From 23f766944414893832e8a3d10afbceded194916f Mon Sep 17 00:00:00 2001
From: mtm <mtm@FreeBSD.org>
Date: Mon, 26 May 2003 00:37:07 +0000
Subject: [PATCH] Decouple the thread stack [de]allocating functions from the
 'dead threads list' lock. It's not really necessary and we don't need the
 added complexity or potential for deadlocks.

Approved by:	re/blanket libthr
---
 lib/libthr/thread/thr_create.c  | 5 ++---
 lib/libthr/thread/thr_gc.c      | 2 ++
 lib/libthr/thread/thr_private.h | 8 ++++++++
 lib/libthr/thread/thr_stack.c   | 8 ++++----
 4 files changed, 16 insertions(+), 7 deletions(-)

diff --git a/lib/libthr/thread/thr_create.c b/lib/libthr/thread/thr_create.c
index 5b0158dedad4..c86f2446a530 100644
--- a/lib/libthr/thread/thr_create.c
+++ b/lib/libthr/thread/thr_create.c
@@ -119,11 +119,10 @@ _pthread_create(pthread_t * thread, const pthread_attr_t * attr,
 	new_thread->arch_id = _set_curthread(&new_thread->ctx, new_thread, &ret);
 	if (ret != 0) {
 		if (pattr->stackaddr_attr == NULL) {
-			/* XXX - We really need to decouple from this lock */
-			DEAD_LIST_LOCK;
+			STACK_LOCK;
 			_thread_stack_free(new_thread->stack,
 			    pattr->stacksize_attr, pattr->guardsize_attr);
-			DEAD_LIST_UNLOCK;
+			STACK_UNLOCK;
 		}
 		free(new_thread);
 		return (ret);
diff --git a/lib/libthr/thread/thr_gc.c b/lib/libthr/thread/thr_gc.c
index d491bffdeca5..9e263145ab5c 100644
--- a/lib/libthr/thread/thr_gc.c
+++ b/lib/libthr/thread/thr_gc.c
@@ -113,6 +113,7 @@ _thread_gc(pthread_addr_t arg)
 			 * the caller to pthread_create() and has not
 			 * been destroyed yet: 
 			 */
+			STACK_LOCK;
 			if (pthread->attr.stackaddr_attr == NULL &&
 			    pthread->stack != NULL) {
 				_thread_stack_free(pthread->stack,
@@ -120,6 +121,7 @@ _thread_gc(pthread_addr_t arg)
 				    pthread->attr.guardsize_attr);
 				pthread->stack = NULL;
 			}
+			STACK_UNLOCK;
 
 			/*
 			 * If the thread has not been detached, leave
diff --git a/lib/libthr/thread/thr_private.h b/lib/libthr/thread/thr_private.h
index d8e37b4c6093..7bf1b143b254 100644
--- a/lib/libthr/thread/thr_private.h
+++ b/lib/libthr/thread/thr_private.h
@@ -578,6 +578,14 @@ SCLASS void *_usrstack
 ;
 #endif
 
+SCLASS spinlock_t stack_lock
+#ifdef GLOBAL_PTHREAD_PRIVATE
+= _SPINLOCK_INITIALIZER
+#endif
+;
+#define STACK_LOCK	_SPINLOCK(&stack_lock);
+#define STACK_UNLOCK	_SPINUNLOCK(&stack_lock);
+
 /* List of all threads: */
 SCLASS TAILQ_HEAD(, pthread)	_thread_list
 #ifdef GLOBAL_PTHREAD_PRIVATE
diff --git a/lib/libthr/thread/thr_stack.c b/lib/libthr/thread/thr_stack.c
index 28b396bc90f4..b4063ad564ff 100644
--- a/lib/libthr/thread/thr_stack.c
+++ b/lib/libthr/thread/thr_stack.c
@@ -144,7 +144,7 @@ _thread_stack_alloc(size_t stacksize, size_t guardsize)
 		 * Use the garbage collector mutex for synchronization of the
 		 * spare stack list.
 		 */
-		DEAD_LIST_LOCK;
+		STACK_LOCK;
 
 		if ((spare_stack = LIST_FIRST(&_dstackq)) != NULL) {
 				/* Use the spare stack. */
@@ -153,7 +153,7 @@ _thread_stack_alloc(size_t stacksize, size_t guardsize)
 		}
 
 		/* Unlock the garbage collector mutex. */
-		DEAD_LIST_UNLOCK;
+		STACK_UNLOCK;
 	}
 	/*
 	 * The user specified a non-default stack and/or guard size, so try to
@@ -165,7 +165,7 @@ _thread_stack_alloc(size_t stacksize, size_t guardsize)
 		 * Use the garbage collector mutex for synchronization of the
 		 * spare stack list.
 		 */
-		DEAD_LIST_LOCK;
+		STACK_LOCK;
 
 		LIST_FOREACH(spare_stack, &_mstackq, qe) {
 			if (spare_stack->stacksize == stack_size &&
@@ -177,7 +177,7 @@ _thread_stack_alloc(size_t stacksize, size_t guardsize)
 		}
 
 		/* Unlock the garbage collector mutex. */
-		DEAD_LIST_UNLOCK;
+		STACK_UNLOCK;
 	}
 
 	/* Check if a stack was not allocated from a stack cache: */