/*
* Copyright (C) 2001 Momchil Velikov
* Portions Copyright (C) 2001 Christoph Hellwig
- * Copyright (C) 2005 SGI, Christoph Lameter <clameter@sgi.com>
+ * Copyright (C) 2005 SGI, Christoph Lameter
+ * Copyright (C) 2006 Nick Piggin
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
#include <linux/gfp.h>
#include <linux/string.h>
#include <linux/bitops.h>
+#include <linux/rcupdate.h>
#ifdef __KERNEL__
-#define RADIX_TREE_MAP_SHIFT 6
+#define RADIX_TREE_MAP_SHIFT (CONFIG_BASE_SMALL ? 4 : 6)
#else
#define RADIX_TREE_MAP_SHIFT 3 /* For more stressful testing */
#endif
((RADIX_TREE_MAP_SIZE + BITS_PER_LONG - 1) / BITS_PER_LONG)
struct radix_tree_node {
+ unsigned int height; /* Height from the bottom */
unsigned int count;
+ struct rcu_head rcu_head;
void *slots[RADIX_TREE_MAP_SIZE];
unsigned long tags[RADIX_TREE_MAX_TAGS][RADIX_TREE_TAG_LONGS];
};
};
#define RADIX_TREE_INDEX_BITS (8 /* CHAR_BIT */ * sizeof(unsigned long))
-#define RADIX_TREE_MAX_PATH (RADIX_TREE_INDEX_BITS/RADIX_TREE_MAP_SHIFT + 2)
+#define RADIX_TREE_MAX_PATH (DIV_ROUND_UP(RADIX_TREE_INDEX_BITS, \
+ RADIX_TREE_MAP_SHIFT))
-static unsigned long height_to_maxindex[RADIX_TREE_MAX_PATH] __read_mostly;
+/*
+ * The height_to_maxindex array needs to be one deeper than the maximum
+ * path as height 0 holds only 1 entry.
+ */
+static unsigned long height_to_maxindex[RADIX_TREE_MAX_PATH + 1] __read_mostly;
/*
* Radix tree node cache.
*/
-static kmem_cache_t *radix_tree_node_cachep;
+static struct kmem_cache *radix_tree_node_cachep;
/*
* Per-cpu pool of preloaded nodes
int nr;
struct radix_tree_node *nodes[RADIX_TREE_MAX_PATH];
};
-DEFINE_PER_CPU(struct radix_tree_preload, radix_tree_preloads) = { 0, };
+static DEFINE_PER_CPU(struct radix_tree_preload, radix_tree_preloads) = { 0, };
+
+static inline gfp_t root_gfp_mask(struct radix_tree_root *root)
+{
+ return root->gfp_mask & __GFP_BITS_MASK;
+}
+
+static inline void tag_set(struct radix_tree_node *node, unsigned int tag,
+ int offset)
+{
+ __set_bit(offset, node->tags[tag]);
+}
+
+static inline void tag_clear(struct radix_tree_node *node, unsigned int tag,
+ int offset)
+{
+ __clear_bit(offset, node->tags[tag]);
+}
+
+static inline int tag_get(struct radix_tree_node *node, unsigned int tag,
+ int offset)
+{
+ return test_bit(offset, node->tags[tag]);
+}
+
+static inline void root_tag_set(struct radix_tree_root *root, unsigned int tag)
+{
+ root->gfp_mask |= (__force gfp_t)(1 << (tag + __GFP_BITS_SHIFT));
+}
+
+static inline void root_tag_clear(struct radix_tree_root *root, unsigned int tag)
+{
+ root->gfp_mask &= (__force gfp_t)~(1 << (tag + __GFP_BITS_SHIFT));
+}
+
+static inline void root_tag_clear_all(struct radix_tree_root *root)
+{
+ root->gfp_mask &= __GFP_BITS_MASK;
+}
+
+static inline int root_tag_get(struct radix_tree_root *root, unsigned int tag)
+{
+ return (__force unsigned)root->gfp_mask & (1 << (tag + __GFP_BITS_SHIFT));
+}
/*
+ * Returns 1 if any slot in the node has this tag set.
+ * Otherwise returns 0.
+ */
+static inline int any_tag_set(struct radix_tree_node *node, unsigned int tag)
+{
+ int idx;
+ for (idx = 0; idx < RADIX_TREE_TAG_LONGS; idx++) {
+ if (node->tags[tag][idx])
+ return 1;
+ }
+ return 0;
+}
+/*
* This assumes that the caller has performed appropriate preallocation, and
* that the caller has pinned this thread of control to the current CPU.
