0.8.4.10

[sbcl.git] / src / runtime / thread.c

diff --git a/src/runtime/thread.c b/src/runtime/thread.c
index eb8f241..206511a 100644 (file)
--- a/src/runtime/thread.c
+++ b/src/runtime/thread.c
@@ -24,7 +24,7 @@
 
 int dynamic_values_bytes=4096*sizeof(lispobj); /* same for all threads */
 struct thread *all_threads;
-lispobj all_threads_lock;
+volatile lispobj all_threads_lock;
 volatile int countdown_to_gc;
 extern struct interrupt_data * global_interrupt_data;
 
@@ -139,6 +139,7 @@ pid_t create_thread(lispobj initial_function) {
     th->binding_stack_pointer=th->binding_stack_start;
     th->this=th;
     th->pid=0;
+    th->state=STATE_RUNNING;
 #ifdef LISP_FEATURE_STACK_GROWS_DOWNWARD_NOT_UPWARD
     th->alien_stack_pointer=((void *)th->alien_stack_start
                             + ALIEN_STACK_SIZE-4); /* naked 4.  FIXME */
@@ -238,6 +239,7 @@ void destroy_thread (struct thread *th)
 #endif
     get_spinlock(&all_threads_lock,th->pid);
     if(countdown_to_gc>0) countdown_to_gc--;
+    th->state=STATE_STOPPED;
     if(th==all_threads) 
        all_threads=th->next;
     else {
@@ -263,6 +265,10 @@ struct thread *find_thread_by_pid(pid_t pid)
     return 0;
 }
 
+/* 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. */
+#if defined LISP_FEATURE_SB_THREAD
 void block_sigcont(void)
 {
     /* don't allow ourselves to receive SIGCONT while we're in the
@@ -274,10 +280,6 @@ void block_sigcont(void)
     sigprocmask(SIG_BLOCK, &newset, 0); 
 }
 
-/* This is 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. */
-#if defined LISP_FEATURE_SB_THREAD
 void unblock_sigcont_and_sleep(void)
 {
     sigset_t set;
@@ -321,8 +323,21 @@ void gc_stop_the_world()
             * for them on each time around */
            for(p=all_threads;p!=tail;p=p->next) {
                if(p==th) continue;
-               countdown_to_gc++;
-               kill(p->pid,SIG_STOP_FOR_GC);
+               /* if the head of all_threads is removed during
+                * gc_stop_the_world, we may take a second trip through the 
+                * list and end up counting twice as many threads to wait for
+                * as actually exist */
+               if(p->state!=STATE_RUNNING) continue;
+               countdown_to_gc++;
+               p->state=STATE_STOPPING;
+               /* Note no return value check from kill().  If the
+                * thread had been reaped already, we kill it and
+                * increment countdown_to_gc anyway.  This is to avoid
+                * complicating the logic in destroy_thread, which would 
+                * otherwise have to know whether the thread died before or
+                * after it was killed
+                */
+               kill(p->pid,SIG_STOP_FOR_GC);
            }
            tail=all_threads;
        } else {
@@ -339,6 +354,7 @@ void gc_start_the_world()
     get_spinlock(&all_threads_lock,th->pid);
     for(p=all_threads;p;p=p->next) {
        if(p==th) continue;
+       p->state=STATE_RUNNING;
        kill(p->pid,SIGCONT);
     }
     release_spinlock(&all_threads_lock);