Release 4.9 lib/radix-tree.c

/*
 * Copyright (C) 2001 Momchil Velikov
 * Portions Copyright (C) 2001 Christoph Hellwig
 * Copyright (C) 2005 SGI, Christoph Lameter
 * Copyright (C) 2006 Nick Piggin
 * Copyright (C) 2012 Konstantin Khlebnikov
 * Copyright (C) 2016 Intel, Matthew Wilcox
 * Copyright (C) 2016 Intel, Ross Zwisler
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2, or (at
 * your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include <linux/errno.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/export.h>
#include <linux/radix-tree.h>
#include <linux/percpu.h>
#include <linux/slab.h>
#include <linux/kmemleak.h>
#include <linux/notifier.h>
#include <linux/cpu.h>
#include <linux/string.h>
#include <linux/bitops.h>
#include <linux/rcupdate.h>
#include <linux/preempt.h>		/* in_interrupt() */


/* Number of nodes in fully populated tree of given height */

static unsigned long height_to_maxnodes[RADIX_TREE_MAX_PATH + 1] __read_mostly;

/*
 * Radix tree node cache.
 */

static struct kmem_cache *radix_tree_node_cachep;

/*
 * The radix tree is variable-height, so an insert operation not only has
 * to build the branch to its corresponding item, it also has to build the
 * branch to existing items if the size has to be increased (by
 * radix_tree_extend).
 *
 * The worst case is a zero height tree with just a single item at index 0,
 * and then inserting an item at index ULONG_MAX. This requires 2 new branches
 * of RADIX_TREE_MAX_PATH size to be created, with only the root node shared.
 * Hence:
 */

#define RADIX_TREE_PRELOAD_SIZE (RADIX_TREE_MAX_PATH * 2 - 1)

/*
 * Per-cpu pool of preloaded nodes
 */

struct radix_tree_preload {
	
unsigned nr;
	/* nodes->private_data points to next preallocated node */
	
struct radix_tree_node *nodes;
};
static DEFINE_PER_CPU(struct radix_tree_preload, radix_tree_preloads) = { 0, };



static inline void *node_to_entry(void *ptr)
{
	return (void *)((unsigned long)ptr | RADIX_TREE_INTERNAL_NODE);
}

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#define RADIX_TREE_RETRY	node_to_entry(NULL)

#ifdef CONFIG_RADIX_TREE_MULTIORDER
/* Sibling slots point directly to another slot in the same node */


static inline bool is_sibling_entry(struct radix_tree_node *parent, void *node)
{
	void **ptr = node;
	return (parent->slots <= ptr) &&
			(ptr < parent->slots + RADIX_TREE_MAP_SIZE);
}
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#else


static inline bool is_sibling_entry(struct radix_tree_node *parent, void *node)
{
	return false;
}
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#endif



static inline unsigned long get_slot_offset(struct radix_tree_node *parent,
						 void **slot)
{
	return slot - parent->slots;
}

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static unsigned int radix_tree_descend(struct radix_tree_node *parent,
			struct radix_tree_node **nodep, unsigned long index)
{
	unsigned int offset = (index >> parent->shift) & RADIX_TREE_MAP_MASK;
	void **entry = rcu_dereference_raw(parent->slots[offset]);

#ifdef CONFIG_RADIX_TREE_MULTIORDER
	if (radix_tree_is_internal_node(entry)) {
		if (is_sibling_entry(parent, entry)) {
			void **sibentry = (void **) entry_to_node(entry);
			offset = get_slot_offset(parent, sibentry);
			entry = rcu_dereference_raw(*sibentry);
		}
	}
#endif

	*nodep = (void *)entry;
	return offset;
}

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static inline gfp_t root_gfp_mask(struct radix_tree_root *root)
{
	return root->gfp_mask & __GFP_BITS_MASK;
}

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static inline void tag_set(struct radix_tree_node *node, unsigned int tag,
		int offset)
{
	__set_bit(offset, node->tags[tag]);
}

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static inline void tag_clear(struct radix_tree_node *node, unsigned int tag,
		int offset)
{
	__clear_bit(offset, node->tags[tag]);
}