*/
static struct radix_tree_node *
radix_tree_node_alloc(struct radix_tree_root *root)
{
- struct radix_tree_node *ret;
+ struct radix_tree_node *ret = NULL;
+ gfp_t gfp_mask = root_gfp_mask(root);
- ret = kmem_cache_alloc(radix_tree_node_cachep, root->gfp_mask);
- if (ret == NULL && !(root->gfp_mask & __GFP_WAIT)) {
+ if (!(gfp_mask & __GFP_WAIT)) {
struct radix_tree_preload *rtp;
+ /*
+ * Provided the caller has preloaded here, we will always
+ * succeed in getting a node here (and never reach
+ * kmem_cache_alloc)
+ */
rtp = &__get_cpu_var(radix_tree_preloads);
if (rtp->nr) {
ret = rtp->nodes[rtp->nr - 1];
rtp->nr--;
}
}
+ if (ret == NULL)
+ ret = kmem_cache_alloc(radix_tree_node_cachep, gfp_mask);
+
+ BUG_ON(radix_tree_is_indirect_ptr(ret));
return ret;
}
+static void radix_tree_node_rcu_free(struct rcu_head *head)
+{
+ struct radix_tree_node *node =
+ container_of(head, struct radix_tree_node, rcu_head);
+
+ /*
+ * must only free zeroed nodes into the slab. radix_tree_shrink
+ * can leave us with a non-NULL entry in the first slot, so clear
+ * that here to make sure.
+ */
+ tag_clear(node, 0, 0);
+ tag_clear(node, 1, 0);
+ node->slots[0] = NULL;
+ node->count = 0;
+
+ kmem_cache_free(radix_tree_node_cachep, node);
+}
+
static inline void
radix_tree_node_free(struct radix_tree_node *node)
{
- kmem_cache_free(radix_tree_node_cachep, node);
+ call_rcu(&node->rcu_head, radix_tree_node_rcu_free);
}
/*
* ensure that the addition of a single element in the tree cannot fail. On
* success, return zero, with preemption disabled. On error, return -ENOMEM
* with preemption not disabled.
+ *
+ * To make use of this facility, the radix tree must be initialised without
+ * __GFP_WAIT being passed to INIT_RADIX_TREE().
*/
int radix_tree_preload(gfp_t gfp_mask)
{
out:
return ret;
}
-
-static inline void tag_set(struct radix_tree_node *node, unsigned int tag,
- int offset)
-{
- __set_bit(offset, node->tags[tag]);
-}
-
-static inline void tag_clear(struct radix_tree_node *node, unsigned int tag,
- int offset)
-{
- __clear_bit(offset, node->tags[tag]);
-}
-
-static inline int tag_get(struct radix_tree_node *node, unsigned int tag,
- int offset)
-{
- return test_bit(offset, node->tags[tag]);
-}
-
-/*
- * Returns 1 if any slot in the node has this tag set.
- * Otherwise returns 0.
- */
-static inline int any_tag_set(struct radix_tree_node *node, unsigned int tag)
-{
- int idx;
- for (idx = 0; idx < RADIX_TREE_TAG_LONGS; idx++) {
- if (node->tags[tag][idx])
- return 1;
- }
- return 0;
-}
+EXPORT_SYMBOL(radix_tree_preload);
/*
* Return the maximum key which can be store into a
{
struct radix_tree_node *node;
unsigned int height;
- char tags[RADIX_TREE_MAX_TAGS];
int tag;
/* Figure out what the height should be. */
goto out;
}
- /*
- * Prepare the tag status of the top-level node for propagation
- * into the newly-pushed top-level node(s)
- */
- for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) {
- tags[tag] = 0;
- if (any_tag_set(root->rnode, tag))
- tags[tag] = 1;
- }
-
do {
+ unsigned int newheight;
if (!(node = radix_tree_node_alloc(root)))
return -ENOMEM;
/* Increase the height. */
- node->slots[0] = root->rnode;
+ node->slots[0] = radix_tree_indirect_to_ptr(root->rnode);
/* Propagate the aggregated tag info into the new root */
for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) {
- if (tags[tag])
+ if (root_tag_get(root, tag))
tag_set(node, tag, 0);
}
+ newheight = root->height+1;
+ node->height = newheight;
node->count = 1;
- root->rnode = node;
- root->height++;
+ node = radix_tree_ptr_to_indirect(node);
+ rcu_assign_pointer(root->rnode, node);
+ root->height = newheight;
} while (height > root->height);
out:
return 0;
int offset;
int error;
+ BUG_ON(radix_tree_is_indirect_ptr(item));
+
/* Make sure the tree is high enough. */
- if ((!index && !root->rnode) ||
- index > radix_tree_maxindex(root->height)) {
+ if (index > radix_tree_maxindex(root->height)) {
error = radix_tree_extend(root, index);
if (error)
return error;
}
- slot = root->rnode;
+ slot = radix_tree_indirect_to_ptr(root->rnode);
+
height = root->height;
shift = (height-1) * RADIX_TREE_MAP_SHIFT;
offset = 0; /* uninitialised var warning */
- do {
+ while (height > 0) {
if (slot == NULL) {
/* Have to add a child node. */
if (!(slot = radix_tree_node_alloc(root)))
return -ENOMEM;
+ slot->height = height;
if (node) {
- node->slots[offset] = slot;
+ rcu_assign_pointer(node->slots[offset], slot);
node->count++;
} else
- root->rnode = slot;
+ rcu_assign_pointer(root->rnode,
+ radix_tree_ptr_to_indirect(slot));
}
/* Go a level down */
slot = node->slots[offset];
shift -= RADIX_TREE_MAP_SHIFT;
height--;
- } while (height > 0);
+ }
if (slot != NULL)
return -EEXIST;
- BUG_ON(!node);
- node->count++;
- node->slots[offset] = item;
- BUG_ON(tag_get(node, 0, offset));
- BUG_ON(tag_get(node, 1, offset));
+ if (node) {
+ node->count++;
+ rcu_assign_pointer(node->slots[offset], item);
+ BUG_ON(tag_get(node, 0, offset));
+ BUG_ON(tag_get(node, 1, offset));
+ } else {
+ rcu_assign_pointer(root->rnode, item);
+ BUG_ON(root_tag_get(root, 0));
+ BUG_ON(root_tag_get(root, 1));
+ }
return 0;
}
EXPORT_SYMBOL(radix_tree_insert);
-static inline void **__lookup_slot(struct radix_tree_root *root,
- unsigned long index)
+/*
+ * is_slot == 1 : search for the slot.
