[PATCH] radix-tree: Remove unnecessary indirections and clean up code
- There is frequent use of indirections in the radix code. This patch
removes those indirections, makes the code more readable and allows
the compilers to generate better code.
- Removing indirections allows the removal of several casts.
- Removing indirections allows the reduction of the radix_tree_path
size from 3 to 2 words.
- Use pathp-> consistently.
- Remove unnecessary tmp variable in radix_tree_insert
- Separate the upper layer processing from the lowest layer in __lookup()
in order to make it easier to understand what is going on and allow
compilers to generate better code for the loop.
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: James Bottomley <James.Bottomley@steeleye.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index 10bed1c..2e9bd54 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -1,6 +1,7 @@
/*
* Copyright (C) 2001 Momchil Velikov
* Portions Copyright (C) 2001 Christoph Hellwig
+ * Copyright (C) 2005 SGI, Christoph Lameter <clameter@sgi.com>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
@@ -51,7 +52,7 @@
};
struct radix_tree_path {
- struct radix_tree_node *node, **slot;
+ struct radix_tree_node *node;
int offset;
};
@@ -227,7 +228,7 @@
int radix_tree_insert(struct radix_tree_root *root,
unsigned long index, void *item)
{
- struct radix_tree_node *node = NULL, *tmp, **slot;
+ struct radix_tree_node *node = NULL, *slot;
unsigned int height, shift;
int offset;
int error;
@@ -240,38 +241,42 @@
return error;
}
- slot = &root->rnode;
+ slot = root->rnode;
height = root->height;
shift = (height-1) * RADIX_TREE_MAP_SHIFT;
offset = 0; /* uninitialised var warning */
while (height > 0) {
- if (*slot == NULL) {
+ if (slot == NULL) {
/* Have to add a child node. */
- if (!(tmp = radix_tree_node_alloc(root)))
+ if (!(slot = radix_tree_node_alloc(root)))
return -ENOMEM;
- *slot = tmp;
- if (node)
+ if (node) {
+ node->slots[offset] = slot;
node->count++;
+ } else
+ root->rnode = slot;
}
/* Go a level down */
offset = (index >> shift) & RADIX_TREE_MAP_MASK;
- node = *slot;
- slot = (struct radix_tree_node **)(node->slots + offset);
+ node = slot;
+ slot = node->slots[offset];
shift -= RADIX_TREE_MAP_SHIFT;
height--;
}
- if (*slot != NULL)
+ if (slot != NULL)
return -EEXIST;
+
if (node) {
node->count++;
+ node->slots[offset] = item;
BUG_ON(tag_get(node, 0, offset));
BUG_ON(tag_get(node, 1, offset));
- }
+ } else
+ root->rnode = item;
- *slot = item;
return 0;
}
EXPORT_SYMBOL(radix_tree_insert);
@@ -286,27 +291,25 @@
void *radix_tree_lookup(struct radix_tree_root *root, unsigned long index)
{
unsigned int height, shift;
- struct radix_tree_node **slot;
+ struct radix_tree_node *slot;
height = root->height;
if (index > radix_tree_maxindex(height))
return NULL;
