svn commit: r248684 - head/sys/vm

[Alan Cox]

Author: alc
Date: Sun Mar 24 16:43:07 2013
New Revision: 248684
URL: http://svnweb.freebsd.org/changeset/base/248684

Log:
  Micro-optimize the control flow in a few places.  Eliminate a panic call
  that could never be reached in vm_radix_insert().  (If the pointer being
  checked by the panic call were ever NULL, the immmediately preceding loop
  would have already crashed on a NULL pointer dereference.)
  
  Reviewed by:	attilio (an earlier version)
  Sponsored by:	EMC / Isilon Storage Division

Modified:
  head/sys/vm/vm_radix.c

Modified: head/sys/vm/vm_radix.c
==============================================================================
--- head/sys/vm/vm_radix.c	Sun Mar 24 16:41:23 2013	(r248683)
+++ head/sys/vm/vm_radix.c	Sun Mar 24 16:43:07 2013	(r248684)
@@ -310,7 +310,9 @@ vm_radix_reclaim_allnodes_int(struct vm_
 {
 	int slot;
 
-	for (slot = 0; slot < VM_RADIX_COUNT && rnode->rn_count != 0; slot++) {
+	KASSERT(rnode->rn_count <= VM_RADIX_COUNT,
+	    ("vm_radix_reclaim_allnodes_int: bad count in rnode %p", rnode));
+	for (slot = 0; rnode->rn_count != 0; slot++) {
 		if (rnode->rn_child[slot] == NULL)
 			continue;
 		if (vm_radix_node_page(rnode->rn_child[slot]) == NULL)
@@ -414,9 +416,7 @@ vm_radix_insert(struct vm_radix *rtree, 
 		vm_radix_addpage(rnode, index, 0, page);
 		return;
 	}
-	while (rnode != NULL) {
-		if (vm_radix_keybarr(rnode, index))
-			break;
+	do {
 		slot = vm_radix_slot(index, rnode->rn_clev);
 		m = vm_radix_node_page(rnode->rn_child[slot]);
 		if (m != NULL) {
@@ -437,9 +437,7 @@ vm_radix_insert(struct vm_radix *rtree, 
 			return;
 		}
 		rnode = rnode->rn_child[slot];
-	}
-	if (rnode == NULL)
-		panic("%s: path traversal ended unexpectedly", __func__);
+	} while (!vm_radix_keybarr(rnode, index));
 
 	/*
 	 * Scan the trie from the top and find the parent to insert
@@ -748,8 +746,8 @@ vm_radix_reclaim_allnodes(struct vm_radi
 	root = vm_radix_getroot(rtree);
 	if (root == NULL)
 		return;
-	vm_radix_reclaim_allnodes_int(root);
 	vm_radix_setroot(rtree, NULL);
+	vm_radix_reclaim_allnodes_int(root);
 }
 
 #ifdef DDB