+ * is_slot == 0 : search for the node.
+ */
+static void *radix_tree_lookup_element(struct radix_tree_root *root,
+ unsigned long index, int is_slot)
{
unsigned int height, shift;
- struct radix_tree_node **slot;
+ struct radix_tree_node *node, **slot;
- height = root->height;
+ node = rcu_dereference(root->rnode);
+ if (node == NULL)
+ return NULL;
+
+ if (!radix_tree_is_indirect_ptr(node)) {
+ if (index > 0)
+ return NULL;
+ return is_slot ? (void *)&root->rnode : node;
+ }
+ node = radix_tree_indirect_to_ptr(node);
+
+ height = node->height;
if (index > radix_tree_maxindex(height))
return NULL;
shift = (height-1) * RADIX_TREE_MAP_SHIFT;
- slot = &root->rnode;
- while (height > 0) {
- if (*slot == NULL)
+ do {
+ slot = (struct radix_tree_node **)
+ (node->slots + ((index>>shift) & RADIX_TREE_MAP_MASK));
+ node = rcu_dereference(*slot);
+ if (node == NULL)
return NULL;
- slot = (struct radix_tree_node **)
- ((*slot)->slots +
- ((index >> shift) & RADIX_TREE_MAP_MASK));
shift -= RADIX_TREE_MAP_SHIFT;
height--;
- }
+ } while (height > 0);
- return (void **)slot;
+ return is_slot ? (void *)slot:node;
}
/**
* @root: radix tree root
* @index: index key
*
- * Lookup the slot corresponding to the position @index in the radix tree
- * @root. This is useful for update-if-exists operations.
+ * Returns: the slot corresponding to the position @index in the
+ * radix tree @root. This is useful for update-if-exists operations.
+ *
+ * This function can be called under rcu_read_lock iff the slot is not
+ * modified by radix_tree_replace_slot, otherwise it must be called
+ * exclusive from other writers. Any dereference of the slot must be done
+ * using radix_tree_deref_slot.
*/
void **radix_tree_lookup_slot(struct radix_tree_root *root, unsigned long index)
{
- return __lookup_slot(root, index);
+ return (void **)radix_tree_lookup_element(root, index, 1);
}
EXPORT_SYMBOL(radix_tree_lookup_slot);
* @index: index key
*
* Lookup the item at the position @index in the radix tree @root.
+ *
+ * This function can be called under rcu_read_lock, however the caller
+ * must manage lifetimes of leaf nodes (eg. RCU may also be used to free
+ * them safely). No RCU barriers are required to access or modify the
+ * returned item, however.
*/
void *radix_tree_lookup(struct radix_tree_root *root, unsigned long index)
{
- void **slot;
-
- slot = __lookup_slot(root, index);
- return slot != NULL ? *slot : NULL;
+ return radix_tree_lookup_element(root, index, 0);
}
EXPORT_SYMBOL(radix_tree_lookup);
struct radix_tree_node *slot;
height = root->height;
- if (index > radix_tree_maxindex(height))
- return NULL;
+ BUG_ON(index > radix_tree_maxindex(height));
+ slot = radix_tree_indirect_to_ptr(root->rnode);
shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
- slot = root->rnode;
while (height > 0) {
int offset;
height--;
}
+ /* set the root's tag bit */
+ if (slot && !root_tag_get(root, tag))
+ root_tag_set(root, tag);
+
return slot;
}
EXPORT_SYMBOL(radix_tree_tag_set);
void *radix_tree_tag_clear(struct radix_tree_root *root,
unsigned long index, unsigned int tag)
{
- struct radix_tree_path path[RADIX_TREE_MAX_PATH], *pathp = path;
- struct radix_tree_node *slot;
+ /*
+ * The radix tree path needs to be one longer than the maximum path
+ * since the "list" is null terminated.
