1 #include "private/pthread_support.h"
3 #if defined(GC_PTHREADS) && !defined(GC_SOLARIS_THREADS) \
4 && !defined(GC_IRIX_THREADS) && !defined(GC_WIN32_THREADS) \
5 && !defined(GC_DARWIN_THREADS) && !defined(GC_AIX_THREADS)
16 # define NSIG (MAXSIG+1)
19 # elif defined(__SIGRTMAX)
20 # define NSIG (__SIGRTMAX+1)
26 void GC_print_sig_mask()
31 if (pthread_sigmask(SIG_BLOCK, NULL, &blocked) != 0)
32 ABORT("pthread_sigmask");
33 GC_printf0("Blocked: ");
34 for (i = 1; i < NSIG; i++) {
35 if (sigismember(&blocked, i)) { GC_printf1("%ld ",(long) i); }
42 /* Remove the signals that we want to allow in thread stopping */
43 /* handler from a set. */
44 void GC_remove_allowed_signals(sigset_t *set)
47 if (sigdelset(set, SIGINT) != 0
48 || sigdelset(set, SIGQUIT) != 0
49 || sigdelset(set, SIGABRT) != 0
50 || sigdelset(set, SIGTERM) != 0) {
51 ABORT("sigdelset() failed");
56 /* Handlers write to the thread structure, which is in the heap, */
57 /* and hence can trigger a protection fault. */
58 if (sigdelset(set, SIGSEGV) != 0
60 || sigdelset(set, SIGBUS) != 0
63 ABORT("sigdelset() failed");
68 static sigset_t suspend_handler_mask;
70 word GC_stop_count; /* Incremented at the beginning of GC_stop_world. */
72 #ifdef GC_OSF1_THREADS
73 GC_bool GC_retry_signals = TRUE;
75 GC_bool GC_retry_signals = FALSE;
79 * We use signals to stop threads during GC.
81 * Suspended threads wait in signal handler for SIG_THR_RESTART.
82 * That's more portable than semaphores or condition variables.
83 * (We do use sem_post from a signal handler, but that should be portable.)
85 * The thread suspension signal SIG_SUSPEND is now defined in gc_priv.h.
86 * Note that we can't just stop a thread; we need it to save its stack
87 * pointer(s) and acknowledge.
90 #ifndef SIG_THR_RESTART
91 # if defined(GC_HPUX_THREADS) || defined(GC_OSF1_THREADS)
93 # define SIG_THR_RESTART _SIGRTMIN + 5
95 # define SIG_THR_RESTART SIGRTMIN + 5
98 # define SIG_THR_RESTART SIGXCPU
102 sem_t GC_suspend_ack_sem;
104 static void _GC_suspend_handler(int sig)
107 pthread_t my_thread = pthread_self();
109 # ifdef PARALLEL_MARK
110 word my_mark_no = GC_mark_no;
111 /* Marker can't proceed until we acknowledge. Thus this is */
112 /* guaranteed to be the mark_no correspending to our */
113 /* suspension, i.e. the marker can't have incremented it yet. */
115 word my_stop_count = GC_stop_count;
117 if (sig != SIG_SUSPEND) ABORT("Bad signal in suspend_handler");
120 GC_printf1("Suspending 0x%lx\n", my_thread);
123 me = GC_lookup_thread(my_thread);
124 /* The lookup here is safe, since I'm doing this on behalf */
125 /* of a thread which holds the allocation lock in order */
126 /* to stop the world. Thus concurrent modification of the */
127 /* data structure is impossible. */
128 if (me -> stop_info.last_stop_count == my_stop_count) {
129 /* Duplicate signal. OK if we are retrying. */
130 if (!GC_retry_signals) {
131 WARN("Duplicate suspend signal in thread %lx\n",
137 me -> stop_info.stack_ptr = (ptr_t)GC_save_regs_in_stack();
139 me -> stop_info.stack_ptr = (ptr_t)(&dummy);
142 me -> backing_store_ptr = (ptr_t)GC_save_regs_in_stack();
145 /* Tell the thread that wants to stop the world that this */
146 /* thread has been stopped. Note that sem_post() is */
