thread_find(): now use TID lookup most of the time, which should be s…

…afer.

We reserve the location of the thread based on its stack pointer to stack
pointer validation routines.

src/lib/thread.c

@@ -679,7 +679,7 @@ thread_qid_lookup(void)
 /**
  * Find existing thread based on the supplied stack pointer.
  *
- * @param sp		a pointer to the stack
+ * @param sp		a pointer to the stack (NULL to use TIDs to locate thread)
  *
  * @return the likely thread element to which the stack pointer could relate,
  * NULL if we cannot determine the thread.
@@ -710,17 +710,19 @@ thread_find(const void *sp)
 	 * it is necessary to return the proper thread so that any lock acquired
 	 * during the critical section be properly attributed to the new thread,
 	 * or to none if we can't find the thread.
+	 *
+	 * We therefore mostly lookup threads by TID, the only time when we're
+	 * not is when we have a stack pointer and we wish to determine to which
+	 * thread it belongs.
 	 */
 
 	te = NULL;
 
-	if G_UNLIKELY(spinlock_is_held(&thread_insert_slk)) {
+	if G_LIKELY(NULL == sp) {
 		thread_t t = thread_self();
 
 		/*
-		 * We're in the middle of a new thread creation, hence it is wrong
-		 * to look for stacks since the new thread may not have its stack
-		 * setup yet.  We have to compare TIDs.
+		 * We have to compare TIDs.
 		 */
 
 		for (i = 0; i < thread_next_stid; i++) {
@@ -734,8 +736,8 @@ thread_find(const void *sp)
 	} else {
 		/*
 		 * Perform linear lookup, looking for the thread for which the stack
-		 * pointer is "above" the parameter and for which the distance to the
-		 * base of the stack is the smallest.
+		 * pointer is "above" the base of the stack and for which the distance
+		 * to that base is the smallest.
 		 */
 
 		for (i = 0; i < thread_next_stid; i++) {
@@ -748,7 +750,7 @@ thread_find(const void *sp)
 				size_t offset;
 
 				/*
-				 * Pointer is "above" the stack base, track the thread whith
+				 * Pointer is "above" the stack base, track the thread with
 				 * the smallest offset relative to the stack base.
 				 */
 
@@ -914,7 +916,7 @@ thread_suspend_others(void)
 	 * these locks).
 	 */
 
-	te = thread_find(&te);		/* Ourselves */
+	te = thread_find(NULL);		/* Ourselves */
 	if (NULL == te)
 		return 0;
 
@@ -973,7 +975,7 @@ thread_unsuspend_others(void)
 	size_t i, n = 0;
 	struct thread_element *te;
 
-	te = thread_find(&te);		/* Ourselves */
+	te = thread_find(NULL);		/* Ourselves */
 	if (NULL == te)
 		return 0;
 
@@ -1129,7 +1131,7 @@ thread_is_stack_pointer(const void *p, const void *top, unsigned *stid)
 		return FALSE;
 
 	if (NULL == top) {
-		if (thread_get_element() != te)
+		if (thread_self() != te->tid)
 			return FALSE;		/* Not in the current thread */
 		top = &te;
 	}
@@ -1260,7 +1262,7 @@ thread_pending_add(int increment)
 {
 	struct thread_element *te;
 
-	te = thread_find(&te);
+	te = thread_find(NULL);
 	if G_UNLIKELY(NULL == te)
 		return;
 
@@ -1397,7 +1399,7 @@ thread_lock_current_dump(void)
 {
 	struct thread_element *te;
 
-	te = thread_find(&te);
+	te = thread_find(NULL);
 	if G_UNLIKELY(NULL == te)
 		return;
 
@@ -1421,7 +1423,7 @@ thread_lock_got(const void *lock, enum thread_lock_kind kind)
 	 * thread element is already in the process of being created.
 	 */
 
-	te = thread_find(&te);
+	te = thread_find(NULL);
 	if G_UNLIKELY(NULL == te)
 		return;
 
@@ -1458,7 +1460,7 @@ thread_lock_released(const void *lock, enum thread_lock_kind kind)
 	 * thread element at lock time but are able to get one now.
 	 */
 
-	te = thread_find(&te);
+	te = thread_find(NULL);
 	if G_UNLIKELY(NULL == te)
 		return;
 
@@ -1532,7 +1534,7 @@ thread_lock_holds(const volatile void *lock)
 	 * thread element at lock time but are able to get one now.
 	 */
 
-	te = thread_find(&te);
+	te = thread_find(NULL);
 	if G_UNLIKELY(NULL == te)
 		return FALSE;
 
@@ -1559,7 +1561,7 @@ thread_lock_count(void)
 {
 	struct thread_element *te;
 
-	te = thread_find(&te);
+	te = thread_find(NULL);
 	if G_UNLIKELY(NULL == te)
 		return 0;
 
@@ -1624,7 +1626,7 @@ thread_lock_deadlock(const volatile void *lock)
 	deadlocked = TRUE;
 	atomic_mb();
 
-	te = thread_find(&te);
+	te = thread_find(NULL);
 	if G_UNLIKELY(NULL == te) {
 		s_miniinfo("no thread to list owned locks");
 		return;