+ */
+ struct radix_tree_path path[RADIX_TREE_MAX_PATH + 1], *pathp = path;
+ struct radix_tree_node *slot = NULL;
unsigned int height, shift;
- void *ret = NULL;
height = root->height;
if (index > radix_tree_maxindex(height))
shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
pathp->node = NULL;
- slot = root->rnode;
+ slot = radix_tree_indirect_to_ptr(root->rnode);
while (height > 0) {
int offset;
height--;
}
- ret = slot;
- if (ret == NULL)
+ if (slot == NULL)
goto out;
- do {
+ while (pathp->node) {
if (!tag_get(pathp->node, tag, pathp->offset))
goto out;
tag_clear(pathp->node, tag, pathp->offset);
if (any_tag_set(pathp->node, tag))
goto out;
pathp--;
- } while (pathp->node);
+ }
+
+ /* clear the root's tag bit */
+ if (root_tag_get(root, tag))
+ root_tag_clear(root, tag);
+
out:
- return ret;
+ return slot;
}
EXPORT_SYMBOL(radix_tree_tag_clear);
-#ifndef __KERNEL__ /* Only the test harness uses this at present */
/**
* radix_tree_tag_get - get a tag on a radix tree node
* @root: radix tree root
*
* Return values:
*
- * 0: tag not present
- * 1: tag present, set
- * -1: tag present, unset
+ * 0: tag not present or not set
+ * 1: tag set
*/
int radix_tree_tag_get(struct radix_tree_root *root,
unsigned long index, unsigned int tag)
{
unsigned int height, shift;
- struct radix_tree_node *slot;
+ struct radix_tree_node *node;
int saw_unset_tag = 0;
- height = root->height;
+ /* check the root's tag bit */
+ if (!root_tag_get(root, tag))
+ return 0;
+
+ node = rcu_dereference(root->rnode);
+ if (node == NULL)
+ return 0;
+
+ if (!radix_tree_is_indirect_ptr(node))
+ return (index == 0);
+ node = radix_tree_indirect_to_ptr(node);
+
+ height = node->height;
if (index > radix_tree_maxindex(height))
return 0;
shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
- slot = root->rnode;
for ( ; ; ) {
int offset;
- if (slot == NULL)
+ if (node == NULL)
return 0;
offset = (index >> shift) & RADIX_TREE_MAP_MASK;
* 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(node, tag, offset))
saw_unset_tag = 1;
if (height == 1) {
- int ret = tag_get(slot, tag, offset);
+ int ret = tag_get(node, tag, offset);
BUG_ON(ret && saw_unset_tag);
- return ret ? 1 : -1;
+ return !!ret;
}
- slot = slot->slots[offset];
+ node = rcu_dereference(node->slots[offset]);
shift -= RADIX_TREE_MAP_SHIFT;
height--;
}
}
EXPORT_SYMBOL(radix_tree_tag_get);
-#endif
+
+/**
+ * radix_tree_next_hole - find the next hole (not-present entry)
+ * @root: tree root
+ * @index: index key
+ * @max_scan: maximum range to search
+ *
+ * Search the set [index, min(index+max_scan-1, MAX_INDEX)] for the lowest
+ * indexed hole.
+ *
+ * Returns: the index of the hole if found, otherwise returns an index
+ * outside of the set specified (in which case 'return - index >= max_scan'
+ * will be true). In rare cases of index wrap-around, 0 will be returned.
+ *
+ * radix_tree_next_hole may be called under rcu_read_lock. However, like
+ * radix_tree_gang_lookup, this will not atomically search a snapshot of
+ * the tree at a single point in time. For example, if a hole is created
+ * at index 5, then subsequently a hole is created at index 10,
+ * radix_tree_next_hole covering both indexes may return 10 if called
+ * under rcu_read_lock.
+ */
+unsigned long radix_tree_next_hole(struct radix_tree_root *root,
+ unsigned long index, unsigned long max_scan)
+{
+ unsigned long i;
+
+ for (i = 0; i < max_scan; i++) {
+ if (!radix_tree_lookup(root, index))
+ break;
+ index++;
+ if (index == 0)
+ break;
+ }
+
+ return index;
+}
+EXPORT_SYMBOL(radix_tree_next_hole);
+
+/**
+ * radix_tree_prev_hole - find the prev hole (not-present entry)
+ * @root: tree root
+ * @index: index key
+ * @max_scan: maximum range to search
+ *
+ * Search backwards in the range [max(index-max_scan+1, 0), index]
+ * for the first hole.
