 struct pthread_handle_struct __pthread_handles[PTHREAD_THREADS_MAX] =
39 { { LOCK_INITIALIZER, &__pthread_initial_thread, 0},
40 { LOCK_INITIALIZER, &__pthread_manager_thread, 0}, /* All NULLs */ };
42 /* Indicate whether at least one thread has a user-defined stack (if 1),
43 or if all threads have stacks supplied by LinuxThreads (if 0). */
44 int __pthread_nonstandard_stacks = 0;
46 /* Number of active entries in __pthread_handles (used by gdb) */
47 volatile int __pthread_handles_num = 2;
49 /* Whether to use debugger additional actions for thread creation
50 (set to 1 by gdb) */
51 volatile int __pthread_threads_debug = 0;
53 /* Mapping from stack segment to thread descriptor. */
54 /* Stack segment numbers are also indices into the __pthread_handles array. */
55 /* Stack segment number 0 is reserved for the initial thread. */
57 static inline pthread_descr thread_segment(int seg)
59 return (pthread_descr)(THREAD_STACK_START_ADDRESS - (seg - 1) * STACK_SIZE)
60 - 1;
63 /* Flag set in signal handler to record child termination */
65 static volatile int terminated_children = 0;
67 /* Flag set when the initial thread is blocked on pthread_exit waiting
68 for all other threads to terminate */
70 static int main_thread_exiting = 0;
72 /* Counter used to generate unique thread identifier.
73 Thread identifier is pthread_threads_counter + segment. */
75 static pthread_t pthread_threads_counter = 0;
77 /* Forward declarations */
79 static int pthread_handle_create(pthread_t *thread, const pthread_attr_t *attr,
80 void * (*start_routine)(void *), void *arg,
81 sigset_t *mask, int father_pid);
82 static void pthread_handle_free(pthread_t th_id);
83 static void pthread_handle_exit(pthread_descr issuing_thread, int exitcode);
84 static void pthread_reap_children(void);
85 static void pthread_kill_all_threads(int sig, int main_thread_also);
87 /* The server thread managing requests for thread creation and termination */
89 int __pthread_manager(void *arg)
91 int reqfd = (int)arg;
92 struct pollfd ufd;
93 sigset_t mask;
94 int n;
95 struct pthread_request request;
97 /* If we have special thread_self processing, initialize it. */
98 #ifdef INIT_THREAD_SELF
99 INIT_THREAD_SELF(&__pthread_manager_thread, 1);
100 #endif
101 /* Set the error variable. */
102 __pthread_manager_thread.p_errnop = &__pthread_manager_thread.p_errno;
103 __pthread_manager_thread.p_h_errnop = &__pthread_manager_thread.p_h_errno;
104 /* Block all signals except __pthread_sig_restart, __pthread_sig_cancel
105 and SIGTRAP */
106 sigfillset(&mask);
107 sigdelset(&mask, __pthread_sig_restart);
108 sigdelset(&mask, __pthread_sig_cancel); /* for debugging new threads */
109 sigdelset(&mask, SIGTRAP); /* for debugging purposes */
110 sigprocmask(SIG_SETMASK, &mask, NULL);
111 /* Raise our priority to match that of main thread */
112 __pthread_manager_adjust_prio(__pthread_main_thread->p_priority);
113 /* Synchronize debugging of the thread manager */
114 n = __libc_read(reqfd, (char *)&request, sizeof(request));
115 ASSERT(n == sizeof(request) && request.req_kind == REQ_DEBUG);
116 ufd.fd = reqfd;
117 ufd.events = POLLIN;
118 /* Enter server loop */
119 while(1) {
120 n = __poll(&ufd, 1, 2000);
122 /* Check for termination of the main thread */
123 if (getppid() == 1) {
124 pthread_kill_all_threads(SIGKILL, 0);
125 _exit(0);
127 /* Check for dead children */
128 if (terminated_children) {
129 terminated_children = 0;
130 pthread_reap_children();
132 /* Read and execute request */
133 if (n == 1 && (ufd.revents & POLLIN)) {
134 n = __libc_read(reqfd, (char *)&request, sizeof(request));
135 ASSERT(n == sizeof(request));