147 /* the only async-signal-safe primitive in LinuxThreads. */
148 sem_post(&GC_suspend_ack_sem);
149 me -> stop_info.last_stop_count = my_stop_count;
151 /* Wait until that thread tells us to restart by sending */
152 /* this thread a SIG_THR_RESTART signal. */
153 /* SIG_THR_RESTART should be masked at this point. Thus there */
156 me->stop_info.signal = 0;
157 sigsuspend(&suspend_handler_mask); /* Wait for signal */
158 } while (me->stop_info.signal != SIG_THR_RESTART);
159 /* If the RESTART signal gets lost, we can still lose. That should be */
160 /* less likely than losing the SUSPEND signal, since we don't do much */
161 /* between the sem_post and sigsuspend. */
162 /* We'd need more handshaking to work around that, since we don't want */
163 /* to accidentally leave a RESTART signal pending, thus causing us to */
164 /* continue prematurely in a future round. */
166 /* Tell the thread that wants to start the world that this */
167 /* thread has been started. Note that sem_post() is */
168 /* the only async-signal-safe primitive in LinuxThreads. */
169 sem_post(&GC_suspend_ack_sem);
173 GC_printf1("Continuing 0x%lx\n", my_thread);
177 void GC_suspend_handler(int sig)
179 int old_errno = errno;
180 _GC_suspend_handler(sig);
184 static void _GC_restart_handler(int sig)
186 pthread_t my_thread = pthread_self();
189 if (sig != SIG_THR_RESTART) ABORT("Bad signal in suspend_handler");
191 /* Let the GC_suspend_handler() know that we got a SIG_THR_RESTART. */
192 /* The lookup here is safe, since I'm doing this on behalf */
193 /* of a thread which holds the allocation lock in order */
194 /* to stop the world. Thus concurrent modification of the */
195 /* data structure is impossible. */
196 me = GC_lookup_thread(my_thread);
197 me->stop_info.signal = SIG_THR_RESTART;
200 ** Note: even if we didn't do anything useful here,
201 ** it would still be necessary to have a signal handler,
202 ** rather than ignoring the signals, otherwise
203 ** the signals will not be delivered at all, and
204 ** will thus not interrupt the sigsuspend() above.
208 GC_printf1("In GC_restart_handler for 0x%lx\n", pthread_self());
213 # define IF_IA64(x) x
217 /* We hold allocation lock. Should do exactly the right thing if the */
218 /* world is stopped. Should not fail if it isn't. */
219 static void pthread_push_all_stacks()
221 GC_bool found_me = FALSE;
225 /* On IA64, we also need to scan the register backing store. */
226 IF_IA64(ptr_t bs_lo; ptr_t bs_hi;)
227 pthread_t me = pthread_self();
229 if (!GC_thr_initialized) GC_thr_init();
231 GC_printf1("Pushing stacks from thread 0x%lx\n", (unsigned long) me);
233 for (i = 0; i < THREAD_TABLE_SZ; i++) {
234 for (p = GC_threads[i]; p != 0; p = p -> next) {
235 if (p -> flags & FINISHED) continue;
236 if (pthread_equal(p -> id, me)) {
238 lo = (ptr_t)GC_save_regs_in_stack();
243 IF_IA64(bs_hi = (ptr_t)GC_save_regs_in_stack();)
245 lo = p -> stop_info.stack_ptr;
246 IF_IA64(bs_hi = p -> backing_store_ptr;)
248 if ((p -> flags & MAIN_THREAD) == 0) {
250 IF_IA64(bs_lo = p -> backing_store_end);
252 /* The original stack. */
254 IF_IA64(bs_lo = BACKING_STORE_BASE;)
257 GC_printf3("Stack for thread 0x%lx = [%lx,%lx)\n",
258 (unsigned long) p -> id,
259 (unsigned long) lo, (unsigned long) hi);
