Correct two libmemstat(3) bugs:

- Move memory_type_list flushing logic from memstat_mtl_free() to
  _memstat_mtl_empty(), a libmemstat-internal function that can
  be called from other parts of the library.  Invoke
  _memstat_mtl_empty() from memstat_mtl_free(), which also frees
  the containing list structure.

  Invoke _memstat_mtl_empty() instead of memstat_mtl_free() in
  various error cases in memstat_malloc.c and memstat_uma.c, which
  previously resulted in the list being freed prematurely.

- Reverse the order of updating the mt_kegfree and mt_free fields
  of the memory_type in memstat_uma.c, otherwise keg free items
  won't be counted properly for non-secondary zones.

MFC after:	3 days

lib/libmemstat/memstat.c

@@ -88,7 +88,7 @@ memstat_mtl_next(struct memory_type *mtp)
 }
 
 void
-memstat_mtl_free(struct memory_type_list *list)
+_memstat_mtl_empty(struct memory_type_list *list)
 {
 	struct memory_type *mtp;
 
@@ -96,6 +96,13 @@ memstat_mtl_free(struct memory_type_list *list)
 		LIST_REMOVE(mtp, mt_list);
 		free(mtp);
 	}
+}
+
+void
+memstat_mtl_free(struct memory_type_list *list)
+{
+
+	_memstat_mtl_empty(list);
 	free(list);
 }
 

lib/libmemstat/memstat_internal.h

@@ -116,6 +116,7 @@ struct memory_type_list {
 	int				mtl_error;
 };
 
+void			 _memstat_mtl_empty(struct memory_type_list *list);
 struct memory_type	*_memstat_mt_allocate(struct memory_type_list *list,
 			    int allocator, const char *name);
 void			 _memstat_mt_reset_stats(struct memory_type *mtp);

lib/libmemstat/memstat_malloc.c

@@ -175,7 +175,7 @@ memstat_sysctl_malloc(struct memory_type_list *list, int flags)
 			mtp = _memstat_mt_allocate(list, ALLOCATOR_MALLOC,
 			    mthp->mth_name);
 		if (mtp == NULL) {
-			memstat_mtl_free(list);
+			_memstat_mtl_empty(list);
 			free(buffer);
 			list->mtl_error = MEMSTAT_ERROR_NOMEMORY;
 			return (-1);

lib/libmemstat/memstat_uma.c

@@ -176,7 +176,7 @@ memstat_sysctl_uma(struct memory_type_list *list, int flags)
 			mtp = _memstat_mt_allocate(list, ALLOCATOR_UMA,
 			    uthp->uth_name);
 		if (mtp == NULL) {
-			memstat_mtl_free(list);
+			_memstat_mtl_empty(list);
 			free(buffer);
 			list->mtl_error = MEMSTAT_ERROR_NOMEMORY;
 			return (-1);
@@ -218,8 +218,8 @@ memstat_sysctl_uma(struct memory_type_list *list, int flags)
 		 * items only in the primary zone.
 		 */
 		if (!(uthp->uth_zone_flags & UTH_ZONE_SECONDARY)) {
-			mtp->mt_free += mtp->mt_kegfree;
 			mtp->mt_kegfree = uthp->uth_keg_free;
+			mtp->mt_free += mtp->mt_kegfree;
 		}
 		mtp->mt_free += mtp->mt_zonefree;
 	}