136 switch(request.req_kind) {
137 case REQ_CREATE:
138 request.req_thread->p_retcode =
139 pthread_handle_create((pthread_t *) &request.req_thread->p_retval,
140 request.req_args.create.attr,
141 request.req_args.create.fn,
142 request.req_args.create.arg,
143 &request.req_args.create.mask,
144 request.req_thread->p_pid);
145 restart(request.req_thread);
146 break;
147 case REQ_FREE:
148 pthread_handle_free(request.req_args.free.thread_id);
149 break;
150 case REQ_PROCESS_EXIT:
151 pthread_handle_exit(request.req_thread,
152 request.req_args.exit.code);
153 break;
154 case REQ_MAIN_THREAD_EXIT:
155 main_thread_exiting = 1;
156 if (__pthread_main_thread->p_nextlive == __pthread_main_thread) {
157 restart(__pthread_main_thread);
158 return 0;
160 break;
161 case REQ_POST:
162 sem_post(request.req_args.post);
163 break;
164 case REQ_DEBUG:
165 /* Make gdb aware of new thread */
166 if (__pthread_threads_debug) raise(__pthread_sig_cancel);
167 restart(request.req_thread);
168 break;
174 /* Process creation */
176 static int pthread_start_thread(void *arg)
178 pthread_descr self = (pthread_descr) arg;
179 struct pthread_request request;
180 void * outcome;
181 /* Initialize special thread_self processing, if any. */
182 #ifdef INIT_THREAD_SELF
183 INIT_THREAD_SELF(self, self->p_nr);
184 #endif
185 /* Make sure our pid field is initialized, just in case we get there
186 before our father has initialized it. */
187 THREAD_SETMEM(self, p_pid, __getpid());
188 /* Initial signal mask is that of the creating thread. (Otherwise,
189 we'd just inherit the mask of the thread manager.) */
190 sigprocmask(SIG_SETMASK, &self->p_start_args.mask, NULL);
191 /* Set the scheduling policy and priority for the new thread, if needed */
192 if (THREAD_GETMEM(self, p_start_args.schedpolicy) >= 0)
193 __sched_setscheduler(THREAD_GETMEM(self, p_pid),
194 THREAD_GETMEM(self, p_start_args.schedpolicy),
195 &self->p_start_args.schedparam);
196 /* Make gdb aware of new thread */
197 if (__pthread_threads_debug) {
198 request.req_thread = self;
199 request.req_kind = REQ_DEBUG;
200 __libc_write(__pthread_manager_request,
201 (char *) &request, sizeof(request));
202 suspend(self);
204 /* Run the thread code */
205 outcome = self->p_start_args.start_routine(THREAD_GETMEM(self,
206 p_start_args.arg));
207 /* Exit with the given return value */
208 pthread_exit(outcome);
209 return 0;
212 static int pthread_allocate_stack(const pthread_attr_t *attr,
213 pthread_descr default_new_thread,
214 int pagesize,
215 pthread_descr * out_new_thread,
216 char ** out_new_thread_bottom,
217 char ** out_guardaddr,
218 size_t * out_guardsize)
220 pthread_descr new_thread;
221 char * new_thread_bottom;
222 char * guardaddr;
223 size_t stacksize, guardsize;
225 if (attr != NULL && attr->stackaddr_set)
227 /* The user provided a stack. */
228 new_thread =
229 (pthread_descr) ((long)(attr->stackaddr) & -sizeof(void *)) - 1;
230 new_thread_bottom = (char *) attr->stackaddr - attr->stacksize;
231 guardaddr = NULL;
232 guardsize = 0;
234 else
236 /* Allocate space for stack and thread descriptor at default address */
237 new_thread = default_new_thread;
238 new_thread_bottom = (char *) new_thread - STACK_SIZE;
239 if (mmap((caddr_t)((char *)(new_thread + 1) - INITIAL_STACK_SIZE),
240 INITIAL_STACK_SIZE, PROT_READ | PROT_WRITE | PROT_EXEC,
241 MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED | MAP_GROWSDOWN,
242 -1, 0) == MAP_FAILED)
243 /* Bad luck, this segment is already mapped. */
244 return -1;
245 /* We manage to get a stack. Now see whether we need a guard
246 and allocate it if necessary. Notice that the default