261 if (0 == lo) ABORT("GC_push_all_stacks: sp not set!\n");
262 # ifdef STACK_GROWS_UP
263 /* We got them backwards! */
264 GC_push_all_stack(hi, lo);
266 GC_push_all_stack(lo, hi);
270 GC_printf3("Reg stack for thread 0x%lx = [%lx,%lx)\n",
271 (unsigned long) p -> id,
272 (unsigned long) bs_lo, (unsigned long) bs_hi);
274 if (pthread_equal(p -> id, me)) {
275 GC_push_all_eager(bs_lo, bs_hi);
277 GC_push_all_stack(bs_lo, bs_hi);
282 if (!found_me && !GC_in_thread_creation)
283 ABORT("Collecting from unknown thread.");
286 void GC_restart_handler(int sig)
288 int old_errno = errno;
289 _GC_restart_handler (sig);
293 /* We hold allocation lock. Should do exactly the right thing if the */
294 /* world is stopped. Should not fail if it isn't. */
295 void GC_push_all_stacks()
297 pthread_push_all_stacks();
300 /* There seems to be a very rare thread stopping problem. To help us */
301 /* debug that, we save the ids of the stopping thread. */
302 pthread_t GC_stopping_thread;
305 /* We hold the allocation lock. Suspend all threads that might */
306 /* still be running. Return the number of suspend signals that */
310 int n_live_threads = 0;
314 pthread_t my_thread = pthread_self();
316 GC_stopping_thread = my_thread; /* debugging only. */
317 GC_stopping_pid = getpid(); /* debugging only. */
318 for (i = 0; i < THREAD_TABLE_SZ; i++) {
319 for (p = GC_threads[i]; p != 0; p = p -> next) {
320 if (p -> id != my_thread) {
321 if (p -> flags & FINISHED) continue;
322 if (p -> stop_info.last_stop_count == GC_stop_count) continue;
323 if (p -> thread_blocked) /* Will wait */ continue;
326 GC_printf1("Sending suspend signal to 0x%lx\n", p -> id);
329 result = pthread_kill(p -> id, SIG_SUSPEND);
332 /* Not really there anymore. Possible? */
338 ABORT("pthread_kill failed");
343 return n_live_threads;
346 /* Caller holds allocation lock. */
347 static void pthread_stop_world()
354 GC_printf1("Stopping the world from 0x%lx\n", pthread_self());
357 n_live_threads = GC_suspend_all();
359 if (GC_retry_signals) {
360 unsigned long wait_usecs = 0; /* Total wait since retry. */
361 # define WAIT_UNIT 3000
362 # define RETRY_INTERVAL 100000
366 sem_getvalue(&GC_suspend_ack_sem, &ack_count);
367 if (ack_count == n_live_threads) break;
368 if (wait_usecs > RETRY_INTERVAL) {
369 int newly_sent = GC_suspend_all();
372 if (GC_print_stats) {
373 GC_printf1("Resent %ld signals after timeout\n",
377 sem_getvalue(&GC_suspend_ack_sem, &ack_count);
378 if (newly_sent < n_live_threads - ack_count) {
379 WARN("Lost some threads during GC_stop_world?!\n",0);
380 n_live_threads = ack_count + newly_sent;
385 wait_usecs += WAIT_UNIT;
388 for (i = 0; i < n_live_threads; i++) {
389 while (0 != (code = sem_wait(&GC_suspend_ack_sem))) {
390 if (errno != EINTR) {
391 GC_err_printf1("Sem_wait returned %ld\n", (unsigned long)code);
392 ABORT("sem_wait for handler failed");
397 GC_printf1("World stopped from 0x%lx\n", pthread_self());
399 GC_stopping_thread = 0; /* debugging only */
402 /* Caller holds allocation lock. */
405 /* Make sure all free list construction has stopped before we start. */
406 /* No new construction can start, since free list construction is */
407 /* required to acquire and release the GC lock before it starts, */
408 /* and we have the lock. */