shift = (height-1) * RADIX_TREE_MAP_SHIFT;
- slot = &root->rnode;
+ slot = root->rnode;
while (height > 0) {
- if (*slot == NULL)
+ if (slot == NULL)
return NULL;
- slot = (struct radix_tree_node **)
- ((*slot)->slots +
- ((index >> shift) & RADIX_TREE_MAP_MASK));
+ slot = slot->slots[(index >> shift) & RADIX_TREE_MAP_MASK];
shift -= RADIX_TREE_MAP_SHIFT;
height--;
}
- return *slot;
+ return slot;
}
EXPORT_SYMBOL(radix_tree_lookup);
@@ -326,27 +329,27 @@
unsigned long index, int tag)
{
unsigned int height, shift;
- struct radix_tree_node **slot;
+ struct radix_tree_node *slot;
height = root->height;
if (index > radix_tree_maxindex(height))
return NULL;
shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
- slot = &root->rnode;
+ slot = root->rnode;
while (height > 0) {
int offset;
offset = (index >> shift) & RADIX_TREE_MAP_MASK;
- tag_set(*slot, tag, offset);
- slot = (struct radix_tree_node **)((*slot)->slots + offset);
- BUG_ON(*slot == NULL);
+ tag_set(slot, tag, offset);
+ slot = slot->slots[offset];
+ BUG_ON(slot == NULL);
shift -= RADIX_TREE_MAP_SHIFT;
height--;
}
- return *slot;
+ return slot;
}
EXPORT_SYMBOL(radix_tree_tag_set);
@@ -367,6 +370,7 @@
unsigned long index, int tag)
{
struct radix_tree_path path[RADIX_TREE_MAX_PATH], *pathp = path;
+ struct radix_tree_node *slot;
unsigned int height, shift;
void *ret = NULL;
@@ -376,38 +380,37 @@
shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
pathp->node = NULL;
- pathp->slot = &root->rnode;
+ slot = root->rnode;
while (height > 0) {
int offset;
- if (*pathp->slot == NULL)
+ if (slot == NULL)
goto out;
offset = (index >> shift) & RADIX_TREE_MAP_MASK;
pathp[1].offset = offset;
- pathp[1].node = *pathp[0].slot;
- pathp[1].slot = (struct radix_tree_node **)
- (pathp[1].node->slots + offset);
+ pathp[1].node = slot;
+ slot = slot->slots[offset];
pathp++;
shift -= RADIX_TREE_MAP_SHIFT;
height--;
}
- ret = *pathp[0].slot;
+ ret = slot;
if (ret == NULL)
goto out;
do {
int idx;
- tag_clear(pathp[0].node, tag, pathp[0].offset);
+ tag_clear(pathp->node, tag, pathp->offset);
for (idx = 0; idx < RADIX_TREE_TAG_LONGS; idx++) {
- if (pathp[0].node->tags[tag][idx])
+ if (pathp->node->tags[tag][idx])
goto out;
}
pathp--;
- } while (pathp[0].node);
+ } while (pathp->node);
out:
return ret;
}
@@ -429,7 +432,7 @@
unsigned long index, int tag)
{
unsigned int height, shift;
- struct radix_tree_node **slot;
+ struct radix_tree_node *slot;
int saw_unset_tag = 0;
height = root->height;
@@ -437,12 +440,12 @@
return 0;
shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
- slot = &root->rnode;
+ slot = root->rnode;
for ( ; ; ) {
int offset;
- if (*slot == NULL)
+ if (slot == NULL)
return 0;
offset = (index >> shift) & RADIX_TREE_MAP_MASK;
@@ -451,15 +454,15 @@
* This is just a debug check. Later, we can bale as soon as
* we see an unset tag.