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static inline int tag_get(struct radix_tree_node *node, unsigned int tag,
		int offset)
{
	return test_bit(offset, node->tags[tag]);
}

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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));
}

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static inline void root_tag_clear(struct radix_tree_root *root, unsigned tag)
{
	root->gfp_mask &= (__force gfp_t)~(1 << (tag + __GFP_BITS_SHIFT));
}

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static inline void root_tag_clear_all(struct radix_tree_root *root)
{
	root->gfp_mask &= __GFP_BITS_MASK;
}

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static inline int root_tag_get(struct radix_tree_root *root, unsigned int tag)
{
	return (__force int)root->gfp_mask & (1 << (tag + __GFP_BITS_SHIFT));
}

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static inline unsigned root_tags_get(struct radix_tree_root *root)
{
	return (__force unsigned)root->gfp_mask >> __GFP_BITS_SHIFT;
}

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/*
 * 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)
{
	unsigned idx;
	for (idx = 0; idx < RADIX_TREE_TAG_LONGS; idx++) {
		if (node->tags[tag][idx])
			return 1;
	}
	return 0;
}

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/**
 * radix_tree_find_next_bit - find the next set bit in a memory region
 *
 * @addr: The address to base the search on
 * @size: The bitmap size in bits
 * @offset: The bitnumber to start searching at
 *
 * Unrollable variant of find_next_bit() for constant size arrays.
 * Tail bits starting from size to roundup(size, BITS_PER_LONG) must be zero.
 * Returns next bit offset, or size if nothing found.
 */

static __always_inline unsigned long

radix_tree_find_next_bit(const unsigned long *addr,
			 unsigned long size, unsigned long offset)
{
	if (!__builtin_constant_p(size))
		return find_next_bit(addr, size, offset);

	if (offset < size) {
		unsigned long tmp;

		addr += offset / BITS_PER_LONG;
		tmp = *addr >> (offset % BITS_PER_LONG);
		if (tmp)
			return __ffs(tmp) + offset;
		offset = (offset + BITS_PER_LONG) & ~(BITS_PER_LONG - 1);
		while (offset < size) {
			tmp = *++addr;
			if (tmp)
				return __ffs(tmp) + offset;
			offset += BITS_PER_LONG;
		}
	}
	return size;
}

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#ifndef __KERNEL__


static void dump_node(struct radix_tree_node *node, unsigned long index)
{
	unsigned long i;

	pr_debug("radix node: %p offset %d tags %lx %lx %lx shift %d count %d parent %p\n",
		node, node->offset,
		node->tags[0][0], node->tags[1][0], node->tags[2][0],
		node->shift, node->count, node->parent);

	for (i = 0; i < RADIX_TREE_MAP_SIZE; i++) {
		unsigned long first = index | (i << node->shift);
		unsigned long last = first | ((1UL << node->shift) - 1);
		void *entry = node->slots[i];
		if (!entry)
			continue;
		if (is_sibling_entry(node, entry)) {
			pr_debug("radix sblng %p offset %ld val %p indices %ld-%ld\n",
					entry, i,
					*(void **)entry_to_node(entry),
					first, last);
		} else if (!radix_tree_is_internal_node(entry)) {
			pr_debug("radix entry %p offset %ld indices %ld-%ld\n",
					entry, i, first, last);
		} else {
			dump_node(entry_to_node(entry), first);
		}
	}
}

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/* For debug */


static void radix_tree_dump(struct radix_tree_root *root)
{
	pr_debug("radix root: %p rnode %p tags %x\n",
			root, root->rnode,
			root->gfp_mask >> __GFP_BITS_SHIFT);
	if (!radix_tree_is_internal_node(root->rnode))
		return;
	dump_node(entry_to_node(root->rnode), 0);
}
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#endif

/*
 * 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 = NULL;
	gfp_t gfp_mask = root_gfp_mask(root);

	/*
         * Preload code isn't irq safe and it doesn't make sense to use
         * preloading during an interrupt anyway as all the allocations have
         * to be atomic. So just do normal allocation when in interrupt.
         */
	if (!gfpflags_allow_blocking(gfp_mask) && !in_interrupt()) {
		struct radix_tree_preload *rtp;

