[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>
This commit is contained in:
Christoph Lameter
Linus Torvalds
Родитель
987132bb0b
Коммит
201b6264ff
159
lib/radix-tree.c
159
lib/radix-tree.c
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@ -1,6 +1,7 @@
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/*
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* Copyright (C) 2001 Momchil Velikov
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* Portions Copyright (C) 2001 Christoph Hellwig
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* Copyright (C) 2005 SGI, Christoph Lameter <clameter@sgi.com>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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@ -51,7 +52,7 @@ struct radix_tree_node {
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};
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struct radix_tree_path {
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struct radix_tree_node *node, **slot;
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struct radix_tree_node *node;
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int offset;
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};
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@ -227,7 +228,7 @@ out:
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int radix_tree_insert(struct radix_tree_root *root,
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unsigned long index, void *item)
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{
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struct radix_tree_node *node = NULL, *tmp, **slot;
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struct radix_tree_node *node = NULL, *slot;
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unsigned int height, shift;
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int offset;
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int error;
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@ -240,38 +241,42 @@ int radix_tree_insert(struct radix_tree_root *root,
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return error;
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}
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slot = &root->rnode;
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slot = root->rnode;
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height = root->height;
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shift = (height-1) * RADIX_TREE_MAP_SHIFT;
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offset = 0; /* uninitialised var warning */
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while (height > 0) {
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if (*slot == NULL) {
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if (slot == NULL) {
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/* Have to add a child node. */
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if (!(tmp = radix_tree_node_alloc(root)))
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if (!(slot = radix_tree_node_alloc(root)))
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return -ENOMEM;
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*slot = tmp;
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if (node)
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if (node) {
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node->slots[offset] = slot;
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node->count++;
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} else
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root->rnode = slot;
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}
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/* Go a level down */
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offset = (index >> shift) & RADIX_TREE_MAP_MASK;
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node = *slot;
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slot = (struct radix_tree_node **)(node->slots + offset);
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node = slot;
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slot = node->slots[offset];
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shift -= RADIX_TREE_MAP_SHIFT;
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height--;
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}
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if (*slot != NULL)
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if (slot != NULL)
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return -EEXIST;
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if (node) {
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node->count++;
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node->slots[offset] = item;
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BUG_ON(tag_get(node, 0, offset));
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BUG_ON(tag_get(node, 1, offset));
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}
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} else
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root->rnode = item;
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*slot = item;
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return 0;
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}
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EXPORT_SYMBOL(radix_tree_insert);
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@ -286,27 +291,25 @@ EXPORT_SYMBOL(radix_tree_insert);
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void *radix_tree_lookup(struct radix_tree_root *root, unsigned long index)
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{
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unsigned int height, shift;
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struct radix_tree_node **slot;
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struct radix_tree_node *slot;
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height = root->height;
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if (index > radix_tree_maxindex(height))
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return NULL;
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shift = (height-1) * RADIX_TREE_MAP_SHIFT;
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slot = &root->rnode;
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slot = root->rnode;
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while (height > 0) {
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if (*slot == NULL)
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if (slot == NULL)
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return NULL;
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slot = (struct radix_tree_node **)
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((*slot)->slots +
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((index >> shift) & RADIX_TREE_MAP_MASK));
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slot = slot->slots[(index >> shift) & RADIX_TREE_MAP_MASK];
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shift -= RADIX_TREE_MAP_SHIFT;
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height--;
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}
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return *slot;
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return slot;
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}
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EXPORT_SYMBOL(radix_tree_lookup);
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@ -326,27 +329,27 @@ void *radix_tree_tag_set(struct radix_tree_root *root,
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unsigned long index, int tag)
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{
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unsigned int height, shift;
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struct radix_tree_node **slot;
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struct radix_tree_node *slot;
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height = root->height;
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if (index > radix_tree_maxindex(height))
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return NULL;
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shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
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slot = &root->rnode;
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slot = root->rnode;
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while (height > 0) {
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int offset;
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offset = (index >> shift) & RADIX_TREE_MAP_MASK;
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tag_set(*slot, tag, offset);
