diff options
| -rw-r--r-- | pthread_stop_world.c | 104 |
1 files changed, 58 insertions, 46 deletions
diff --git a/pthread_stop_world.c b/pthread_stop_world.c index d8aee014..ad1be33f 100644 --- a/pthread_stop_world.c +++ b/pthread_stop_world.c @@ -134,14 +134,15 @@ static sigset_t suspend_handler_mask; STATIC volatile AO_t GC_stop_count; /* Incremented (to the nearest even value) at */ - /* the beginning of GC_stop_world() and once */ - /* more (to an odd value) at the beginning of */ - /* GC_start_world(). The lowest bit is */ - /* THREAD_RESTARTED one which, if set, means */ - /* it is safe for threads to restart, */ - /* i.e. they will see another suspend signal */ - /* before they are expected to stop (unless */ - /* they have stopped voluntarily). */ + /* the beginning of GC_stop_world() (or when */ + /* a thread is requested to be suspended by */ + /* GC_suspend_thread) and once more (to an odd */ + /* value) at the beginning of GC_start_world(). */ + /* The lowest bit is THREAD_RESTARTED one */ + /* which, if set, means it is safe for threads */ + /* to restart, i.e. they will see another */ + /* suspend signal before they are expected to */ + /* stop (unless they have stopped voluntarily). */ STATIC GC_bool GC_retry_signals = FALSE; @@ -355,32 +356,6 @@ STATIC void GC_suspend_handler_inner(ptr_t dummy GC_ATTR_UNUSED, GC_log_printf("Suspending %p\n", (void *)self); # endif me = GC_lookup_thread_async(self); - -# ifdef GC_ENABLE_SUSPEND_THREAD - suspend_cnt = (word)ao_load_async(&(me -> stop_info.ext_suspend_cnt)); - if ((suspend_cnt & 1) != 0) { - GC_store_stack_ptr(me); -# ifdef E2K - GC_ASSERT(NULL == me -> backing_store_end); - GET_PROCEDURE_STACK_LOCAL(&bs_lo, &stack_size); - me -> backing_store_end = bs_lo; - me -> backing_store_ptr = bs_lo + stack_size; -# endif - sem_post(&GC_suspend_ack_sem); - GC_suspend_self_inner(me, suspend_cnt); -# ifdef DEBUG_THREADS - GC_log_printf("Continuing %p on GC_resume_thread\n", (void *)self); -# endif -# ifdef E2K - FREE_PROCEDURE_STACK_LOCAL(bs_lo, stack_size); - me -> backing_store_ptr = NULL; - me -> backing_store_end = NULL; -# endif - RESTORE_CANCEL(cancel_state); - return; - } -# endif - if ((me->stop_info.last_stop_count & ~(word)THREAD_RESTARTED) == my_stop_count) { /* Duplicate signal. OK if we are retrying. */ @@ -397,6 +372,9 @@ STATIC void GC_suspend_handler_inner(ptr_t dummy GC_ATTR_UNUSED, me -> backing_store_end = bs_lo; me -> backing_store_ptr = bs_lo + stack_size; # endif +# ifdef GC_ENABLE_SUSPEND_THREAD + suspend_cnt = (word)ao_load_async(&(me -> stop_info.ext_suspend_cnt)); +# endif /* Tell the thread that wants to stop the world that this */ /* thread has been stopped. Note that sem_post() is */ @@ -416,8 +394,14 @@ STATIC void GC_suspend_handler_inner(ptr_t dummy GC_ATTR_UNUSED, /* this code should not be executed. */ do { sigsuspend(&suspend_handler_mask); - } while (ao_load_acquire_async(&GC_stop_count) == my_stop_count); - /* iterate while not restarting the world */ + /* Iterate while not restarting the world or thread is suspended. */ + } while (ao_load_acquire_async(&GC_stop_count) == my_stop_count +# ifdef GC_ENABLE_SUSPEND_THREAD + || ((suspend_cnt & 1) != 0 + && (word)ao_load_acquire_async( + &(me -> stop_info.ext_suspend_cnt)) == suspend_cnt) +# endif + ); # ifdef DEBUG_THREADS GC_log_printf("Continuing %p\n", (void *)self); @@ -629,17 +613,27 @@ STATIC void GC_restart_handler(int sig) } GC_INNER void GC_suspend_self_inner(GC_thread me, word suspend_cnt) { + IF_CANCEL(int cancel_state;) + GC_ASSERT((suspend_cnt & 1) != 0); + DISABLE_CANCEL(cancel_state); +# ifdef DEBUG_THREADS + GC_log_printf("Suspend self: %p\n", (void *)(me -> id)); +# endif while ((word)ao_load_acquire_async(&(me -> stop_info.ext_suspend_cnt)) == suspend_cnt) { - /* TODO: Use sigsuspend() instead. */ + /* TODO: Use sigsuspend() even for self-suspended threads. */ GC_brief_async_signal_safe_sleep(); } +# ifdef DEBUG_THREADS + GC_log_printf("Resume self: %p\n", (void *)(me -> id)); +# endif + RESTORE_CANCEL(cancel_state); } GC_API void GC_CALL GC_suspend_thread(GC_SUSPEND_THREAD_ID thread) { GC_thread t; - AO_t saved_stop_count; + AO_t next_stop_count; word suspend_cnt; IF_CANCEL(int cancel_state;) DCL_LOCK_STATE; @@ -652,6 +646,7 @@ STATIC void GC_restart_handler(int sig) } suspend_cnt = (word)(t -> stop_info.ext_suspend_cnt); if ((suspend_cnt & 1) != 0) /* already suspended? */ { + GC_ASSERT(!THREAD_EQUAL((pthread_t)thread, pthread_self())); UNLOCK(); return; } @@ -691,9 +686,9 @@ STATIC void GC_restart_handler(int sig) /* be trying to acquire this lock too, and the suspend handler */ /* execution is deferred until the write fault handler completes. */ - saved_stop_count = GC_stop_count; - GC_ASSERT((saved_stop_count & THREAD_RESTARTED) != 0); - AO_store(&GC_stop_count, saved_stop_count + THREAD_RESTARTED); + next_stop_count = GC_stop_count + THREAD_RESTARTED; + GC_ASSERT((next_stop_count & THREAD_RESTARTED) == 0); + AO_store(&GC_stop_count, next_stop_count); /* Set the flag making the change visible to the signal handler. */ AO_store_release(&(t -> stop_info.ext_suspend_cnt), @@ -711,13 +706,10 @@ STATIC void GC_restart_handler(int sig) /* Wait for the thread to complete threads table lookup and */ /* stack_ptr assignment. */ GC_ASSERT(GC_thr_initialized); - while (sem_wait(&GC_suspend_ack_sem) != 0) { - if (errno != EINTR) - ABORT("sem_wait for handler failed (suspend_self)"); - } + suspend_restart_barrier(1); if (GC_manual_vdb) GC_release_dirty_lock(); - AO_store(&GC_stop_count, saved_stop_count); /* restore the counter */ + AO_store(&GC_stop_count, next_stop_count | THREAD_RESTARTED); RESTORE_CANCEL(cancel_state); UNLOCK(); @@ -733,8 +725,28 @@ STATIC void GC_restart_handler(int sig) word suspend_cnt = (word)(t -> stop_info.ext_suspend_cnt); if ((suspend_cnt & 1) != 0) /* is suspended? */ { + GC_ASSERT((GC_stop_count & THREAD_RESTARTED) != 0); /* Mark the thread as not suspended - it will be resumed shortly. */ AO_store(&(t -> stop_info.ext_suspend_cnt), (AO_t)(suspend_cnt + 1)); + + if ((t -> flags & (FINISHED | DO_BLOCKING)) == 0) { + int result = raise_signal(t, GC_sig_thr_restart); + + /* TODO: Support signal resending on GC_retry_signals */ + if (result != 0) + ABORT_ARG1("pthread_kill failed in GC_resume_thread", + ": errcode= %d", result); +# ifndef GC_NETBSD_THREADS_WORKAROUND + if (GC_retry_signals || GC_sig_suspend == GC_sig_thr_restart) +# endif + { + IF_CANCEL(int cancel_state;) + + DISABLE_CANCEL(cancel_state); + suspend_restart_barrier(1); + RESTORE_CANCEL(cancel_state); + } + } } } UNLOCK(); |