From b1085cd3faf95cd4c02476f0bbda28ce692bb0e5 Mon Sep 17 00:00:00 2001
From: David Xu <davidxu@dragonflybsd.org>
Date: Thu, 24 Mar 2005 12:38:39 +0000
Subject: [PATCH] tcb is now managed by rtld, caching it is not correct,
 otherwise we may get stale copy of tls data from previous dead thread,
 caching should be done in rtld if needed.

---
 lib/libthread_xu/thread/thr_list.c | 61 +++++++++++++++++-------------
 1 file changed, 35 insertions(+), 26 deletions(-)

diff --git a/lib/libthread_xu/thread/thr_list.c b/lib/libthread_xu/thread/thr_list.c
index 0483717e37..7520951a3b 100644
--- a/lib/libthread_xu/thread/thr_list.c
+++ b/lib/libthread_xu/thread/thr_list.c
@@ -24,7 +24,7 @@
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  *
- * $DragonFly: src/lib/libthread_xu/thread/thr_list.c,v 1.1 2005/02/01 12:38:27 davidxu Exp $
+ * $DragonFly: src/lib/libthread_xu/thread/thr_list.c,v 1.2 2005/03/24 12:38:39 davidxu Exp $
  */
 
 #include <sys/cdefs.h>
@@ -140,7 +140,7 @@ struct pthread *
 _thr_alloc(struct pthread *curthread)
 {
 	struct pthread	*thread = NULL;
-	struct tcb	*tcb = NULL;
+	struct tcb	*tcb;
 
 	if (curthread != NULL) {
 		if (GC_NEEDED())
@@ -149,29 +149,29 @@ _thr_alloc(struct pthread *curthread)
 			THR_LOCK_ACQUIRE(curthread, &free_thread_lock);
 			if ((thread = TAILQ_FIRST(&free_threadq)) != NULL) {
 				TAILQ_REMOVE(&free_threadq, thread, tle);
-				tcb = thread->tcb;
 				free_thread_count--;
 			}
 			THR_LOCK_RELEASE(curthread, &free_thread_lock);
 		}
 	}
-	if ((thread == NULL) &&
-	    ((thread = malloc(sizeof(struct pthread))) != NULL)) {
-		if (curthread) {
-			THR_LOCK_ACQUIRE(curthread, &tcb_lock);
-			tcb = _tcb_ctor(thread, 0 /* not initial tls */);
-			THR_LOCK_RELEASE(curthread, &tcb_lock);
-		} else {
-			tcb = _tcb_ctor(thread, 1 /* initial tls */);
-		}
-		if (tcb == NULL) {
-			free(thread);
-			thread = NULL;
-		}
+	if (thread == NULL) {
+		thread = malloc(sizeof(struct pthread));
+		if (thread == NULL)
+			return (NULL);
+	}
+	if (curthread != NULL) {
+		THR_LOCK_ACQUIRE(curthread, &tcb_lock);
+		tcb = _tcb_ctor(thread, 0 /* not initial tls */);
+		THR_LOCK_RELEASE(curthread, &tcb_lock);
+	} else {
+		tcb = _tcb_ctor(thread, 1 /* initial tls */);
 	}
-	if (thread) {
+	if (tcb != NULL) {
 		memset(thread, 0, sizeof(*thread));
 		thread->tcb = tcb;
+	} else {
+		thr_destroy(curthread, thread);
+		thread = NULL;
 	}
 	return (thread);
 }
@@ -184,10 +184,26 @@ _thr_free(struct pthread *curthread, struct pthread *thread)
 		free(thread->name);
 		thread->name = NULL;
 	}
+	/*
+	 * Always free tcb, as we only know it is part of RTLD TLS
+	 * block, but don't know its detail and can not assume how
+	 * it works, so better to avoid caching it here.
+	 */
+	if (curthread != NULL) {
+		THR_LOCK_ACQUIRE(curthread, &tcb_lock);
+		_tcb_dtor(thread->tcb);
+		THR_LOCK_RELEASE(curthread, &tcb_lock);
+	} else {
+		_tcb_dtor(thread->tcb);
+	}
+	thread->tcb = NULL;
 	if ((curthread == NULL) || (free_thread_count >= MAX_CACHED_THREADS)) {
 		thr_destroy(curthread, thread);
 	} else {
-		/* Add the thread to the free thread list. */
+		/*
+		 * Add the thread to the free thread list, this also avoids
+		 * pthread id is reused too quickly, may help some buggy apps.
+		 */
 		THR_LOCK_ACQUIRE(curthread, &free_thread_lock);
 		TAILQ_INSERT_TAIL(&free_threadq, thread, tle);
 		free_thread_count++;
@@ -196,15 +212,8 @@ _thr_free(struct pthread *curthread, struct pthread *thread)
 }
 
 static void
-thr_destroy(struct pthread *curthread, struct pthread *thread)
+thr_destroy(struct pthread *curthread __unused, struct pthread *thread)
 {
-	if (curthread) {
-		THR_LOCK_ACQUIRE(curthread, &tcb_lock);
-		_tcb_dtor(thread->tcb);
-		THR_LOCK_RELEASE(curthread, &tcb_lock);
-	} else {
-		_tcb_dtor(thread->tcb);
-	}
 	free(thread);
 }
 
-- 
2.41.0