+ *
+ * Returns: the index of the hole if found, otherwise returns an index
+ * outside of the set specified (in which case 'index - return >= max_scan'
+ * will be true). In rare cases of wrap-around, LONG_MAX will be returned.
+ *
+ * radix_tree_next_hole may be called under rcu_read_lock. However, like
+ * radix_tree_gang_lookup, this will not atomically search a snapshot of
+ * the tree at a single point in time. For example, if a hole is created
+ * at index 10, then subsequently a hole is created at index 5,
+ * radix_tree_prev_hole covering both indexes may return 5 if called under
+ * rcu_read_lock.
+ */
+unsigned long radix_tree_prev_hole(struct radix_tree_root *root,
+ unsigned long index, unsigned long max_scan)
+{
+ unsigned long i;
+
+ for (i = 0; i < max_scan; i++) {
+ if (!radix_tree_lookup(root, index))
+ break;
+ index--;
+ if (index == LONG_MAX)
+ break;
+ }
+
+ return index;
+}
+EXPORT_SYMBOL(radix_tree_prev_hole);
static unsigned int
-__lookup(struct radix_tree_root *root, void **results, unsigned long index,
+__lookup(struct radix_tree_node *slot, void ***results, unsigned long index,
unsigned int max_items, unsigned long *next_index)
{
unsigned int nr_found = 0;
unsigned int shift, height;
- struct radix_tree_node *slot;
unsigned long i;
- height = root->height;
+ height = slot->height;
if (height == 0)
goto out;
-
shift = (height-1) * RADIX_TREE_MAP_SHIFT;
- slot = root->rnode;
for ( ; height > 1; height--) {
-
- for (i = (index >> shift) & RADIX_TREE_MAP_MASK ;
- i < RADIX_TREE_MAP_SIZE; i++) {
+ i = (index >> shift) & RADIX_TREE_MAP_MASK;
+ for (;;) {
if (slot->slots[i] != NULL)
break;
index &= ~((1UL << shift) - 1);
index += 1UL << shift;
if (index == 0)
goto out; /* 32-bit wraparound */
+ i++;
+ if (i == RADIX_TREE_MAP_SIZE)
+ goto out;
}
- if (i == RADIX_TREE_MAP_SIZE)
- goto out;
shift -= RADIX_TREE_MAP_SHIFT;
- slot = slot->slots[i];
+ slot = rcu_dereference(slot->slots[i]);
+ if (slot == NULL)
+ goto out;
}
/* 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];
+ results[nr_found++] = &(slot->slots[i]);
if (nr_found == max_items)
goto out;
}
* *@results.
*
* The implementation is naive.
+ *
+ * Like radix_tree_lookup, radix_tree_gang_lookup may be called under
+ * rcu_read_lock. In this case, rather than the returned results being
+ * an atomic snapshot of the tree at a single point in time, the semantics
+ * of an RCU protected gang lookup are as though multiple radix_tree_lookups
+ * have been issued in individual locks, and results stored in 'results'.
*/
unsigned int
radix_tree_gang_lookup(struct radix_tree_root *root, void **results,
unsigned long first_index, unsigned int max_items)
{
- const unsigned long max_index = radix_tree_maxindex(root->height);
+ unsigned long max_index;
+ struct radix_tree_node *node;
unsigned long cur_index = first_index;
- unsigned int ret = 0;
+ unsigned int ret;
+
+ node = rcu_dereference(root->rnode);
+ if (!node)
+ return 0;
+
+ if (!radix_tree_is_indirect_ptr(node)) {
+ if (first_index > 0)
+ return 0;
+ results[0] = node;
+ return 1;
+ }
+ node = radix_tree_indirect_to_ptr(node);
+
+ max_index = radix_tree_maxindex(node->height);
+ ret = 0;
while (ret < max_items) {
- unsigned int nr_found;
+ unsigned int nr_found, slots_found, i;
unsigned long next_index; /* Index of next search */
if (cur_index > max_index)
break;
- nr_found = __lookup(root, results + ret, cur_index,
+ slots_found = __lookup(node, (void ***)results + ret, cur_index,
max_items - ret, &next_index);
+ nr_found = 0;
+ for (i = 0; i < slots_found; i++) {
+ struct radix_tree_node *slot;
+ slot = *(((void ***)results)[ret + i]);
+ if (!slot)
+ continue;
+ results[ret + nr_found] = rcu_dereference(slot);
+ nr_found++;
+ }
ret += nr_found;
if (next_index == 0)
break;
cur_index = next_index;
}
+
return ret;
}
EXPORT_SYMBOL(radix_tree_gang_lookup);
+/**
+ * radix_tree_gang_lookup_slot - perform multiple slot lookup on radix tree
+ * @root: radix tree root
+ * @results: where the results of the lookup are placed
+ * @first_index: start the lookup from this key
+ * @max_items: place up to this many items at *results
+ *
+ * Performs an index-ascending scan of the tree for present items. Places
+ * their slots at *@results and returns the number of items which were
+ * placed at *@results.
