int dynamic_values_bytes=4096*sizeof(lispobj); /* same for all threads */
struct thread *all_threads;
volatile lispobj all_threads_lock;
+volatile lispobj thread_start_lock;
extern struct interrupt_data * global_interrupt_data;
extern int linux_no_threads_p;
th->binding_stack_pointer=th->binding_stack_start;
th->this=th;
th->pid=0;
- th->state=STATE_STOPPED;
+ th->state=STATE_STARTING;
#ifdef LISP_FEATURE_STACK_GROWS_DOWNWARD_NOT_UPWARD
th->alien_stack_pointer=((void *)th->alien_stack_start
+ ALIEN_STACK_SIZE-N_WORD_BYTES);
* to ensure that we don't have >1 thread with pid=0 on the list at once
*/
protect_control_stack_guard_page(th->pid,1);
+ th->pid=kid_pid; /* child will not start until this is set */
release_spinlock(&all_threads_lock);
sigprocmask(SIG_SETMASK,&oldset,0);
- th->pid=kid_pid; /* child will not start until this is set */
}
void create_initial_thread(lispobj initial_function) {
if(linux_no_threads_p) return 0;
th=create_thread_struct(initial_function);
if(th==0) return 0;
+#ifdef QSHOW_SIGNALS
+ SHOW("create_thread:waiting on lock");
+#endif
+ get_spinlock(&thread_start_lock,arch_os_get_current_thread()->pid);
+#ifdef QSHOW_SIGNALS
+ SHOW("create_thread:got lock");
+#endif
kid_pid=clone(new_thread_trampoline,
(((void*)th->control_stack_start)+
THREAD_CONTROL_STACK_SIZE-16),
if(kid_pid>0) {
link_thread(th,kid_pid);
+ /* wait here until our thread is started: see new_thread_trampoline */
+ while(th->state==STATE_STARTING) sched_yield();
+ /* it's started and initialized, it's safe to gc */
+ release_spinlock(&thread_start_lock);
+#ifdef QSHOW_SIGNALS
+ SHOW("create_thread:released lock");
+#endif
return th->pid;
} else {
+ release_spinlock(&thread_start_lock);
+#ifdef QSHOW_SIGNALS
+ SHOW("create_thread:released lock(failure)");
+#endif
os_invalidate((os_vm_address_t) th->control_stack_start,
((sizeof (lispobj))
* (th->control_stack_end-th->control_stack_start)) +
}
}
-/* These are not needed unless #+SB-THREAD, and since sigwaitinfo()
- * doesn't seem to be easily available everywhere (OpenBSD...) it's
- * more trouble than it's worth to compile it when not needed. */
-void block_sigcont(void)
-{
- /* don't allow ourselves to receive SIGCONT while we're in the
- * "ambiguous" state of being on the queue but not actually stopped.
- */
- sigset_t newset;
- sigemptyset(&newset);
- sigaddset(&newset,SIG_DEQUEUE);
- sigprocmask(SIG_BLOCK, &newset, 0);
-}
-
-void unblock_sigcont_and_sleep(void)
-{
- sigset_t set;
- sigemptyset(&set);
- sigaddset(&set,SIG_DEQUEUE);
- do {
- errno=0;
- sigwaitinfo(&set,0);
- }while(errno==EINTR);
- sigprocmask(SIG_UNBLOCK,&set,0);
-}
-
int interrupt_thread(pid_t pid, lispobj function)
{
union sigval sigval;
/* stopping the world is a two-stage process. From this thread we signal
* all the others with SIG_STOP_FOR_GC. The handler for this signal does
* the usual pseudo-atomic checks (we don't want to stop a thread while
- * it's in the middle of allocation) then kills _itself_ with SIGSTOP.
+ * it's in the middle of allocation) then waits for another SIG_STOP_FOR_GC.