*/
- if (!tag_get(*slot, tag, offset))
+ if (!tag_get(slot, tag, offset))
saw_unset_tag = 1;
if (height == 1) {
- int ret = tag_get(*slot, tag, offset);
+ int ret = tag_get(slot, tag, offset);
BUG_ON(ret && saw_unset_tag);
return ret;
}
- slot = (struct radix_tree_node **)((*slot)->slots + offset);
+ slot = slot->slots[offset];
shift -= RADIX_TREE_MAP_SHIFT;
height--;
}
@@ -472,17 +475,21 @@
unsigned int max_items, unsigned long *next_index)
{
unsigned int nr_found = 0;
- unsigned int shift;
- unsigned int height = root->height;
+ unsigned int shift, height;
struct radix_tree_node *slot;
+ unsigned long i;
+
+ height = root->height;
+ if (height == 0)
+ goto out;
shift = (height-1) * RADIX_TREE_MAP_SHIFT;
slot = root->rnode;
- while (height > 0) {
- unsigned long i = (index >> shift) & RADIX_TREE_MAP_MASK;
+ for ( ; height > 1; height--) {
- for ( ; i < RADIX_TREE_MAP_SIZE; i++) {
+ for (i = (index >> shift) & RADIX_TREE_MAP_MASK ;
+ i < RADIX_TREE_MAP_SIZE; i++) {
if (slot->slots[i] != NULL)
break;
index &= ~((1UL << shift) - 1);
@@ -492,22 +499,20 @@
}
if (i == RADIX_TREE_MAP_SIZE)
goto out;
- height--;
- if (height == 0) { /* Bottom level: grab some items */
- unsigned long j = index & RADIX_TREE_MAP_MASK;
- for ( ; j < RADIX_TREE_MAP_SIZE; j++) {
- index++;
- if (slot->slots[j]) {
- results[nr_found++] = slot->slots[j];
- if (nr_found == max_items)
- goto out;
- }
- }
- }
shift -= RADIX_TREE_MAP_SHIFT;
slot = slot->slots[i];
}
+
+ /* Bottom level: grab some items */
+ for (i = index & RADIX_TREE_MAP_MASK; i < RADIX_TREE_MAP_SIZE; i++) {
+ index++;
+ if (slot->slots[i]) {
+ results[nr_found++] = slot->slots[i];
+ if (nr_found == max_items)
+ goto out;
+ }
+ }
out:
*next_index = index;
return nr_found;
@@ -655,6 +660,7 @@
{
struct radix_tree_path path[RADIX_TREE_MAX_PATH], *pathp = path;
struct radix_tree_path *orig_pathp;
+ struct radix_tree_node *slot;
unsigned int height, shift;
void *ret = NULL;
char tags[RADIX_TREE_TAGS];
@@ -666,25 +672,23 @@
shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
pathp->node = NULL;
- pathp->slot = &root->rnode;
+ slot = root->rnode;
- while (height > 0) {
+ for ( ; height > 0; height--) {
int offset;
- if (*pathp->slot == NULL)
+ if (slot == NULL)
goto out;
offset = (index >> shift) & RADIX_TREE_MAP_MASK;
pathp[1].offset = offset;
- pathp[1].node = *pathp[0].slot;
- pathp[1].slot = (struct radix_tree_node **)
- (pathp[1].node->slots + offset);
+ pathp[1].node = slot;
+ slot = slot->slots[offset];
pathp++;
shift -= RADIX_TREE_MAP_SHIFT;
- height--;
}
- ret = *pathp[0].slot;
+ ret = slot;
if (ret == NULL)
goto out;
@@ -704,10 +708,10 @@
if (tags[tag])
continue;
- tag_clear(pathp[0].node, tag, pathp[0].offset);
+ tag_clear(pathp->node, tag, pathp->offset);
for (idx = 0; idx < RADIX_TREE_TAG_LONGS; idx++) {
- if (pathp[0].node->tags[tag][idx]) {
+ if (pathp->node->tags[tag][idx]) {
tags[tag] = 1;
nr_cleared_tags--;
break;
@@ -715,18 +719,19 @@
}
}
pathp--;
- } while (pathp[0].node && nr_cleared_tags);
+ } while (pathp->node && nr_cleared_tags);
- pathp = orig_pathp;
- *pathp[0].slot = NULL;
- while (pathp[0].node && --pathp[0].node->count == 0) {
- pathp--;
- BUG_ON(*pathp[0].slot == NULL);
- *pathp[0].slot = NULL;
- radix_tree_node_free(pathp[1].node);
+ /* Now free the nodes we do not need anymore */
+ for (pathp = orig_pathp; pathp->node; pathp--) {
+ pathp->node->slots[pathp->offset] = NULL;
+ if (--pathp->node->count)
+ goto out;
+
+ /* Node with zero slots in use so free it */
+ radix_tree_node_free(pathp->node);
}
- if (root->rnode == NULL)
- root->height = 0;
+ root->rnode = NULL;
+ root->height = 0;
out:
return ret;
}