Don't hold the active thread list lock when signaling the gc thread.

The dead list thread is sufficient for synchronization.

Retire the arch_id (ldt array slot) in the gc thread instead of the
doing it in the thread itself.

Approved by:	re/jhb

3 files changed, 21 insertions, 12 deletions

diff --git a/lib/libthr/thread/thr_exit.c b/lib/libthr/thread/thr_exit.c
index dd510b1..bea7874 100644
--- a/lib/libthr/thread/thr_exit.c
+++ b/lib/libthr/thread/thr_exit.c
@@ -173,28 +173,30 @@ retry:
 	PTHREAD_SET_STATE(curthread, PS_DEAD);
 	_thread_critical_exit(curthread);
 	
-	/*
-	 * Signal the garbage collector thread that there is something
-	 * to clean up.
-	 */
-	if (pthread_cond_signal(&_gc_cond) != 0)
-		PANIC("Cannot signal gc cond");
-
 	/* If we're the last thread, call it quits */
 	if (TAILQ_EMPTY(&_thread_list))
 		exitNow = 1;
 
 	THREAD_LIST_UNLOCK;
-	DEAD_LIST_UNLOCK;
+
+	/*
+	 * Signal the garbage collector thread that there is something
+	 * to clean up. But don't allow it to free the memory until after
+	 * it is retired by holding on to the dead list lock.
+	 */
+	if (pthread_cond_signal(&_gc_cond) != 0)
+		PANIC("Cannot signal gc cond");
 
 	if (exitNow)
 		exit(0);
 
+	DEAD_LIST_UNLOCK;
+
 	/*
-	 * Retire the architecture specific id so that it can be used for
-	 * new threads.
+	 * This function will not return unless we are the last
+	 * thread, which we can't be because we've already checked
+	 * for that.
 	 */
-	_retire_thread(curthread->arch_id);
 	_thr_exit();
 
 	/* This point should not be reached. */
diff --git a/lib/libthr/thread/thr_gc.c b/lib/libthr/thread/thr_gc.c
index 9e26314..e2aa753 100644
--- a/lib/libthr/thread/thr_gc.c
+++ b/lib/libthr/thread/thr_gc.c
@@ -142,6 +142,13 @@ _thread_gc(pthread_addr_t arg)
 			pthread_cln = pthread;
 
 			_SPINUNLOCK(&pthread->lock);
+
+			/*
+		 	 * Retire the architecture specific id so it may be
+		 	 * used for new threads.
+			 */
+			_retire_thread(pthread_cln->arch_id);
+
 		}
 
 		/*
diff --git a/lib/libthr/thread/thr_join.c b/lib/libthr/thread/thr_join.c
index 88a71f2..2a5433a 100644
--- a/lib/libthr/thread/thr_join.c
+++ b/lib/libthr/thread/thr_join.c
@@ -160,9 +160,9 @@ _pthread_join(pthread_t pthread, void **thread_return)
 		/* Make the thread collectable by the garbage collector. */
 		pthread->attr.flags |= PTHREAD_DETACHED;
 		_SPINUNLOCK(&pthread->lock);
+		THREAD_LIST_UNLOCK;
 		if (pthread_cond_signal(&_gc_cond) != 0)
 			PANIC("Cannot signal gc cond");
-		THREAD_LIST_UNLOCK;
 		DEAD_LIST_UNLOCK;
 	}