247 attributes (stack_size = STACK_SIZE - pagesize and
248 guardsize = pagesize) do not need a guard page, since
249 the RLIMIT_STACK soft limit prevents stacks from
250 running into one another. */
251 if (attr == NULL ||
252 attr->guardsize == 0 ||
253 (attr->guardsize == pagesize &&
254 attr->stacksize == STACK_SIZE - pagesize))
256 /* We don't need a guard page. */
257 guardaddr = NULL;
258 guardsize = 0;
260 else
262 /* Put a bad page at the bottom of the stack */
263 stacksize = roundup(attr->stacksize, pagesize);
264 if (stacksize >= STACK_SIZE - pagesize)
265 stacksize = STACK_SIZE - pagesize;
266 guardaddr = (void *)new_thread - stacksize;
267 guardsize = attr->guardsize;
268 if (mmap ((caddr_t) guardaddr, guardsize, 0, MAP_FIXED, -1, 0)
269 == MAP_FAILED)
271 /* We don't make this an error. */
272 guardaddr = NULL;
273 guardsize = 0;
277 *out_new_thread = new_thread;
278 *out_new_thread_bottom = new_thread_bottom;
279 *out_guardaddr = guardaddr;
280 *out_guardsize = guardsize;
281 return 0;
284 static int pthread_handle_create(pthread_t *thread, const pthread_attr_t *attr,
285 void * (*start_routine)(void *), void *arg,
286 sigset_t * mask, int father_pid)
288 size_t sseg;
289 int pid;
290 pthread_descr new_thread;
291 char * new_thread_bottom;
292 pthread_t new_thread_id;
293 char *guardaddr = NULL;
294 size_t guardsize = 0;
295 int pagesize = __getpagesize();
297 /* First check whether we have to change the policy and if yes, whether
298 we can do this. Normally this should be done by examining the
299 return value of the __sched_setscheduler call in pthread_start_thread
300 but this is hard to implement. FIXME */
301 if (attr != NULL && attr->schedpolicy != SCHED_OTHER && geteuid () != 0)
302 return EPERM;
303 /* Find a free segment for the thread, and allocate a stack if needed */
304 for (sseg = 2; ; sseg++)
306 if (sseg >= PTHREAD_THREADS_MAX)
307 return EAGAIN;
308 if (__pthread_handles[sseg].h_descr != NULL)
309 continue;
310 if (pthread_allocate_stack(attr, thread_segment(sseg), pagesize,
311 &new_thread, &new_thread_bottom,
312 &guardaddr, &guardsize) == 0)
313 break;
315 /* Allocate new thread identifier */
316 pthread_threads_counter += PTHREAD_THREADS_MAX;
317 new_thread_id = sseg + pthread_threads_counter;
318 /* Initialize the thread descriptor */
319 new_thread->p_nextwaiting = NULL;
320 new_thread->p_tid = new_thread_id;
321 new_thread->p_priority = 0;
322 new_thread->p_lock = &(__pthread_handles[sseg].h_lock);
323 new_thread->p_signal = 0;
324 new_thread->p_signal_jmp = NULL;
325 new_thread->p_cancel_jmp = NULL;
326 new_thread->p_terminated = 0;
327 new_thread->p_detached = attr == NULL ? 0 : attr->detachstate;
328 new_thread->p_exited = 0;
329 new_thread->p_retval = NULL;
330 new_thread->p_joining = NULL;
331 new_thread->p_cleanup = NULL;
332 new_thread->p_cancelstate = PTHREAD_CANCEL_ENABLE;
333 new_thread->p_canceltype = PTHREAD_CANCEL_DEFERRED;
334 new_thread->p_canceled = 0;
335 new_thread->p_errnop = &new_thread->p_errno;
336 new_thread->p_errno = 0;
337 new_thread->p_h_errnop = &new_thread->p_h_errno;
338 new_thread->p_h_errno = 0;
339 new_thread->p_in_sighandler = NULL;
340 new_thread->p_sigwaiting = 0;
341 new_thread->p_guardaddr = guardaddr;
342 new_thread->p_guardsize = guardsize;
343 new_thread->p_userstack = attr != NULL && attr->stackaddr_set;
344 memset (new_thread->p_specific, '\0',
345 PTHREAD_KEY_1STLEVEL_SIZE * sizeof (new_thread->p_specific[0]));
346 new_thread->p_self = new_thread;
347 new_thread->p_nr = sseg;
348 /* Initialize the thread handle */
349 __pthread_init_lock(&__pthread_handles[sseg].h_lock);