+ *
+ * The implementation is naive.
+ *
+ * Like radix_tree_gang_lookup as far as RCU and locking goes. Slots must
+ * be dereferenced with radix_tree_deref_slot, and if using only RCU
+ * protection, radix_tree_deref_slot may fail requiring a retry.
+ */
+unsigned int
+radix_tree_gang_lookup_slot(struct radix_tree_root *root, void ***results,
+ unsigned long first_index, unsigned int max_items)
+{
+ unsigned long max_index;
+ struct radix_tree_node *node;
+ unsigned long cur_index = first_index;
+ unsigned int ret;
+
+ node = rcu_dereference(root->rnode);
+ if (!node)
+ return 0;
+
+ if (!radix_tree_is_indirect_ptr(node)) {
+ if (first_index > 0)
+ return 0;
+ results[0] = (void **)&root->rnode;
+ return 1;
+ }
+ node = radix_tree_indirect_to_ptr(node);
+
+ max_index = radix_tree_maxindex(node->height);
+
+ ret = 0;
+ while (ret < max_items) {
+ unsigned int slots_found;
+ unsigned long next_index; /* Index of next search */
+
+ if (cur_index > max_index)
+ break;
+ slots_found = __lookup(node, results + ret, cur_index,
+ max_items - ret, &next_index);
+ ret += slots_found;
+ if (next_index == 0)
+ break;
+ cur_index = next_index;
+ }
+
+ return ret;
+}
+EXPORT_SYMBOL(radix_tree_gang_lookup_slot);
+
/*
* FIXME: the two tag_get()s here should use find_next_bit() instead of
* open-coding the search.
*/
static unsigned int
-__lookup_tag(struct radix_tree_root *root, void **results, unsigned long index,
+__lookup_tag(struct radix_tree_node *slot, void ***results, unsigned long index,
unsigned int max_items, unsigned long *next_index, unsigned int tag)
{
unsigned int nr_found = 0;
- unsigned int shift;
- unsigned int height = root->height;
- struct radix_tree_node *slot;
+ unsigned int shift, height;
- shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
- slot = root->rnode;
+ height = slot->height;
+ if (height == 0)
+ goto out;
+ shift = (height-1) * RADIX_TREE_MAP_SHIFT;
while (height > 0) {
- unsigned long i = (index >> shift) & RADIX_TREE_MAP_MASK;
+ unsigned long i = (index >> shift) & RADIX_TREE_MAP_MASK ;
- for ( ; i < RADIX_TREE_MAP_SIZE; i++) {
- if (tag_get(slot, tag, i)) {
- BUG_ON(slot->slots[i] == NULL);
+ for (;;) {
+ if (tag_get(slot, tag, i))
break;
- }
index &= ~((1UL << shift) - 1);
index += 1UL << shift;
if (index == 0)
goto out; /* 32-bit wraparound */
+ i++;
+ if (i == RADIX_TREE_MAP_SIZE)
+ goto out;
}
- 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 (tag_get(slot, tag, j)) {
- BUG_ON(slot->slots[j] == NULL);
- results[nr_found++] = slot->slots[j];
+ if (!tag_get(slot, tag, j))
+ continue;
+ /*
+ * Even though the tag was found set, we need to
+ * recheck that we have a non-NULL node, because
+ * if this lookup is lockless, it may have been
+ * subsequently deleted.
+ *
+ * Similar care must be taken in any place that
+ * lookup ->slots[x] without a lock (ie. can't
+ * rely on its value remaining the same).
+ */
+ 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];
+ slot = rcu_dereference(slot->slots[i]);
+ if (slot == NULL)
+ break;
}
out:
*next_index = index;
unsigned long first_index, unsigned int max_items,
unsigned int tag)
{
- const unsigned long max_index = radix_tree_maxindex(root->height);
+ struct radix_tree_node *node;
+ unsigned long max_index;
unsigned long cur_index = first_index;
- unsigned int ret = 0;
+ unsigned int ret;
+
+ /* check the root's tag bit */
+ if (!root_tag_get(root, tag))
+ return 0;
+
+ node = rcu_dereference(root->rnode);
+ if (!node)
+ return 0;
+
+ if (!radix_tree_is_indirect_ptr(node)) {
+ if (first_index > 0)
+ return 0;
+ results[0] = node;
+ return 1;
+ }
+ node = radix_tree_indirect_to_ptr(node);
+
+ max_index = radix_tree_maxindex(node->height);
+ ret = 0;
while (ret < max_items) {
- unsigned int nr_found;
+ unsigned int nr_found, slots_found, i;
unsigned long next_index; /* Index of next search */
if (cur_index > max_index)
break;
- nr_found = __lookup_tag(root, results + ret, cur_index,
- max_items - ret, &next_index, tag);
+ slots_found = __lookup_tag(node, (void ***)results + ret,
+ cur_index, max_items - ret, &next_index, tag);
+ nr_found = 0;
+ for (i = 0; i < slots_found; i++) {
+ struct radix_tree_node *slot;
+ slot = *(((void ***)results)[ret + i]);
+ if (!slot)
+ continue;
+ results[ret + nr_found] = rcu_dereference(slot);
+ nr_found++;
+ }
ret += nr_found;
if (next_index == 0)
break;
cur_index = next_index;
}
+
return ret;
}
EXPORT_SYMBOL(radix_tree_gang_lookup_tag);
/**
+ * radix_tree_gang_lookup_tag_slot - perform multiple slot lookup on a
+ * radix tree based on a tag
+ * @root: radix tree root
+ * @results: where the results of the lookup are placed
+ * @first_index: start the lookup from this key
+ * @max_items: place up to this many items at *results
+ * @tag: the tag index (< RADIX_TREE_MAX_TAGS)
+ *
+ * Performs an index-ascending scan of the tree for present items which
+ * have the tag indexed by @tag set. Places the slots at *@results and
+ * returns the number of slots which were placed at *@results.
