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 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. */
167 GC_printf1("Continuing 0x%lx\n", my_thread);
171 void GC_restart_handler(int sig)
173 pthread_t my_thread = pthread_self();
176 if (sig != SIG_THR_RESTART) ABORT("Bad signal in suspend_handler");
178 /* Let the GC_suspend_handler() know that we got a SIG_THR_RESTART. */
179 /* The lookup here is safe, since I'm doing this on behalf */
180 /* of a thread which holds the allocation lock in order */
181 /* to stop the world. Thus concurrent modification of the */
182 /* data structure is impossible. */
183 me = GC_lookup_thread(my_thread);
184 me->stop_info.signal = SIG_THR_RESTART;
187 ** Note: even if we didn't do anything useful here,
188 ** it would still be necessary to have a signal handler,
189 ** rather than ignoring the signals, otherwise
190 ** the signals will not be delivered at all, and
191 ** will thus not interrupt the sigsuspend() above.
195 GC_printf1("In GC_restart_handler for 0x%lx\n", pthread_self());
200 # define IF_IA64(x) x
204 /* We hold allocation lock. Should do exactly the right thing if the */
205 /* world is stopped. Should not fail if it isn't. */
206 static void pthread_push_all_stacks()
208 GC_bool found_me = FALSE;
212 /* On IA64, we also need to scan the register backing store. */
213 IF_IA64(ptr_t bs_lo; ptr_t bs_hi;)
214 pthread_t me = pthread_self();
216 if (!GC_thr_initialized) GC_thr_init();
218 GC_printf1("Pushing stacks from thread 0x%lx\n", (unsigned long) me);
220 for (i = 0; i < THREAD_TABLE_SZ; i++) {
221 for (p = GC_threads[i]; p != 0; p = p -> next) {
222 if (p -> flags & FINISHED) continue;
223 if (pthread_equal(p -> id, me)) {
225 lo = (ptr_t)GC_save_regs_in_stack();
230 IF_IA64(bs_hi = (ptr_t)GC_save_regs_in_stack();)
232 lo = p -> stop_info.stack_ptr;
233 IF_IA64(bs_hi = p -> backing_store_ptr;)
235 if ((p -> flags & MAIN_THREAD) == 0) {
237 IF_IA64(bs_lo = p -> backing_store_end);
239 /* The original stack. */
241 IF_IA64(bs_lo = BACKING_STORE_BASE;)
244 GC_printf3("Stack for thread 0x%lx = [%lx,%lx)\n",
245 (unsigned long) p -> id,
246 (unsigned long) lo, (unsigned long) hi);
248 if (0 == lo) ABORT("GC_push_all_stacks: sp not set!\n");
249 # ifdef STACK_GROWS_UP
250 /* We got them backwards! */
251 GC_push_all_stack(hi, lo);
253 GC_push_all_stack(lo, hi);
257 GC_printf3("Reg stack for thread 0x%lx = [%lx,%lx)\n",
258 (unsigned long) p -> id,
259 (unsigned long) bs_lo, (unsigned long) bs_hi);
261 if (pthread_equal(p -> id, me)) {
262 GC_push_all_eager(bs_lo, bs_hi);
264 GC_push_all_stack(bs_lo, bs_hi);
269 if (!found_me && !GC_in_thread_creation)
270 ABORT("Collecting from unknown thread.");
273 /* We hold allocation lock. Should do exactly the right thing if the */
274 /* world is stopped. Should not fail if it isn't. */
275 void GC_push_all_stacks()
277 gc_thread_vtable->push_all_stacks();
280 /* There seems to be a very rare thread stopping problem. To help us */
281 /* debug that, we save the ids of the stopping thread. */
282 pthread_t GC_stopping_thread;
285 /* We hold the allocation lock. Suspend all threads that might */
286 /* still be running. Return the number of suspend signals that */
290 int n_live_threads = 0;
294 pthread_t my_thread = pthread_self();
296 GC_stopping_thread = my_thread; /* debugging only. */
297 GC_stopping_pid = getpid(); /* debugging only. */
298 for (i = 0; i < THREAD_TABLE_SZ; i++) {
299 for (p = GC_threads[i]; p != 0; p = p -> next) {
300 if (p -> id != my_thread) {
301 if (p -> flags & FINISHED) continue;
302 if (p -> stop_info.last_stop_count == GC_stop_count) continue;
303 if (p -> thread_blocked) /* Will wait */ continue;
306 GC_printf1("Sending suspend signal to 0x%lx\n", p -> id);
309 result = pthread_kill(p -> id, SIG_SUSPEND);
312 /* Not really there anymore. Possible? */
318 ABORT("pthread_kill failed");
323 return n_live_threads;
326 /* Caller holds allocation lock. */
327 static void pthread_stop_world()