350 __pthread_handles[sseg].h_descr = new_thread;
351 __pthread_handles[sseg].h_bottom = new_thread_bottom;
352 /* Determine scheduling parameters for the thread */
353 new_thread->p_start_args.schedpolicy = -1;
354 if (attr != NULL) {
355 switch(attr->inheritsched) {
356 case PTHREAD_EXPLICIT_SCHED:
357 new_thread->p_start_args.schedpolicy = attr->schedpolicy;
358 memcpy (&new_thread->p_start_args.schedparam, &attr->schedparam,
359 sizeof (struct sched_param));
360 break;
361 case PTHREAD_INHERIT_SCHED:
362 /* schedpolicy doesn't need to be set, only get priority */
363 __sched_getparam(father_pid, &new_thread->p_start_args.schedparam);
364 break;
366 new_thread->p_priority =
367 new_thread->p_start_args.schedparam.sched_priority;
369 /* Finish setting up arguments to pthread_start_thread */
370 new_thread->p_start_args.start_routine = start_routine;
371 new_thread->p_start_args.arg = arg;
372 new_thread->p_start_args.mask = *mask;
373 /* Raise priority of thread manager if needed */
374 __pthread_manager_adjust_prio(new_thread->p_priority);
375 /* Do the cloning */
376 pid = __clone(pthread_start_thread, (void **) new_thread,
377 CLONE_VM | CLONE_FS | CLONE_FILES | CLONE_SIGHAND |
378 #ifdef CLONE_PTRACE
379 CLONE_PTRACE |
380 #endif
381 __pthread_sig_restart, new_thread);
382 /* Check if cloning succeeded */
383 if (pid == -1) {
384 /* Free the stack if we allocated it */
385 if (attr == NULL || !attr->stackaddr_set)
387 munmap((caddr_t)((char *)(new_thread+1) - INITIAL_STACK_SIZE),
388 INITIAL_STACK_SIZE);
389 if (new_thread->p_guardsize != 0)
390 munmap(new_thread->p_guardaddr, new_thread->p_guardsize);
392 __pthread_handles[sseg].h_descr = NULL;
393 __pthread_handles[sseg].h_bottom = NULL;
394 __pthread_handles_num--;
395 return errno;
397 /* Insert new thread in doubly linked list of active threads */
398 new_thread->p_prevlive = __pthread_main_thread;
399 new_thread->p_nextlive = __pthread_main_thread->p_nextlive;
400 __pthread_main_thread->p_nextlive->p_prevlive = new_thread;
401 __pthread_main_thread->p_nextlive = new_thread;
402 /* Set pid field of the new thread, in case we get there before the
403 child starts. */
404 new_thread->p_pid = pid;
405 /* We're all set */
406 *thread = new_thread_id;
407 return 0;
411 /* Try to free the resources of a thread when requested by pthread_join
412 or pthread_detach on a terminated thread. */
414 static void pthread_free(pthread_descr th)
416 pthread_handle handle;
417 ASSERT(th->p_exited);
418 /* Make the handle invalid */
419 handle = thread_handle(th->p_tid);
420 __pthread_lock(&handle->h_lock);
421 handle->h_descr = NULL;
422 handle->h_bottom = (char *)(-1L);
423 __pthread_unlock(&handle->h_lock);
424 #ifdef FREE_THREAD_SELF
425 FREE_THREAD_SELF(th, th->p_nr);
426 #endif
427 /* One fewer threads in __pthread_handles */
428 __pthread_handles_num--;
429 /* If initial thread, nothing to free */
430 if (th == &__pthread_initial_thread) return;
431 if (!th->p_userstack)
433 /* Free the stack and thread descriptor area */
434 if (th->p_guardsize != 0)
435 munmap(th->p_guardaddr, th->p_guardsize);
436 munmap((caddr_t) ((char *)(th+1) - STACK_SIZE), STACK_SIZE);
440 /* Handle threads that have exited */
442 static void pthread_exited(pid_t pid)
444 pthread_descr th;
445 int detached;
446 /* Find thread with that pid */
447 for (th = __pthread_main_thread->p_nextlive;
448 th != __pthread_main_thread;
449 th = th->p_nextlive) {
450 if (th->p_pid == pid) {
451 /* Remove thread from list of active threads */
452 th->p_nextlive->p_prevlive = th->p_prevlive;
453 th->p_prevlive->p_nextlive = th->p_nextlive;
454 /* Mark thread as exited, and if detached, free its resources */