409 # ifdef PARALLEL_MARK
410 GC_acquire_mark_lock();
411 GC_ASSERT(GC_fl_builder_count == 0);
412 /* We should have previously waited for it to become zero. */
413 # endif /* PARALLEL_MARK */
415 if (gc_thread_vtable && gc_thread_vtable->stop_world)
416 gc_thread_vtable->stop_world ();
418 pthread_stop_world ();
419 # ifdef PARALLEL_MARK
420 GC_release_mark_lock();
424 /* Caller holds allocation lock, and has held it continuously since */
425 /* the world stopped. */
426 static void pthread_start_world()
428 pthread_t my_thread = pthread_self();
430 register GC_thread p;
431 register int n_live_threads = 0;
436 GC_printf0("World starting\n");
439 for (i = 0; i < THREAD_TABLE_SZ; i++) {
440 for (p = GC_threads[i]; p != 0; p = p -> next) {
441 if (p -> id != my_thread) {
442 if (p -> flags & FINISHED) continue;
443 if (p -> thread_blocked) continue;
446 GC_printf1("Sending restart signal to 0x%lx\n", p -> id);
449 result = pthread_kill(p -> id, SIG_THR_RESTART);
452 /* Not really there anymore. Possible? */
458 ABORT("pthread_kill failed");
465 GC_printf0 ("All threads signaled");
468 for (i = 0; i < n_live_threads; i++) {
469 while (0 != (code = sem_wait(&GC_suspend_ack_sem))) {
470 if (errno != EINTR) {
471 GC_err_printf1("Sem_wait returned %ld\n", (unsigned long)code);
472 ABORT("sem_wait for handler failed");
478 GC_printf0("World started\n");
482 void GC_start_world()
484 if (gc_thread_vtable && gc_thread_vtable->start_world)
485 gc_thread_vtable->start_world();
487 pthread_start_world ();
490 static void pthread_stop_init() {
491 struct sigaction act;
493 if (sem_init(&GC_suspend_ack_sem, 0, 0) != 0)
494 ABORT("sem_init failed");
496 act.sa_flags = SA_RESTART;
497 if (sigfillset(&act.sa_mask) != 0) {
498 ABORT("sigfillset() failed");
500 GC_remove_allowed_signals(&act.sa_mask);
501 /* SIG_THR_RESTART is set in the resulting mask. */
502 /* It is unmasked by the handler when necessary. */
503 act.sa_handler = GC_suspend_handler;
504 if (sigaction(SIG_SUSPEND, &act, NULL) != 0) {
505 ABORT("Cannot set SIG_SUSPEND handler");
508 act.sa_handler = GC_restart_handler;
509 if (sigaction(SIG_THR_RESTART, &act, NULL) != 0) {
510 ABORT("Cannot set SIG_THR_RESTART handler");
513 /* Inititialize suspend_handler_mask. It excludes SIG_THR_RESTART. */
514 if (sigfillset(&suspend_handler_mask) != 0) ABORT("sigfillset() failed");
515 GC_remove_allowed_signals(&suspend_handler_mask);
516 if (sigdelset(&suspend_handler_mask, SIG_THR_RESTART) != 0)
517 ABORT("sigdelset() failed");
519 /* Check for GC_RETRY_SIGNALS. */
520 if (0 != GETENV("GC_RETRY_SIGNALS")) {
521 GC_retry_signals = TRUE;
523 if (0 != GETENV("GC_NO_RETRY_SIGNALS")) {
524 GC_retry_signals = FALSE;
527 if (GC_print_stats && GC_retry_signals) {
528 GC_printf0("Will retry suspend signal if necessary.\n");
533 /* We hold the allocation lock. */
536 if (gc_thread_vtable && gc_thread_vtable->initialize)
537 gc_thread_vtable->initialize ();
539 pthread_stop_init ();
542 GCThreadFunctions *gc_thread_vtable = NULL;
545 GC_mono_debugger_add_all_threads (void)
550 if (gc_thread_vtable && gc_thread_vtable->thread_created) {
551 for (i = 0; i < THREAD_TABLE_SZ; i++) {
552 for (p = GC_threads[i]; p != 0; p = p -> next) {
553 gc_thread_vtable->thread_created (p->id, &p->stop_info.stack_ptr);