334 GC_printf1("Stopping the world from 0x%lx\n", pthread_self());
337 n_live_threads = GC_suspend_all();
339 if (GC_retry_signals) {
340 unsigned long wait_usecs = 0; /* Total wait since retry. */
341 # define WAIT_UNIT 3000
342 # define RETRY_INTERVAL 100000
346 sem_getvalue(&GC_suspend_ack_sem, &ack_count);
347 if (ack_count == n_live_threads) break;
348 if (wait_usecs > RETRY_INTERVAL) {
349 int newly_sent = GC_suspend_all();
352 if (GC_print_stats) {
353 GC_printf1("Resent %ld signals after timeout\n",
357 sem_getvalue(&GC_suspend_ack_sem, &ack_count);
358 if (newly_sent < n_live_threads - ack_count) {
359 WARN("Lost some threads during GC_stop_world?!\n",0);
360 n_live_threads = ack_count + newly_sent;
365 wait_usecs += WAIT_UNIT;
368 for (i = 0; i < n_live_threads; i++) {
369 while (0 != (code = sem_wait(&GC_suspend_ack_sem))) {
370 if (errno != EINTR) {
371 GC_err_printf1("Sem_wait returned %ld\n", (unsigned long)code);
372 ABORT("sem_wait for handler failed");
377 GC_printf1("World stopped from 0x%lx\n", pthread_self());
379 GC_stopping_thread = 0; /* debugging only */
382 /* Caller holds allocation lock. */
385 /* Make sure all free list construction has stopped before we start. */
386 /* No new construction can start, since free list construction is */
387 /* required to acquire and release the GC lock before it starts, */
388 /* and we have the lock. */
389 # ifdef PARALLEL_MARK
390 GC_acquire_mark_lock();
391 GC_ASSERT(GC_fl_builder_count == 0);
392 /* We should have previously waited for it to become zero. */
393 # endif /* PARALLEL_MARK */
395 gc_thread_vtable->stop_world ();
396 # ifdef PARALLEL_MARK
397 GC_release_mark_lock();
401 /* Caller holds allocation lock, and has held it continuously since */
402 /* the world stopped. */
403 static void pthread_start_world()
405 pthread_t my_thread = pthread_self();
407 register GC_thread p;
408 register int n_live_threads = 0;
412 GC_printf0("World starting\n");
415 for (i = 0; i < THREAD_TABLE_SZ; i++) {
416 for (p = GC_threads[i]; p != 0; p = p -> next) {
417 if (p -> id != my_thread) {
418 if (p -> flags & FINISHED) continue;
419 if (p -> thread_blocked) continue;
422 GC_printf1("Sending restart signal to 0x%lx\n", p -> id);
425 result = pthread_kill(p -> id, SIG_THR_RESTART);
428 /* Not really there anymore. Possible? */
434 ABORT("pthread_kill failed");
440 GC_printf0("World started\n");
444 void GC_start_world()
446 gc_thread_vtable->start_world();
449 static void pthread_stop_init() {
450 struct sigaction act;
452 if (sem_init(&GC_suspend_ack_sem, 0, 0) != 0)
453 ABORT("sem_init failed");
455 act.sa_flags = SA_RESTART;
456 if (sigfillset(&act.sa_mask) != 0) {
457 ABORT("sigfillset() failed");
459 GC_remove_allowed_signals(&act.sa_mask);
460 /* SIG_THR_RESTART is set in the resulting mask. */
461 /* It is unmasked by the handler when necessary. */
462 act.sa_handler = GC_suspend_handler;
463 if (sigaction(SIG_SUSPEND, &act, NULL) != 0) {
464 ABORT("Cannot set SIG_SUSPEND handler");
467 act.sa_handler = GC_restart_handler;
468 if (sigaction(SIG_THR_RESTART, &act, NULL) != 0) {
469 ABORT("Cannot set SIG_THR_RESTART handler");
472 /* Inititialize suspend_handler_mask. It excludes SIG_THR_RESTART. */
473 if (sigfillset(&suspend_handler_mask) != 0) ABORT("sigfillset() failed");
474 GC_remove_allowed_signals(&suspend_handler_mask);
475 if (sigdelset(&suspend_handler_mask, SIG_THR_RESTART) != 0)
476 ABORT("sigdelset() failed");
478 /* Check for GC_RETRY_SIGNALS. */
479 if (0 != GETENV("GC_RETRY_SIGNALS")) {
480 GC_retry_signals = TRUE;
482 if (0 != GETENV("GC_NO_RETRY_SIGNALS")) {
483 GC_retry_signals = FALSE;
486 if (GC_print_stats && GC_retry_signals) {
487 GC_printf0("Will retry suspend signal if necessary.\n");
492 /* We hold the allocation lock. */
495 gc_thread_vtable->initialize ();
499 * This is used by the Mono Debugger to stop/start the world.
501 GCThreadFunctions pthread_thread_vtable = {
505 pthread_push_all_stacks,
509 GCThreadFunctions *gc_thread_vtable = &pthread_thread_vtable;