		/*
                 * Even if the caller has preloaded, try to allocate from the
                 * cache first for the new node to get accounted to the memory
                 * cgroup.
                 */
		ret = kmem_cache_alloc(radix_tree_node_cachep,
				       gfp_mask | __GFP_NOWARN);
		if (ret)
			goto out;

		/*
                 * Provided the caller has preloaded here, we will always
                 * succeed in getting a node here (and never reach
                 * kmem_cache_alloc)
                 */
		rtp = this_cpu_ptr(&radix_tree_preloads);
		if (rtp->nr) {
			ret = rtp->nodes;
			rtp->nodes = ret->private_data;
			ret->private_data = NULL;
			rtp->nr--;
		}
		/*
                 * Update the allocation stack trace as this is more useful
                 * for debugging.
                 */
		kmemleak_update_trace(ret);
		goto out;
	}
	ret = kmem_cache_alloc(radix_tree_node_cachep, gfp_mask);
out:
	BUG_ON(radix_tree_is_internal_node(ret));
	return ret;
}

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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);
	int i;

	/*
         * 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.
         */
	for (i = 0; i < RADIX_TREE_MAX_TAGS; i++)
		tag_clear(node, i, 0);

	node->slots[0] = NULL;
	node->count = 0;

	kmem_cache_free(radix_tree_node_cachep, node);
}

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static inline void

radix_tree_node_free(struct radix_tree_node *node)
{
	call_rcu(&node->rcu_head, radix_tree_node_rcu_free);
}

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/*
 * Load up this CPU's radix_tree_node buffer with sufficient objects to
 * 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_DIRECT_RECLAIM being passed to INIT_RADIX_TREE().
 */


static int __radix_tree_preload(gfp_t gfp_mask, int nr)
{
	struct radix_tree_preload *rtp;
	struct radix_tree_node *node;
	int ret = -ENOMEM;

	/*
         * Nodes preloaded by one cgroup can be be used by another cgroup, so
         * they should never be accounted to any particular memory cgroup.
         */
	gfp_mask &= ~__GFP_ACCOUNT;

	preempt_disable();
	rtp = this_cpu_ptr(&radix_tree_preloads);
	while (rtp->nr < nr) {
		preempt_enable();
		node = kmem_cache_alloc(radix_tree_node_cachep, gfp_mask);
		if (node == NULL)
			goto out;
		preempt_disable();
		rtp = this_cpu_ptr(&radix_tree_preloads);
		if (rtp->nr < nr) {
			node->private_data = rtp->nodes;
			rtp->nodes = node;
			rtp->nr++;
		} else {
			kmem_cache_free(radix_tree_node_cachep, node);
		}
	}
	ret = 0;
out:
	return ret;
}

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/*
 * Load up this CPU's radix_tree_node buffer with sufficient objects to
 * 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_DIRECT_RECLAIM being passed to INIT_RADIX_TREE().
 */


int radix_tree_preload(gfp_t gfp_mask)
{
	/* Warn on non-sensical use... */
	WARN_ON_ONCE(!gfpflags_allow_blocking(gfp_mask));
	return __radix_tree_preload(gfp_mask, RADIX_TREE_PRELOAD_SIZE);
}
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EXPORT_SYMBOL(radix_tree_preload);

/*
 * The same as above function, except we don't guarantee preloading happens.
 * We do it, if we decide it helps. On success, return zero with preemption
 * disabled. On error, return -ENOMEM with preemption not disabled.
 */


int radix_tree_maybe_preload(gfp_t gfp_mask)
{
	if (gfpflags_allow_blocking(gfp_mask))
		return __radix_tree_preload(gfp_mask, RADIX_TREE_PRELOAD_SIZE);
	/* Preloading doesn't help anything with this gfp mask, skip it */
	preempt_disable();
	return 0;
}
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EXPORT_SYMBOL(radix_tree_maybe_preload);

/*
 * The same as function above, but preload number of nodes required to insert
 * (1 << order) continuous naturally-aligned elements.
 */


int radix_tree_maybe_preload_order(gfp_t gfp_mask, int order)
{
	unsigned long nr_subtrees;
	int nr_nodes, subtree_height;

	/* Preloading doesn't help anything with this gfp mask, skip it */
	if (!gfpflags_allow_blocking(gfp_mask)) {
		preempt_disable();
		return 0;
	}

	/*
         * Calculate number and height of fully populated subtrees it takes to
         * store (1 << order) elements.
         */
	nr_subtrees = 1 << order;
	for (subtree_height = 0; nr_subtrees > RADIX_TREE_MAP_SIZE;
			subtree_height++)
		nr_subtrees >>= RADIX_TREE_MAP_SHIFT;

	/*
         * The worst case is zero height tree with a single item at index 0 and
         * then inserting items starting at ULONG_MAX - (1 << order).
         *
         * This requires RADIX_TREE_MAX_PATH nodes to build branch from root to
         * 0-index item.
         */
	nr_nodes = RADIX_TREE_MAX_PATH;

	/* Plus branch to fully populated subtrees. */
	nr_nodes += RADIX_TREE_MAX_PATH - subtree_height;

	/* Root node is shared. */
	nr_nodes--;

	/* Plus nodes required to build subtrees. */
	nr_nodes += nr_subtrees * height_to_maxnodes[subtree_height];

	return __radix_tree_preload(gfp_mask, nr_nodes);
}

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/*
 * The maximum index which can be stored in a radix tree
 */


static inline unsigned long shift_maxindex(unsigned int shift)
{
	return (RADIX_TREE_MAP_SIZE << shift) - 1;
}

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static inline unsigned long node_maxindex(struct radix_tree_node *node)
{
	return shift_maxindex(node->shift);
}

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static unsigned radix_tree_load_root(struct radix_tree_root *root,
		struct radix_tree_node **nodep, unsigned long *maxindex)
{
	struct radix_tree_node *node = rcu_dereference_raw(root->rnode);

	*nodep = node;

	if (likely(radix_tree_is_internal_node(node))) {
		node = entry_to_node(node);
		*maxindex = node_maxindex(node);
		return node->shift + RADIX_TREE_MAP_SHIFT;
	}

	*maxindex = 0;
	return 0;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
matthew wilcox
matthew wilcox
81
100.00%
4
100.00%
Total
81
100.00%
4
100.00%

/*
 *      Extend a radix tree so it can store key @index.
 */


static int radix_tree_extend(struct radix_tree_root *root,
				unsigned long index, unsigned int shift)
{
	struct radix_tree_node *slot;
	unsigned int maxshift;
	int tag;

	/* Figure out what the shift should be.  */
	maxshift = shift;
	while (index > shift_maxindex(maxshift))
		maxshift += RADIX_TREE_MAP_SHIFT;

	slot = root->rnode;
	if (!slot)
		goto out;

	do {
		struct radix_tree_node *node = radix_tree_node_alloc(root);

		if (!node)
			return -ENOMEM;

		/* Propagate the aggregated tag info into the new root */
		for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) {
			if (root_tag_get(root, tag))
				tag_set(node, tag, 0);
		}

		BUG_ON(shift > BITS_PER_LONG);
		node->shift = shift;
		node->offset = 0;
		node->count = 1;
		node->parent = NULL;
		if (radix_tree_is_internal_node(slot))
			entry_to_node(slot)->parent = node;
		node->slots[0] = slot;
		slot = node_to_entry(node);
		rcu_assign_pointer(root->rnode, slot);
		shift += RADIX_TREE_MAP_SHIFT;
	} while (shift <= maxshift);
out:
	return maxshift + RADIX_TREE_MAP_SHIFT;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
andrew morton
andrew morton
100
47.85%
2
11.76%
matthew wilcox
matthew wilcox
58
27.75%
9
52.94%
hugh dickins
hugh dickins
27
12.92%
1
5.88%
nick piggin
nick piggin
19
9.09%
3
17.65%
johannes weiner
johannes weiner
4
1.91%
1
5.88%
jonathan corbet
jonathan corbet
1
0.48%
1
5.88%
Total
209
100.00%
17
100.00%

/**
 *      __radix_tree_create     -       create a slot in a radix tree
 *      @root:          radix tree root
 *      @index:         index key
 *      @order:         index occupies 2^order aligned slots
 *      @nodep:         returns node
 *      @slotp:         returns slot
 *
 *      Create, if necessary, and return the node and slot for an item
 *      at position @index in the radix tree @root.
 *
 *      Until there is more than one item in the tree, no nodes are
 *      allocated and @root->rnode is used as a direct slot instead of
 *      pointing to a node, in which case *@nodep will be NULL.
 *
 *      Returns -ENOMEM, or 0 for success.
 */


int __radix_tree_create(struct radix_tree_root *root, unsigned long index,
			unsigned order, struct radix_tree_node **nodep,
			void ***slotp)
{
	struct radix_tree_node *node = NULL, *child;
	void **slot = (void **)&root->rnode;
	unsigned long maxindex;
	unsigned int shift, offset = 0;
	unsigned long max = index | ((1UL << order) - 1);

	shift = radix_tree_load_root(root, &child, &maxindex);

	/* Make sure the tree is high enough.  */
	if (max > maxindex) {
		int error = radix_tree_extend(root, max, shift);
		if (error < 0)
			return error;
		shift = error;
		child = root->rnode;
		if (order == shift)
			shift += RADIX_TREE_MAP_SHIFT;
	}

	while (shift > order) {
		shift -= RADIX_TREE_MAP_SHIFT;
		if (child == NULL) {
			/* Have to add a child node.  */
			child = radix_tree_node_alloc(root);
			if (!child)
				return -ENOMEM;
			child->shift = shift;
			child->offset = offset;
			child->parent = node;
			rcu_assign_pointer(*slot, node_to_entry(child));
			if (node)
				node->count++;
		} else if (!radix_tree_is_internal_node(child))
			break;

		/* Go a level down */
		node = entry_to_node(child);
		offset = radix_tree_descend(node, &child, index);
		slot = &node->slots[offset];
	}

#ifdef CONFIG_RADIX_TREE_MULTIORDER
	/* Insert pointers to the canonical entry */
	if (order > shift) {
		unsigned i, n = 1 << (order - shift);
		offset = offset & ~(n - 1);
		slot = &node->slots[offset];
		child = node_to_entry(slot);
		for (i = 0; i < n; i++) {
			if (slot[i])
				return -EEXIST;
		}

		for (i = 1; i < n; i++) {
			rcu_assign_pointer(slot[i], child);
			node->count++;
		}
	}
#endif

	if (nodep)
		*nodep = node;
	if (slotp)
		*slotp = slot;
	return 0;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
matthew wilcox
matthew wilcox
257
65.56%
16
69.57%
andrew morton
andrew morton
88
22.45%
2
8.70%
johannes weiner
johannes weiner
30
7.65%
1
4.35%
nick piggin
nick piggin
11
2.81%
2
8.70%
hugh dickins
hugh dickins
5
1.28%
1
4.35%
christoph lameter
christoph lameter
1
0.26%
1
4.35%
Total
392
100.00%
23
100.00%

/**
 *      __radix_tree_insert    -    insert into a radix tree
 *      @root:          radix tree root
 *      @index:         index key
 *      @order:         key covers the 2^order indices around index
 *      @item:          item to insert
 *
 *      Insert an item into the radix tree at position @index.
 */


int __radix_tree_insert(struct radix_tree_root *root, unsigned long index,
			unsigned order, void *item)
{
	struct radix_tree_node *node;
	void **slot;
	int error;

	BUG_ON(radix_tree_is_internal_node(item));

	error = __radix_tree_create(root, index, order, &node, &slot);
	if (error)
		return error;
	if (*slot != NULL)
		return -EEXIST;
	rcu_assign_pointer(*slot, item);

	if (node) {
		unsigned offset = get_slot_offset(node, slot);
		node->count++;
		BUG_ON(tag_get(node, 0, offset));
		BUG_ON(tag_get(node, 1, offset));
		BUG_ON(tag_get(node, 2, offset));
	} else {
		BUG_ON(root_tags_get(root));
	}

	return 0;
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
johannes weiner
johannes weiner
69
44.23%
1
12.50%
andrew morton
andrew morton
40
25.64%
3
37.50%
matthew wilcox
matthew wilcox
28
17.95%
3
37.50%
nick piggin
nick piggin
19
12.18%
1
12.50%
Total
156
100.00%
8
100.00%


EXPORT_SYMBOL(__radix_tree_insert);

/**
 *      __radix_tree_lookup     -       lookup an item in a radix tree
 *      @root:          radix tree root
 *      @index:         index key
 *      @nodep:         returns node
 *      @slotp:         returns slot
 *
 *      Lookup and return the item at position @index in the radix
 *      tree @root.
 *
 *      Until there is more than one item in the tree, no nodes are
 *      allocated and @root->rnode is used as a direct slot instead of
 *      pointing to a node, in which case *@nodep will be NULL.
 */


void *__radix_tree_lookup(struct radix_tree_root *root, unsigned long index,
			  struct radix_tree_node **nodep, void ***slotp)
{
	struct radix_tree_node *node, *parent;
	unsigned long maxindex;
	void **slot;

 restart:
	parent = NULL;
	slot = (void **)&root->rnode;
	radix_tree_load_root(root, &node, &maxindex);
	if (index > maxindex)
		return NULL;

	while (radix_tree_is_internal_node(node)) {
		unsigned offset;

		if (node == RADIX_TREE_RETRY)
			goto restart;
		parent = entry_to_node(node);
		offset = radix_tree_descend(parent, &node, index);
		slot = parent->slots + offset;
	}

	if (nodep)
		*nodep = parent;
	if (slotp)
		*slotp = slot;
	return node;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
matthew wilcox
matthew wilcox
56
37.09%
5
35.71%
johannes weiner
johannes weiner
47
31.13%
2
14.29%
nick piggin
nick piggin
22
14.57%
3
21.43%
andrew morton
andrew morton
19
12.58%
2
14.29%
huang shijie
huang shijie
4
2.65%
1
7.14%
hans reiser
hans reiser
3
1.99%
1
7.14%
Total
151
100.00%
14
100.00%

/**
 *      radix_tree_lookup_slot    -    lookup a slot in a radix tree
 *      @root:          radix tree root
 *      @index:         index key
 *
 *      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)
{
	void **slot;

	if (!__radix_tree_lookup(root, index, NULL, &slot))
		return NULL;
	return slot;
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
huang shijie
huang shijie
22
52.38%
1
33.33%
johannes weiner
johannes weiner
18
42.86%
1
33.33%
hans reiser
hans reiser
2
4.76%
1
33.33%
Total
42
100.00%
3
100.00%


EXPORT_SYMBOL(radix_tree_lookup_slot);

/**
 *      radix_tree_lookup    -    perform lookup operation on a radix tree
 *      @root:          radix tree root
 *      @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)
{
	return __radix_tree_lookup(root, index, NULL, NULL);
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
hans reiser
hans reiser
15
55.56%
1
16.67%
nick piggin
nick piggin
4
14.81%
2
33.33%
johannes weiner
johannes weiner
4
14.81%
1
16.67%
huang shijie
huang shijie
3
11.11%
1
16.67%
andrew morton
andrew morton
1
3.70%
1
16.67%
Total
27
100.00%
6
100.00%


EXPORT_SYMBOL(radix_tree_lookup);

/**
 *      radix_tree_tag_set - set a tag on a radix tree node
 *      @root:          radix tree root
 *      @index:         index key
 *      @tag:           tag index
 *
 *      Set the search tag (which must be < RADIX_TREE_MAX_TAGS)
 *      corresponding to @index in the radix tree.  From
 *      the root all the way down to the leaf node.
 *
 *      Returns the address of the tagged item.  Setting a tag on a not-present
 *      item is a bug.
 */


void *radix_tree_tag_set(struct radix_tree_root *root,
			unsigned long index, unsigned int tag)
{
	struct radix_tree_node *node, *parent;
	unsigned long maxindex;

	radix_tree_load_root(root, &node, &maxindex);
	BUG_ON(index > maxindex);

	while (radix_tree_is_internal_node(node)) {
		unsigned offset;

		parent = entry_to_node(node);
		offset = radix_tree_descend(parent, &node, index);
		BUG_ON(!node);

		if (!tag_get(parent, tag, offset))
			tag_set(parent, tag, offset);
	}

	/* set the root's tag bit */
	if (!root_tag_get(root, tag