455 __pthread_lock(th->p_lock);
456 th->p_exited = 1;
457 detached = th->p_detached;
458 __pthread_unlock(th->p_lock);
459 if (detached)
460 pthread_free(th);
461 break;
464 /* If all threads have exited and the main thread is pending on a
465 pthread_exit, wake up the main thread and terminate ourselves. */
466 if (main_thread_exiting &&
467 __pthread_main_thread->p_nextlive == __pthread_main_thread) {
468 restart(__pthread_main_thread);
469 _exit(0);
473 static void pthread_reap_children(void)
475 pid_t pid;
476 int status;
478 while ((pid = __libc_waitpid(-1, &status, WNOHANG | __WCLONE)) > 0) {
479 pthread_exited(pid);
480 if (WIFSIGNALED(status)) {
481 /* If a thread died due to a signal, send the same signal to
482 all other threads, including the main thread. */
483 pthread_kill_all_threads(WTERMSIG(status), 1);
484 _exit(0);
489 /* Try to free the resources of a thread when requested by pthread_join
490 or pthread_detach on a terminated thread. */
492 static void pthread_handle_free(pthread_t th_id)
494 pthread_handle handle = thread_handle(th_id);
495 pthread_descr th;
497 __pthread_lock(&handle->h_lock);
498 if (invalid_handle(handle, th_id)) {
499 /* pthread_reap_children has deallocated the thread already,
500 nothing needs to be done */
501 __pthread_unlock(&handle->h_lock);
502 return;
504 th = handle->h_descr;
505 if (th->p_exited) {
506 __pthread_unlock(&handle->h_lock);
507 pthread_free(th);
508 } else {
509 /* The Unix process of the thread is still running.
510 Mark the thread as detached so that the thread manager will
511 deallocate its resources when the Unix process exits. */
512 th->p_detached = 1;
513 __pthread_unlock(&handle->h_lock);
517 /* Send a signal to all running threads */
519 static void pthread_kill_all_threads(int sig, int main_thread_also)
521 pthread_descr th;
522 for (th = __pthread_main_thread->p_nextlive;
523 th != __pthread_main_thread;
524 th = th->p_nextlive) {
525 kill(th->p_pid, sig);
527 if (main_thread_also) {
528 kill(__pthread_main_thread->p_pid, sig);
532 /* Process-wide exit() */
534 static void pthread_handle_exit(pthread_descr issuing_thread, int exitcode)
536 pthread_descr th;
537 __pthread_exit_requested = 1;
538 __pthread_exit_code = exitcode;
539 /* Send the CANCEL signal to all running threads, including the main
540 thread, but excluding the thread from which the exit request originated
541 (that thread must complete the exit, e.g. calling atexit functions
542 and flushing stdio buffers). */
543 for (th = issuing_thread->p_nextlive;
544 th != issuing_thread;
545 th = th->p_nextlive) {
546 kill(th->p_pid, __pthread_sig_cancel);
548 /* Now, wait for all these threads, so that they don't become zombies
549 and their times are properly added to the thread manager's times. */
550 for (th = issuing_thread->p_nextlive;
551 th != issuing_thread;
552 th = th->p_nextlive) {
553 waitpid(th->p_pid, NULL, __WCLONE);
555 restart(issuing_thread);
556 _exit(0);
559 /* Handler for __pthread_sig_restart in thread manager thread */
561 void __pthread_manager_sighandler(int sig)
563 terminated_children = 1;
566 /* Adjust priority of thread manager so that it always run at a priority
567 higher than all threads */
569 void __pthread_manager_adjust_prio(int thread_prio)
571 struct sched_param param;
573 if (thread_prio <= __pthread_manager_thread.p_priority) return;
574 param.sched_priority =
575 thread_prio < __sched_get_priority_max(SCHED_FIFO)
576 ? thread_prio + 1 : thread_prio;
577 __sched_setscheduler(__pthread_manager_thread.p_pid, SCHED_FIFO, &param);
578 __pthread_manager_thread.p_priority = thread_prio;