*/
void gc_stop_the_world()
{
- /* stop all other threads by sending them SIG_STOP_FOR_GC */
+#ifdef QSHOW_SIGNALS
+ SHOW("gc_stop_the_world:begin");
+#endif
struct thread *p,*th=arch_os_get_current_thread();
- pid_t old_pid;
- int finished;
- do {
- finished=1;
- for(p=all_threads,old_pid=p->pid; p; p=p->next) {
- if(p==th) continue;
- if(p->state==STATE_RUNNING) {
- p->state=STATE_STOPPING;
- if(kill(p->pid,SIG_STOP_FOR_GC)==-1) {
- /* we can't kill the process; assume because it
- * died already (and its parent is dead so never
- * saw the SIGCHLD) */
- p->state=STATE_DEAD;
- }
- }
- if((p->state!=STATE_STOPPED) &&
- (p->state!=STATE_DEAD)) {
- finished=0;
- }
- }
- if(old_pid!=all_threads->pid) {
- finished=0;
- }
- } while(!finished);
+ /* keep threads from starting while the world is stopped. */
+ get_spinlock(&thread_start_lock,th->pid);
+#ifdef QSHOW_SIGNALS
+ SHOW("gc_stop_the_world:locked");
+#endif
+ /* stop all other threads by sending them SIG_STOP_FOR_GC */
+ for(p=all_threads; p; p=p->next) {
+ if((p!=th) && (p->pid!=0) && (p->state==STATE_RUNNING)) {
+ p->state=STATE_STOPPING;
+ if(kill(p->pid,SIG_STOP_FOR_GC)==-1) {
+ /* we can't kill the process; assume because it
+ * died already (and its parent is dead so never
+ * saw the SIGCHLD) */
+ p->state=STATE_DEAD;
+ }
+ }
+ }
+#ifdef QSHOW_SIGNALS
+ SHOW("gc_stop_the_world:signals sent");
+#endif
+ /* wait for the running threads to stop */
+ for(p=all_threads;p;) {
+ if((p==th) || (p->pid==0) || (p->state==STATE_STARTING) ||
+ (p->state==STATE_DEAD) || (p->state==STATE_STOPPED)) {
+ p=p->next;
+ }
+ }
+#ifdef QSHOW_SIGNALS
+ SHOW("gc_stop_the_world:end");
+#endif
}
void gc_start_the_world()
{
struct thread *p,*th=arch_os_get_current_thread();
/* if a resumed thread creates a new thread before we're done with
- * this loop, the new thread will get consed on the front of *
- * all_threads_lock, but it won't have been stopped so won't need
- * restarting */
+ * this loop, the new thread will get consed on the front of
+ * all_threads, but it won't have been stopped so won't need
+ * restarting; there can be threads just starting from before
+ * gc_stop_the_world, though */
+#ifdef QSHOW_SIGNALS
+ SHOW("gc_start_the_world:begin");
+#endif
for(p=all_threads;p;p=p->next) {
- if((p==th) || (p->state==STATE_DEAD)) continue;
- p->state=STATE_RUNNING;
- kill(p->pid,SIG_STOP_FOR_GC);
+ if((p!=th) && (p->pid!=0) && (p->state!=STATE_STARTING) &&
+ (p->state!=STATE_DEAD)) {
+ if(p->state!=STATE_STOPPED) {
+ lose("gc_start_the_world: wrong thread state is %ld\n",
+ fixnum_value(p->state));
+ }
+ kill(p->pid,SIG_STOP_FOR_GC);
+ }
+ }
+ /* we must wait for all threads to leave stopped state else we
+ * risk signal accumulation and lose any meaning of
+ * thread->state */
+ for(p=all_threads;p;) {
+ gc_assert(p->state!=STATE_STOPPING);
+ if((p==th) || (p->pid==0) || (p->state!=STATE_STOPPED)) {
+ p=p->next;
+ }
}
+ release_spinlock(&thread_start_lock);
+#ifdef QSHOW_SIGNALS
+ SHOW("gc_start_the_world:end");
+#endif
}
#endif
projects / sbcl.git / blobdiff