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slot = (struct radix_tree_node **)((*slot)->slots + offset);
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BUG_ON(*slot == NULL);
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tag_set(slot, tag, offset);
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slot = slot->slots[offset];
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BUG_ON(slot == NULL);
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shift -= RADIX_TREE_MAP_SHIFT;
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height--;
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}
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return *slot;
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return slot;
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}
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EXPORT_SYMBOL(radix_tree_tag_set);
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@ -367,6 +370,7 @@ void *radix_tree_tag_clear(struct radix_tree_root *root,
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unsigned long index, int tag)
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{
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struct radix_tree_path path[RADIX_TREE_MAX_PATH], *pathp = path;
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struct radix_tree_node *slot;
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unsigned int height, shift;
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void *ret = NULL;
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@ -376,38 +380,37 @@ void *radix_tree_tag_clear(struct radix_tree_root *root,
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shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
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pathp->node = NULL;
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pathp->slot = &root->rnode;
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slot = root->rnode;
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while (height > 0) {
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int offset;
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if (*pathp->slot == NULL)
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if (slot == NULL)
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goto out;
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offset = (index >> shift) & RADIX_TREE_MAP_MASK;
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pathp[1].offset = offset;
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pathp[1].node = *pathp[0].slot;
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pathp[1].slot = (struct radix_tree_node **)
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(pathp[1].node->slots + offset);
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pathp[1].node = slot;
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slot = slot->slots[offset];
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pathp++;
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shift -= RADIX_TREE_MAP_SHIFT;
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height--;
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}
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ret = *pathp[0].slot;
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ret = slot;
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if (ret == NULL)
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goto out;
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do {
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int idx;
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tag_clear(pathp[0].node, tag, pathp[0].offset);
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tag_clear(pathp->node, tag, pathp->offset);
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for (idx = 0; idx < RADIX_TREE_TAG_LONGS; idx++) {
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if (pathp[0].node->tags[tag][idx])
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if (pathp->node->tags[tag][idx])
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goto out;
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}
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pathp--;
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} while (pathp[0].node);
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} while (pathp->node);
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out:
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return ret;
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}
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@ -429,7 +432,7 @@ int radix_tree_tag_get(struct radix_tree_root *root,
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unsigned long index, int tag)
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{
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unsigned int height, shift;
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struct radix_tree_node **slot;
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struct radix_tree_node *slot;
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int saw_unset_tag = 0;
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height = root->height;
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@ -437,12 +440,12 @@ int radix_tree_tag_get(struct radix_tree_root *root,
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return 0;
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shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
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slot = &root->rnode;
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slot = root->rnode;
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for ( ; ; ) {
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int offset;
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if (*slot == NULL)
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if (slot == NULL)
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return 0;
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offset = (index >> shift) & RADIX_TREE_MAP_MASK;
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@ -451,15 +454,15 @@ int radix_tree_tag_get(struct radix_tree_root *root,
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* This is just a debug check. Later, we can bale as soon as
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* we see an unset tag.
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*/
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if (!tag_get(*slot, tag, offset))
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if (!tag_get(slot, tag, offset))
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saw_unset_tag = 1;
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if (height == 1) {
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int ret = tag_get(*slot, tag, offset);
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int ret = tag_get(slot, tag, offset);
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BUG_ON(ret && saw_unset_tag);
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return ret;
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}
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slot = (struct radix_tree_node **)((*slot)->slots + offset);
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slot = slot->slots[offset];
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shift -= RADIX_TREE_MAP_SHIFT;
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height--;
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}
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@ -472,17 +475,21 @@ __lookup(struct radix_tree_root *root, void **results, unsigned long index,
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unsigned int max_items, unsigned long *next_index)
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{
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unsigned int nr_found = 0;
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unsigned int shift;
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unsigned int height = root->height;
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unsigned int shift, height;
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struct radix_tree_node *slot;
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unsigned long i;
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height = root->height;
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if (height == 0)
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goto out;
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shift = (height-1) * RADIX_TREE_MAP_SHIFT;
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slot = root->rnode;
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while (height > 0) {
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unsigned long i = (index >> shift) & RADIX_TREE_MAP_MASK;