+ */
+unsigned int
+radix_tree_gang_lookup_tag_slot(struct radix_tree_root *root, void ***results,
+ unsigned long first_index, unsigned int max_items,
+ unsigned int tag)
+{
+ struct radix_tree_node *node;
+ unsigned long max_index;
+ unsigned long cur_index = first_index;
+ unsigned int ret;
+
+ /* check the root's tag bit */
+ if (!root_tag_get(root, tag))
+ return 0;
+
+ node = rcu_dereference(root->rnode);
+ if (!node)
+ return 0;
+
+ if (!radix_tree_is_indirect_ptr(node)) {
+ if (first_index > 0)
+ return 0;
+ results[0] = (void **)&root->rnode;
+ return 1;
+ }
+ node = radix_tree_indirect_to_ptr(node);
+
+ max_index = radix_tree_maxindex(node->height);
+
+ ret = 0;
+ while (ret < max_items) {
+ unsigned int slots_found;
+ unsigned long next_index; /* Index of next search */
+
+ if (cur_index > max_index)
+ break;
+ slots_found = __lookup_tag(node, results + ret,
+ cur_index, max_items - ret, &next_index, tag);
+ ret += slots_found;
+ if (next_index == 0)
+ break;
+ cur_index = next_index;
+ }
+
+ return ret;
+}
+EXPORT_SYMBOL(radix_tree_gang_lookup_tag_slot);
+
+
+/**
* radix_tree_shrink - shrink height of a radix tree to minimal
* @root radix tree root
*/
static inline void radix_tree_shrink(struct radix_tree_root *root)
{
/* try to shrink tree height */
- while (root->height > 1 &&
- root->rnode->count == 1 &&
- root->rnode->slots[0]) {
+ while (root->height > 0) {
struct radix_tree_node *to_free = root->rnode;
+ void *newptr;
+
+ BUG_ON(!radix_tree_is_indirect_ptr(to_free));
+ to_free = radix_tree_indirect_to_ptr(to_free);
- root->rnode = to_free->slots[0];
+ /*
+ * The candidate node has more than one child, or its child
+ * is not at the leftmost slot, we cannot shrink.
+ */
+ if (to_free->count != 1)
+ break;
+ if (!to_free->slots[0])
+ break;
+
+ /*
+ * We don't need rcu_assign_pointer(), since we are simply
+ * moving the node from one part of the tree to another. If
+ * it was safe to dereference the old pointer to it
+ * (to_free->slots[0]), it will be safe to dereference the new
+ * one (root->rnode).
+ */
+ newptr = to_free->slots[0];
+ if (root->height > 1)
+ newptr = radix_tree_ptr_to_indirect(newptr);
+ root->rnode = newptr;
root->height--;
- /* must only free zeroed nodes into the slab */
- tag_clear(to_free, 0, 0);
- tag_clear(to_free, 1, 0);
- to_free->slots[0] = NULL;
- to_free->count = 0;
radix_tree_node_free(to_free);
}
}
*/
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;
+ /*
+ * The radix tree path needs to be one longer than the maximum path
+ * since the "list" is null terminated.
