From 201b6264ff3865090747f58f48e087c3a35e0dbc Mon Sep 17 00:00:00 2001 From: Christoph Lameter Date: Tue, 6 Sep 2005 15:16:46 -0700 Subject: [PATCH] [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 Cc: Nick Piggin Cc: James Bottomley Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- lib/radix-tree.c | 159 ++++++++++++++++++++++++----------------------- 1 file changed, 82 insertions(+), 77 deletions(-) diff --git a/lib/radix-tree.c b/lib/radix-tree.c index 10bed1c8c3..2e9bd54beb 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 * * 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_node { }; struct radix_tree_path { - struct radix_tree_node *node, **slot; + struct radix_tree_node *node; int offset; }; @@ -227,7 +228,7 @@ out: 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 @@ int radix_tree_insert(struct radix_tree_root *root, 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 @@ EXPORT_SYMBOL(radix_tree_insert); 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 @@ void *radix_tree_tag_set(struct radix_tree_root *root, 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 @@ void *radix_tree_tag_clear(struct radix_tree_root *root, 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 @@ void *radix_tree_tag_clear(struct radix_tree_root *root, 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 @@ int radix_tree_tag_get(struct radix_tree_root *root, 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 @@ int radix_tree_tag_get(struct radix_tree_root *root, 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 @@ int radix_tree_tag_get(struct radix_tree_root *root, * 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 @@ __lookup(struct radix_tree_root *root, void **results, unsigned long index, 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 @@ __lookup(struct radix_tree_root *root, void **results, unsigned long index, } 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 @@ void *radix_tree_delete(struct radix_tree_root *root, unsigned long index) { 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 @@ void *radix_tree_delete(struct radix_tree_root *root, unsigned long index) 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 @@ void *radix_tree_delete(struct radix_tree_root *root, unsigned long index) 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 @@ void *radix_tree_delete(struct radix_tree_root *root, unsigned long index) } } 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; } -- 2.39.5