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for ( ; height > 1; height--) {
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for ( ; i < RADIX_TREE_MAP_SIZE; i++) {
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for (i = (index >> shift) & RADIX_TREE_MAP_MASK ;
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i < RADIX_TREE_MAP_SIZE; i++) {
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if (slot->slots[i] != NULL)
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break;
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index &= ~((1UL << shift) - 1);
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@ -492,22 +499,20 @@ __lookup(struct radix_tree_root *root, void **results, unsigned long index,
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}
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if (i == RADIX_TREE_MAP_SIZE)
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goto out;
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height--;
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if (height == 0) { /* Bottom level: grab some items */
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unsigned long j = index & RADIX_TREE_MAP_MASK;
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for ( ; j < RADIX_TREE_MAP_SIZE; j++) {
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index++;
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if (slot->slots[j]) {
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results[nr_found++] = slot->slots[j];
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if (nr_found == max_items)
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goto out;
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}
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}
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}
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shift -= RADIX_TREE_MAP_SHIFT;
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slot = slot->slots[i];
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}
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/* Bottom level: grab some items */
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for (i = index & RADIX_TREE_MAP_MASK; i < RADIX_TREE_MAP_SIZE; i++) {
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index++;
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if (slot->slots[i]) {
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results[nr_found++] = slot->slots[i];
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if (nr_found == max_items)
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goto out;
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}
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}
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out:
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*next_index = index;
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return nr_found;
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@ -655,6 +660,7 @@ void *radix_tree_delete(struct radix_tree_root *root, unsigned long index)
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{
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struct radix_tree_path path[RADIX_TREE_MAX_PATH], *pathp = path;
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struct radix_tree_path *orig_pathp;
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struct radix_tree_node *slot;
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unsigned int height, shift;
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void *ret = NULL;
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char tags[RADIX_TREE_TAGS];
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@ -666,25 +672,23 @@ void *radix_tree_delete(struct radix_tree_root *root, unsigned long index)
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shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
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pathp->node = NULL;
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pathp->slot = &root->rnode;
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slot = root->rnode;
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while (height > 0) {
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for ( ; height > 0; height--) {
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int offset;
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if (*pathp->slot == NULL)
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if (slot == NULL)
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goto out;
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offset = (index >> shift) & RADIX_TREE_MAP_MASK;
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pathp[1].offset = offset;
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pathp[1].node = *pathp[0].slot;
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pathp[1].slot = (struct radix_tree_node **)
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(pathp[1].node->slots + offset);
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pathp[1].node = slot;
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slot = slot->slots[offset];
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pathp++;
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shift -= RADIX_TREE_MAP_SHIFT;
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height--;
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}
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ret = *pathp[0].slot;
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ret = slot;
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if (ret == NULL)
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goto out;
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@ -704,10 +708,10 @@ void *radix_tree_delete(struct radix_tree_root *root, unsigned long index)
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if (tags[tag])
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continue;
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tag_clear(pathp[0].node, tag, pathp[0].offset);
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tag_clear(pathp->node, tag, pathp->offset);
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for (idx = 0; idx < RADIX_TREE_TAG_LONGS; idx++) {
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if (pathp[0].node->tags[tag][idx]) {
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if (pathp->node->tags[tag][idx]) {
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tags[tag] = 1;
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nr_cleared_tags--;
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break;
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@ -715,18 +719,19 @@ void *radix_tree_delete(struct radix_tree_root *root, unsigned long index)
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}
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}
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pathp--;
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} while (pathp[0].node && nr_cleared_tags);
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} while (pathp->node && nr_cleared_tags);
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pathp = orig_pathp;
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*pathp[0].slot = NULL;
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while (pathp[0].node && --pathp[0].node->count == 0) {
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pathp--;
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BUG_ON(*pathp[0].slot == NULL);
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*pathp[0].slot = NULL;
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radix_tree_node_free(pathp[1].node);
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/* Now free the nodes we do not need anymore */
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for (pathp = orig_pathp; pathp->node; pathp--) {
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pathp->node->slots[pathp->offset] = NULL;
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if (--pathp->node->count)
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goto out;
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/* Node with zero slots in use so free it */
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radix_tree_node_free(pathp->node);
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}
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if (root->rnode == NULL)
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root->height = 0;
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root->rnode = NULL;
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root->height = 0;
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out:
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return ret;
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}
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