+ */
+ struct radix_tree_path path[RADIX_TREE_MAX_PATH + 1], *pathp = path;
+ struct radix_tree_node *slot = NULL;
+ struct radix_tree_node *to_free;
unsigned int height, shift;
- void *ret = NULL;
- char tags[RADIX_TREE_MAX_TAGS];
- int nr_cleared_tags;
int tag;
int offset;
if (index > radix_tree_maxindex(height))
goto out;
+ slot = root->rnode;
+ if (height == 0) {
+ root_tag_clear_all(root);
+ root->rnode = NULL;
+ goto out;
+ }
+ slot = radix_tree_indirect_to_ptr(slot);
+
shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
pathp->node = NULL;
- slot = root->rnode;
- for ( ; height > 0; height--) {
+ do {
if (slot == NULL)
goto out;
pathp->node = slot;
slot = slot->slots[offset];
shift -= RADIX_TREE_MAP_SHIFT;
- }
+ height--;
+ } while (height > 0);
- ret = slot;
- if (ret == NULL)
+ if (slot == NULL)
goto out;
- orig_pathp = pathp;
-
/*
* Clear all tags associated with the just-deleted item
*/
- nr_cleared_tags = 0;
for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) {
- tags[tag] = 1;
- if (tag_get(pathp->node, tag, pathp->offset)) {
- tag_clear(pathp->node, tag, pathp->offset);
- if (!any_tag_set(pathp->node, tag)) {
- tags[tag] = 0;
- nr_cleared_tags++;
- }
- }
- }
-
- for (pathp--; nr_cleared_tags && pathp->node; pathp--) {
- for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) {
- if (tags[tag])
- continue;
-
- tag_clear(pathp->node, tag, pathp->offset);
- if (any_tag_set(pathp->node, tag)) {
- tags[tag] = 1;
- nr_cleared_tags--;
- }
- }
+ if (tag_get(pathp->node, tag, pathp->offset))
+ radix_tree_tag_clear(root, index, tag);
}
+ to_free = NULL;
/* Now free the nodes we do not need anymore */
- for (pathp = orig_pathp; pathp->node; pathp--) {
+ while (pathp->node) {
pathp->node->slots[pathp->offset] = NULL;
pathp->node->count--;
+ /*
+ * Queue the node for deferred freeing after the
+ * last reference to it disappears (set NULL, above).
+ */
+ if (to_free)
+ radix_tree_node_free(to_free);
if (pathp->node->count) {
- if (pathp->node == root->rnode)
+ if (pathp->node ==
+ radix_tree_indirect_to_ptr(root->rnode))
radix_tree_shrink(root);
goto out;
}
/* Node with zero slots in use so free it */
- radix_tree_node_free(pathp->node);
+ to_free = pathp->node;
+ pathp--;
+
}
- root->rnode = NULL;
+ root_tag_clear_all(root);
root->height = 0;
+ root->rnode = NULL;
+ if (to_free)
+ radix_tree_node_free(to_free);
+
out:
- return ret;
+ return slot;
}
EXPORT_SYMBOL(radix_tree_delete);
*/
int radix_tree_tagged(struct radix_tree_root *root, unsigned int tag)
{
- struct radix_tree_node *rnode;
- rnode = root->rnode;
- if (!rnode)
- return 0;
- return any_tag_set(rnode, tag);
+ return root_tag_get(root, tag);
}
EXPORT_SYMBOL(radix_tree_tagged);
static void
-radix_tree_node_ctor(void *node, kmem_cache_t *cachep, unsigned long flags)
+radix_tree_node_ctor(void *node)
{
memset(node, 0, sizeof(struct radix_tree_node));
}
static __init unsigned long __maxindex(unsigned int height)
{
- unsigned int tmp = height * RADIX_TREE_MAP_SHIFT;
- unsigned long index = (~0UL >> (RADIX_TREE_INDEX_BITS - tmp - 1)) >> 1;
-
- if (tmp >= RADIX_TREE_INDEX_BITS)
- index = ~0UL;
- return index;
+ unsigned int width = height * RADIX_TREE_MAP_SHIFT;
+ int shift = RADIX_TREE_INDEX_BITS - width;
+
+ if (shift < 0)
+ return ~0UL;
+ if (shift >= BITS_PER_LONG)
+ return 0UL;
+ return ~0UL >> shift;
}
static __init void radix_tree_init_maxindex(void)
height_to_maxindex[i] = __maxindex(i);
}
-#ifdef CONFIG_HOTPLUG_CPU
static int radix_tree_callback(struct notifier_block *nfb,
unsigned long action,
void *hcpu)
struct radix_tree_preload *rtp;
/* Free per-cpu pool of perloaded nodes */
- if (action == CPU_DEAD) {
+ if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) {
rtp = &per_cpu(radix_tree_preloads, cpu);
while (rtp->nr) {
kmem_cache_free(radix_tree_node_cachep,
}
return NOTIFY_OK;
}
-#endif /* CONFIG_HOTPLUG_CPU */
void __init radix_tree_init(void)
{
radix_tree_node_cachep = kmem_cache_create("radix_tree_node",
sizeof(struct radix_tree_node), 0,
- SLAB_PANIC, radix_tree_node_ctor, NULL);
+ SLAB_PANIC | SLAB_RECLAIM_ACCOUNT,
+ radix_tree_node_ctor);
radix_tree_init_maxindex();
hotcpu_notifier(radix_tree_callback, 0);
}
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff