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linux-sg2042/lib/radix-tree.c

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/*
* 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/bitmap.h>
#include <linux/bitops.h>
#include <linux/cpu.h>
#include <linux/errno.h>
#include <linux/export.h>
#include <linux/idr.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/kmemleak.h>
#include <linux/percpu.h>
#include <linux/preempt.h> /* in_interrupt() */
#include <linux/radix-tree.h>
#include <linux/rcupdate.h>
#include <linux/slab.h>
#include <linux/string.h>
/* 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)
/*
* The IDR does not have to be as high as the radix tree since it uses
* signed integers, not unsigned longs.
*/
#define IDR_INDEX_BITS (8 /* CHAR_BIT */ * sizeof(int) - 1)
#define IDR_MAX_PATH (DIV_ROUND_UP(IDR_INDEX_BITS, \
RADIX_TREE_MAP_SHIFT))
#define IDR_PRELOAD_SIZE (IDR_MAX_PATH * 2 - 1)
/*
* The IDA is even shorter since it uses a bitmap at the last level.
*/
#define IDA_INDEX_BITS (8 * sizeof(int) - 1 - ilog2(IDA_BITMAP_BITS))
#define IDA_MAX_PATH (DIV_ROUND_UP(IDA_INDEX_BITS, \
RADIX_TREE_MAP_SHIFT))
#define IDA_PRELOAD_SIZE (IDA_MAX_PATH * 2 - 1)
/*
* Per-cpu pool of preloaded nodes
*/
struct radix_tree_preload {
unsigned nr;
/* nodes->parent points to next preallocated node */
struct radix_tree_node *nodes;
};
static DEFINE_PER_CPU(struct radix_tree_preload, radix_tree_preloads) = { 0, };
static inline struct radix_tree_node *entry_to_node(void *ptr)
{
return (void *)((unsigned long)ptr & ~RADIX_TREE_INTERNAL_NODE);
}
static inline void *node_to_entry(void *ptr)
{
return (void *)((unsigned long)ptr | RADIX_TREE_INTERNAL_NODE);
}
#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(const struct radix_tree_node *parent, void *node)
{
void __rcu **ptr = node;
return (parent->slots <= ptr) &&
(ptr < parent->slots + RADIX_TREE_MAP_SIZE);
}
#else
static inline
bool is_sibling_entry(const struct radix_tree_node *parent, void *node)
{
return false;
}
#endif
static inline unsigned long
get_slot_offset(const struct radix_tree_node *parent, void __rcu **slot)
{
return slot - parent->slots;
}
static unsigned int radix_tree_descend(const struct radix_tree_node *parent,
struct radix_tree_node **nodep, unsigned long index)
{
unsigned int offset = (index >> parent->shift) & RADIX_TREE_MAP_MASK;
void __rcu **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 __rcu **sibentry;
sibentry = (void __rcu **) entry_to_node(entry);
offset = get_slot_offset(parent, sibentry);
entry = rcu_dereference_raw(*sibentry);
}
}
#endif
*nodep = (void *)entry;
return offset;
}
static inline gfp_t root_gfp_mask(const 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(const 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 tag)
{
root->gfp_mask |= (__force gfp_t)(1 << (tag + ROOT_TAG_SHIFT));
}
static inline void root_tag_clear(struct radix_tree_root *root, unsigned tag)
{
root->gfp_mask &= (__force gfp_t)~(1 << (tag + ROOT_TAG_SHIFT));
}
static inline void root_tag_clear_all(struct radix_tree_root *root)
{
root->gfp_mask &= (1 << ROOT_TAG_SHIFT) - 1;
}
static inline int root_tag_get(const struct radix_tree_root *root, unsigned tag)
{
return (__force int)root->gfp_mask & (1 << (tag + ROOT_TAG_SHIFT));
}
static inline unsigned root_tags_get(const struct radix_tree_root *root)
{
return (__force unsigned)root->gfp_mask >> ROOT_TAG_SHIFT;
}
static inline bool is_idr(const struct radix_tree_root *root)
{
return !!(root->gfp_mask & ROOT_IS_IDR);
}
/*
* Returns 1 if any slot in the node has this tag set.
* Otherwise returns 0.
*/
static inline int any_tag_set(const 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;
}
static inline void all_tag_set(struct radix_tree_node *node, unsigned int tag)
{
bitmap_fill(node->tags[tag], RADIX_TREE_MAP_SIZE);
}
/**
* 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(struct radix_tree_node *node, unsigned int tag,
unsigned long offset)
{
const unsigned long *addr = node->tags[tag];
if (offset < RADIX_TREE_MAP_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 < RADIX_TREE_MAP_SIZE) {
tmp = *++addr;
if (tmp)
return __ffs(tmp) + offset;
offset += BITS_PER_LONG;
}
}
return RADIX_TREE_MAP_SIZE;
}
static unsigned int iter_offset(const struct radix_tree_iter *iter)
{
return (iter->index >> iter_shift(iter)) & RADIX_TREE_MAP_MASK;
}
/*
* 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;
}
static inline unsigned long node_maxindex(const struct radix_tree_node *node)
{
return shift_maxindex(node->shift);
}
static unsigned long next_index(unsigned long index,
const struct radix_tree_node *node,
unsigned long offset)
{
return (index & ~node_maxindex(node)) + (offset << node->shift);
}
#ifndef __KERNEL__
static void dump_node(struct radix_tree_node *node, unsigned long index)
{
unsigned long i;
pr_debug("radix node: %p offset %d indices %lu-%lu parent %p tags %lx %lx %lx shift %d count %d exceptional %d\n",
node, node->offset, index, index | node_maxindex(node),
node->parent,
node->tags[0][0], node->tags[1][0], node->tags[2][0],
node->shift, node->count, node->exceptional);
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 (entry == RADIX_TREE_RETRY) {
pr_debug("radix retry offset %ld indices %lu-%lu parent %p\n",
i, first, last, node);
} else if (!radix_tree_is_internal_node(entry)) {
pr_debug("radix entry %p offset %ld indices %lu-%lu parent %p\n",
entry, i, first, last, node);
} else if (is_sibling_entry(node, entry)) {
pr_debug("radix sblng %p offset %ld indices %lu-%lu parent %p val %p\n",
entry, i, first, last, node,
*(void **)entry_to_node(entry));
} else {
dump_node(entry_to_node(entry), first);
}
}
}
/* 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 >> ROOT_TAG_SHIFT);
if (!radix_tree_is_internal_node(root->rnode))
return;
dump_node(entry_to_node(root->rnode), 0);
}
static void dump_ida_node(void *entry, unsigned long index)
{
unsigned long i;
if (!entry)
return;
if (radix_tree_is_internal_node(entry)) {
struct radix_tree_node *node = entry_to_node(entry);
pr_debug("ida node: %p offset %d indices %lu-%lu parent %p free %lx shift %d count %d\n",
node, node->offset, index * IDA_BITMAP_BITS,
((index | node_maxindex(node)) + 1) *
IDA_BITMAP_BITS - 1,
node->parent, node->tags[0][0], node->shift,
node->count);
for (i = 0; i < RADIX_TREE_MAP_SIZE; i++)
dump_ida_node(node->slots[i],
index | (i << node->shift));
} else if (radix_tree_exceptional_entry(entry)) {
pr_debug("ida excp: %p offset %d indices %lu-%lu data %lx\n",
entry, (int)(index & RADIX_TREE_MAP_MASK),
index * IDA_BITMAP_BITS,
index * IDA_BITMAP_BITS + BITS_PER_LONG -
RADIX_TREE_EXCEPTIONAL_SHIFT,
(unsigned long)entry >>
RADIX_TREE_EXCEPTIONAL_SHIFT);
} else {
struct ida_bitmap *bitmap = entry;
pr_debug("ida btmp: %p offset %d indices %lu-%lu data", bitmap,
(int)(index & RADIX_TREE_MAP_MASK),
index * IDA_BITMAP_BITS,
(index + 1) * IDA_BITMAP_BITS - 1);
for (i = 0; i < IDA_BITMAP_LONGS; i++)
pr_cont(" %lx", bitmap->bitmap[i]);
pr_cont("\n");
}
}
static void ida_dump(struct ida *ida)
{
struct radix_tree_root *root = &ida->ida_rt;
pr_debug("ida: %p node %p free %d\n", ida, root->rnode,
root->gfp_mask >> ROOT_TAG_SHIFT);
dump_ida_node(root->rnode, 0);
}
#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(gfp_t gfp_mask, struct radix_tree_node *parent,
struct radix_tree_root *root,
unsigned int shift, unsigned int offset,
unsigned int count, unsigned int exceptional)
{
struct radix_tree_node *ret = NULL;
/*
* 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->parent;
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));
if (ret) {
ret->shift = shift;
ret->offset = offset;
ret->count = count;
ret->exceptional = exceptional;
ret->parent = parent;
ret->root = root;
}
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. We can be left with
* non-NULL entries by radix_tree_free_nodes, so clear the entries
* and tags here.
*/
memset(node->slots, 0, sizeof(node->slots));
memset(node->tags, 0, sizeof(node->tags));
INIT_LIST_HEAD(&node->private_list);
kmem_cache_free(radix_tree_node_cachep, node);
}
static inline void
radix_tree_node_free(struct radix_tree_node *node)
{
call_rcu(&node->rcu_head, radix_tree_node_rcu_free);
}
/*
* 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, unsigned 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->parent = rtp->nodes;
rtp->nodes = node;
rtp->nr++;
} else {
kmem_cache_free(radix_tree_node_cachep, node);
}
}
ret = 0;
out:
return ret;
}
/*
* 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);
}
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;
}
EXPORT_SYMBOL(radix_tree_maybe_preload);
#ifdef CONFIG_RADIX_TREE_MULTIORDER
/*
* Preload with enough objects to ensure that we can split a single entry
* of order @old_order into many entries of size @new_order
*/
int radix_tree_split_preload(unsigned int old_order, unsigned int new_order,
gfp_t gfp_mask)
{
unsigned top = 1 << (old_order % RADIX_TREE_MAP_SHIFT);
unsigned layers = (old_order / RADIX_TREE_MAP_SHIFT) -
(new_order / RADIX_TREE_MAP_SHIFT);
unsigned nr = 0;
WARN_ON_ONCE(!gfpflags_allow_blocking(gfp_mask));
BUG_ON(new_order >= old_order);
while (layers--)
nr = nr * RADIX_TREE_MAP_SIZE + 1;
return __radix_tree_preload(gfp_mask, top * nr);
}
#endif
/*
* 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);
}
static unsigned radix_tree_load_root(const 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;
}
/*
* Extend a radix tree so it can store key @index.
*/
static int radix_tree_extend(struct radix_tree_root *root, gfp_t gfp,
unsigned long index, unsigned int shift)
{
void *entry;
unsigned int maxshift;
int tag;
/* Figure out what the shift should be. */
maxshift = shift;
while (index > shift_maxindex(maxshift))
maxshift += RADIX_TREE_MAP_SHIFT;
entry = rcu_dereference_raw(root->rnode);
if (!entry && (!is_idr(root) || root_tag_get(root, IDR_FREE)))
goto out;
do {
struct radix_tree_node *node = radix_tree_node_alloc(gfp, NULL,
root, shift, 0, 1, 0);
if (!node)
return -ENOMEM;
if (is_idr(root)) {
all_tag_set(node, IDR_FREE);
if (!root_tag_get(root, IDR_FREE)) {
tag_clear(node, IDR_FREE, 0);
root_tag_set(root, IDR_FREE);
}
} else {
/* Propagate the aggregated tag info to the new child */
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);
if (radix_tree_is_internal_node(entry)) {
entry_to_node(entry)->parent = node;
} else if (radix_tree_exceptional_entry(entry)) {
/* Moving an exceptional root->rnode to a node */
node->exceptional = 1;
}
/*
* entry was already in the radix tree, so we do not need
* rcu_assign_pointer here
*/
node->slots[0] = (void __rcu *)entry;
entry = node_to_entry(node);
rcu_assign_pointer(root->rnode, entry);
shift += RADIX_TREE_MAP_SHIFT;
} while (shift <= maxshift);
out:
return maxshift + RADIX_TREE_MAP_SHIFT;
}
/**
* radix_tree_shrink - shrink radix tree to minimum height
* @root radix tree root
*/
static inline bool radix_tree_shrink(struct radix_tree_root *root,
radix_tree_update_node_t update_node,
void *private)
{
bool shrunk = false;
for (;;) {
struct radix_tree_node *node = rcu_dereference_raw(root->rnode);
struct radix_tree_node *child;
if (!radix_tree_is_internal_node(node))
break;
node = entry_to_node(node);
/*
* The candidate node has more than one child, or its child
* is not at the leftmost slot, or the child is a multiorder
* entry, we cannot shrink.
*/
if (node->count != 1)
break;
child = rcu_dereference_raw(node->slots[0]);
if (!child)
break;
if (!radix_tree_is_internal_node(child) && node->shift)
break;
if (radix_tree_is_internal_node(child))
entry_to_node(child)->parent = NULL;
/*
* 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
* (node->slots[0]), it will be safe to dereference the new
* one (root->rnode) as far as dependent read barriers go.
*/
root->rnode = (void __rcu *)child;
if (is_idr(root) && !tag_get(node, IDR_FREE, 0))
root_tag_clear(root, IDR_FREE);
/*
* We have a dilemma here. The node's slot[0] must not be
* NULLed in case there are concurrent lookups expecting to
* find the item. However if this was a bottom-level node,
* then it may be subject to the slot pointer being visible
* to callers dereferencing it. If item corresponding to
* slot[0] is subsequently deleted, these callers would expect
* their slot to become empty sooner or later.
*
* For example, lockless pagecache will look up a slot, deref
* the page pointer, and if the page has 0 refcount it means it
* was concurrently deleted from pagecache so try the deref
* again. Fortunately there is already a requirement for logic
* to retry the entire slot lookup -- the indirect pointer
* problem (replacing direct root node with an indirect pointer
* also results in a stale slot). So tag the slot as indirect
* to force callers to retry.
*/
node->count = 0;
if (!radix_tree_is_internal_node(child)) {
node->slots[0] = (void __rcu *)RADIX_TREE_RETRY;
if (update_node)
update_node(node, private);
}
WARN_ON_ONCE(!list_empty(&node->private_list));
radix_tree_node_free(node);
shrunk = true;
}
return shrunk;
}
static bool delete_node(struct radix_tree_root *root,
struct radix_tree_node *node,
radix_tree_update_node_t update_node, void *private)
{
bool deleted = false;
do {
struct radix_tree_node *parent;
if (node->count) {
if (node_to_entry(node) ==
rcu_dereference_raw(root->rnode))
deleted |= radix_tree_shrink(root, update_node,
private);
return deleted;
}
parent = node->parent;
if (parent) {
parent->slots[node->offset] = NULL;
parent->count--;
} else {
/*
* Shouldn't the tags already have all been cleared
* by the caller?
*/
if (!is_idr(root))
root_tag_clear_all(root);
root->rnode = NULL;
}
WARN_ON_ONCE(!list_empty(&node->private_list));
radix_tree_node_free(node);
deleted = true;
node = parent;
} while (node);
return deleted;
}
/**
* __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 __rcu ***slotp)
{
struct radix_tree_node *node = NULL, *child;
void __rcu **slot = (void __rcu **)&root->rnode;
unsigned long maxindex;
unsigned int shift, offset = 0;
unsigned long max = index | ((1UL << order) - 1);
gfp_t gfp = root_gfp_mask(root);
shift = radix_tree_load_root(root, &child, &maxindex);
/* Make sure the tree is high enough. */
if (order > 0 && max == ((1UL << order) - 1))
max++;
if (max > maxindex) {
int error = radix_tree_extend(root, gfp, max, shift);
if (error < 0)
return error;
shift = error;
child = rcu_dereference_raw(root->rnode);
}
while (shift > order) {
shift -= RADIX_TREE_MAP_SHIFT;
if (child == NULL) {
/* Have to add a child node. */
child = radix_tree_node_alloc(gfp, node, root, shift,
offset, 0, 0);
if (!child)
return -ENOMEM;
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];
}
if (nodep)
*nodep = node;
if (slotp)
*slotp = slot;
return 0;
}
/*
* Free any nodes below this node. The tree is presumed to not need
* shrinking, and any user data in the tree is presumed to not need a
* destructor called on it. If we need to add a destructor, we can
* add that functionality later. Note that we may not clear tags or
* slots from the tree as an RCU walker may still have a pointer into
* this subtree. We could replace the entries with RADIX_TREE_RETRY,
* but we'll still have to clear those in rcu_free.
*/
static void radix_tree_free_nodes(struct radix_tree_node *node)
{
unsigned offset = 0;
struct radix_tree_node *child = entry_to_node(node);
for (;;) {
void *entry = rcu_dereference_raw(child->slots[offset]);
if (radix_tree_is_internal_node(entry) &&
!is_sibling_entry(child, entry)) {
child = entry_to_node(entry);
offset = 0;
continue;
}
offset++;
while (offset == RADIX_TREE_MAP_SIZE) {
struct radix_tree_node *old = child;
offset = child->offset + 1;
child = child->parent;
WARN_ON_ONCE(!list_empty(&old->private_list));
radix_tree_node_free(old);
if (old == entry_to_node(node))
return;
}
}
}
#ifdef CONFIG_RADIX_TREE_MULTIORDER
static inline int insert_entries(struct radix_tree_node *node,
void __rcu **slot, void *item, unsigned order, bool replace)
{
struct radix_tree_node *child;
unsigned i, n, tag, offset, tags = 0;
if (node) {
if (order > node->shift)
n = 1 << (order - node->shift);
else
n = 1;
offset = get_slot_offset(node, slot);
} else {
n = 1;
offset = 0;
}
if (n > 1) {
offset = offset & ~(n - 1);
slot = &node->slots[offset];
}
child = node_to_entry(slot);
for (i = 0; i < n; i++) {
if (slot[i]) {
if (replace) {
node->count--;
for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++)
if (tag_get(node, tag, offset + i))
tags |= 1 << tag;
} else
return -EEXIST;
}
}
for (i = 0; i < n; i++) {
struct radix_tree_node *old = rcu_dereference_raw(slot[i]);
if (i) {
rcu_assign_pointer(slot[i], child);
for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++)
if (tags & (1 << tag))
tag_clear(node, tag, offset + i);
} else {
rcu_assign_pointer(slot[i], item);
for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++)
if (tags & (1 << tag))
tag_set(node, tag, offset);
}
if (radix_tree_is_internal_node(old) &&
!is_sibling_entry(node, old) &&
(old != RADIX_TREE_RETRY))
radix_tree_free_nodes(old);
if (radix_tree_exceptional_entry(old))
node->exceptional--;
}
if (node) {
node->count += n;
if (radix_tree_exceptional_entry(item))
node->exceptional += n;
}
return n;
}
#else
static inline int insert_entries(struct radix_tree_node *node,
void __rcu **slot, void *item, unsigned order, bool replace)
{
if (*slot)
return -EEXIST;
rcu_assign_pointer(*slot, item);
if (node) {
node->count++;
if (radix_tree_exceptional_entry(item))
node->exceptional++;
}
return 1;
}
#endif
/**
* __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 __rcu **slot;
int error;
BUG_ON(radix_tree_is_internal_node(item));
error = __radix_tree_create(root, index, order, &node, &slot);
if (error)
return error;
error = insert_entries(node, slot, item, order, false);
if (error < 0)
return error;
if (node) {
unsigned offset = get_slot_offset(node, slot);
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;
}
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(const struct radix_tree_root *root,
unsigned long index, struct radix_tree_node **nodep,
void __rcu ***slotp)
{
struct radix_tree_node *node, *parent;
unsigned long maxindex;
void __rcu **slot;
restart:
parent = NULL;
slot = (void __rcu **)&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;
}
/**
* 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 __rcu **radix_tree_lookup_slot(const struct radix_tree_root *root,
unsigned long index)
{
void __rcu **slot;
if (!__radix_tree_lookup(root, index, NULL, &slot))
return NULL;
return slot;
}
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(const struct radix_tree_root *root, unsigned long index)
{
return __radix_tree_lookup(root, index, NULL, NULL);
}
EXPORT_SYMBOL(radix_tree_lookup);
static inline void replace_sibling_entries(struct radix_tree_node *node,
void __rcu **slot, int count, int exceptional)
{
#ifdef CONFIG_RADIX_TREE_MULTIORDER
void *ptr = node_to_entry(slot);
unsigned offset = get_slot_offset(node, slot) + 1;
while (offset < RADIX_TREE_MAP_SIZE) {
if (rcu_dereference_raw(node->slots[offset]) != ptr)
break;
if (count < 0) {
node->slots[offset] = NULL;
node->count--;
}
node->exceptional += exceptional;
offset++;
}
#endif
}
static void replace_slot(void __rcu **slot, void *item,
struct radix_tree_node *node, int count, int exceptional)
{
if (WARN_ON_ONCE(radix_tree_is_internal_node(item)))
return;
if (node && (count || exceptional)) {
node->count += count;
node->exceptional += exceptional;
replace_sibling_entries(node, slot, count, exceptional);
}
rcu_assign_pointer(*slot, item);
}
static bool node_tag_get(const struct radix_tree_root *root,
const struct radix_tree_node *node,
unsigned int tag, unsigned int offset)
{
if (node)
return tag_get(node, tag, offset);
return root_tag_get(root, tag);
}
/*
* IDR users want to be able to store NULL in the tree, so if the slot isn't
* free, don't adjust the count, even if it's transitioning between NULL and
* non-NULL. For the IDA, we mark slots as being IDR_FREE while they still
* have empty bits, but it only stores NULL in slots when they're being
* deleted.
*/
static int calculate_count(struct radix_tree_root *root,
struct radix_tree_node *node, void __rcu **slot,
void *item, void *old)
{
if (is_idr(root)) {
unsigned offset = get_slot_offset(node, slot);
bool free = node_tag_get(root, node, IDR_FREE, offset);
if (!free)
return 0;
if (!old)
return 1;
}
return !!item - !!old;
}
/**
* __radix_tree_replace - replace item in a slot
* @root: radix tree root
* @node: pointer to tree node
* @slot: pointer to slot in @node
* @item: new item to store in the slot.
* @update_node: callback for changing leaf nodes
* @private: private data to pass to @update_node
*
* For use with __radix_tree_lookup(). Caller must hold tree write locked
* across slot lookup and replacement.
*/
void __radix_tree_replace(struct radix_tree_root *root,
struct radix_tree_node *node,
void __rcu **slot, void *item,
radix_tree_update_node_t update_node, void *private)
{
void *old = rcu_dereference_raw(*slot);
int exceptional = !!radix_tree_exceptional_entry(item) -
!!radix_tree_exceptional_entry(old);
int count = calculate_count(root, node, slot, item, old);
/*
* This function supports replacing exceptional entries and
* deleting entries, but that needs accounting against the
* node unless the slot is root->rnode.
*/
WARN_ON_ONCE(!node && (slot != (void __rcu **)&root->rnode) &&
(count || exceptional));
replace_slot(slot, item, node, count, exceptional);
if (!node)
return;
if (update_node)
update_node(node, private);
delete_node(root, node, update_node, private);
}
/**
* radix_tree_replace_slot - replace item in a slot
* @root: radix tree root
* @slot: pointer to slot
* @item: new item to store in the slot.
*
* For use with radix_tree_lookup_slot(), radix_tree_gang_lookup_slot(),
* radix_tree_gang_lookup_tag_slot(). Caller must hold tree write locked
* across slot lookup and replacement.
*
* NOTE: This cannot be used to switch between non-entries (empty slots),
* regular entries, and exceptional entries, as that requires accounting
* inside the radix tree node. When switching from one type of entry or
* deleting, use __radix_tree_lookup() and __radix_tree_replace() or
* radix_tree_iter_replace().
*/
void radix_tree_replace_slot(struct radix_tree_root *root,
void __rcu **slot, void *item)
{
__radix_tree_replace(root, NULL, slot, item, NULL, NULL);
}
EXPORT_SYMBOL(radix_tree_replace_slot);
/**
* radix_tree_iter_replace - replace item in a slot
* @root: radix tree root
* @slot: pointer to slot
* @item: new item to store in the slot.
*
* For use with radix_tree_split() and radix_tree_for_each_slot().
* Caller must hold tree write locked across split and replacement.
*/
void radix_tree_iter_replace(struct radix_tree_root *root,
const struct radix_tree_iter *iter,
void __rcu **slot, void *item)
{
__radix_tree_replace(root, iter->node, slot, item, NULL, NULL);
}
#ifdef CONFIG_RADIX_TREE_MULTIORDER
/**
* radix_tree_join - replace multiple entries with one multiorder entry
* @root: radix tree root
* @index: an index inside the new entry
* @order: order of the new entry
* @item: new entry
*
* Call this function to replace several entries with one larger entry.
* The existing entries are presumed to not need freeing as a result of
* this call.
*
* The replacement entry will have all the tags set on it that were set
* on any of the entries it is replacing.
*/
int radix_tree_join(struct radix_tree_root *root, unsigned long index,
unsigned order, void *item)
{
struct radix_tree_node *node;
void __rcu **slot;
int error;
BUG_ON(radix_tree_is_internal_node(item));
error = __radix_tree_create(root, index, order, &node, &slot);
if (!error)
error = insert_entries(node, slot, item, order, true);
if (error > 0)
error = 0;
return error;
}
/**
* radix_tree_split - Split an entry into smaller entries
* @root: radix tree root
* @index: An index within the large entry
* @order: Order of new entries
*
* Call this function as the first step in replacing a multiorder entry
* with several entries of lower order. After this function returns,
* loop over the relevant portion of the tree using radix_tree_for_each_slot()
* and call radix_tree_iter_replace() to set up each new entry.
*
* The tags from this entry are replicated to all the new entries.
*
* The radix tree should be locked against modification during the entire
* replacement operation. Lock-free lookups will see RADIX_TREE_RETRY which
* should prompt RCU walkers to restart the lookup from the root.
*/
int radix_tree_split(struct radix_tree_root *root, unsigned long index,
unsigned order)
{
struct radix_tree_node *parent, *node, *child;
void __rcu **slot;
unsigned int offset, end;
unsigned n, tag, tags = 0;
gfp_t gfp = root_gfp_mask(root);
if (!__radix_tree_lookup(root, index, &parent, &slot))
return -ENOENT;
if (!parent)
return -ENOENT;
offset = get_slot_offset(parent, slot);
for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++)
if (tag_get(parent, tag, offset))
tags |= 1 << tag;
for (end = offset + 1; end < RADIX_TREE_MAP_SIZE; end++) {
if (!is_sibling_entry(parent,
rcu_dereference_raw(parent->slots[end])))
break;
for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++)
if (tags & (1 << tag))
tag_set(parent, tag, end);
/* rcu_assign_pointer ensures tags are set before RETRY */
rcu_assign_pointer(parent->slots[end], RADIX_TREE_RETRY);
}
rcu_assign_pointer(parent->slots[offset], RADIX_TREE_RETRY);
parent->exceptional -= (end - offset);
if (order == parent->shift)
return 0;
if (order > parent->shift) {
while (offset < end)
offset += insert_entries(parent, &parent->slots[offset],
RADIX_TREE_RETRY, order, true);
return 0;
}
node = parent;
for (;;) {
if (node->shift > order) {
child = radix_tree_node_alloc(gfp, node, root,
node->shift - RADIX_TREE_MAP_SHIFT,
offset, 0, 0);
if (!child)
goto nomem;
if (node != parent) {
node->count++;
rcu_assign_pointer(node->slots[offset],
node_to_entry(child));
for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++)
if (tags & (1 << tag))
tag_set(node, tag, offset);
}
node = child;
offset = 0;
continue;
}
n = insert_entries(node, &node->slots[offset],
RADIX_TREE_RETRY, order, false);
BUG_ON(n > RADIX_TREE_MAP_SIZE);
for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++)
if (tags & (1 << tag))
tag_set(node, tag, offset);
offset += n;
while (offset == RADIX_TREE_MAP_SIZE) {
if (node == parent)
