6091 avl_add doesn't assert on non-debug builds
Reviewed by: Andy Stormont <astormont@racktopsystems.com>

@@ -23,10 +23,11 @@
  * Use is subject to license terms.
  */
 
 /*
  * Copyright (c) 2014 by Delphix. All rights reserved.
+ * Copyright 2015 Nexenta Systems, Inc.  All rights reserved.
  */
 
 /*
  * AVL - generic AVL tree implementation for kernel use
  *

@@ -633,18 +634,21 @@
         avl_index_t where;
 
         /*
          * This is unfortunate.  We want to call panic() here, even for
          * non-DEBUG kernels.  In userland, however, we can't depend on anything
-         * in libc or else the rtld build process gets confused.  So, all we can
-         * do in userland is resort to a normal ASSERT().
+         * in libc or else the rtld build process gets confused.
+         * Thankfully, rtld provides us with its own assfail() so we can use
+         * that here.  We use assfail() directly to get a nice error message
+         * in the core - much like what panic() does for crashdumps.
          */
         if (avl_find(tree, new_node, &where) != NULL)
 #ifdef _KERNEL
                 panic("avl_find() succeeded inside avl_add()");
 #else
-                ASSERT(0);
+                (void) assfail("avl_find() succeeded inside avl_add()",
+                    __FILE__, __LINE__);
 #endif
         avl_insert(tree, new_node, where);
 }
 
 /*