break;
offset = node->offset;
child = node;
node = node->parent;
rcu_assign_pointer(node->slots[offset],
node_to_entry(child));
offset++;
}
if ((node == parent) && (offset == end))
return 0;
}
nomem:
/* Shouldn't happen; did user forget to preload? */
/* TODO: free all the allocated nodes */
WARN_ON(1);
return -ENOMEM;
}
#endif
static void node_tag_set(struct radix_tree_root *root,
struct radix_tree_node *node,
unsigned int tag, unsigned int offset)
{
while (node) {
if (tag_get(node, tag, offset))
return;
tag_set(node, tag, offset);
offset = node->offset;
node = node->parent;
}
if (!root_tag_get(root, tag))
root_tag_set(root, tag);
}
/**
* 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))
root_tag_set(root, tag);
return node;
}
EXPORT_SYMBOL(radix_tree_tag_set);
/**
* radix_tree_iter_tag_set - set a tag on the current iterator entry
* @root: radix tree root
* @iter: iterator state
* @tag: tag to set
*/
void radix_tree_iter_tag_set(struct radix_tree_root *root,
const struct radix_tree_iter *iter, unsigned int tag)
{
node_tag_set(root, iter->node, tag, iter_offset(iter));
}
static void node_tag_clear(struct radix_tree_root *root,
struct radix_tree_node *node,
unsigned int tag, unsigned int offset)
{
while (node) {
if (!tag_get(node, tag, offset))
return;
tag_clear(node, tag, offset);
if (any_tag_set(node, tag))
return;
offset = node->offset;
node = node->parent;
}
/* clear the root's tag bit */
if (root_tag_get(root, tag))
root_tag_clear(root, tag);
}
/**
* radix_tree_tag_clear - clear a tag on a radix tree node
* @root: radix tree root
* @index: index key
* @tag: tag index
*
* Clear the search tag (which must be < RADIX_TREE_MAX_TAGS)
* corresponding to @index in the radix tree. If this causes
* the leaf node to have no tags set then clear the tag in the
* next-to-leaf node, etc.
*
* Returns the address of the tagged item on success, else NULL. ie:
* has the same return value and semantics as radix_tree_lookup().
*/
void *radix_tree_tag_clear(struct radix_tree_root *root,
unsigned long index, unsigned int tag)
{
struct radix_tree_node *node, *parent;
unsigned long maxindex;
int uninitialized_var(offset);
radix_tree_load_root(root, &node, &maxindex);
if (index > maxindex)
return NULL;
parent = NULL;
while (radix_tree_is_internal_node(node)) {
parent = entry_to_node(node);
offset = radix_tree_descend(parent, &node, index);
}
if (node)
node_tag_clear(root, parent, tag, offset);
return node;
}
EXPORT_SYMBOL(radix_tree_tag_clear);
/**
* radix_tree_iter_tag_clear - clear a tag on the current iterator entry
* @root: radix tree root
* @iter: iterator state
* @tag: tag to clear
*/
void radix_tree_iter_tag_clear(struct radix_tree_root *root,
const struct radix_tree_iter *iter, unsigned int tag)
{
node_tag_clear(root, iter->node, tag, iter_offset(iter));
}
/**
* radix_tree_tag_get - get a tag on a radix tree node
* @root: radix tree root
* @index: index key
* @tag: tag index (< RADIX_TREE_MAX_TAGS)
*
* Return values:
*
* 0: tag not present or not set
* 1: tag set
*
* Note that the return value of this function may not be relied on, even if
* the RCU lock is held, unless tag modification and node deletion are excluded
* from concurrency.
*/
int radix_tree_tag_get(const struct radix_tree_root *root,
unsigned long index, unsigned int tag)
{
struct radix_tree_node *node, *parent;
unsigned long maxindex;
if (!root_tag_get(root, tag))
return 0;
radix_tree_load_root(root, &node, &maxindex);
if (index > maxindex)
return 0;
while (radix_tree_is_internal_node(node)) {
unsigned offset;
parent = entry_to_node(node);
offset = radix_tree_descend(parent, &node, index);
if (!tag_get(parent, tag, offset))
return 0;
if (node == RADIX_TREE_RETRY)
break;
}
return 1;
}
EXPORT_SYMBOL(radix_tree_tag_get);
static inline void __set_iter_shift(struct radix_tree_iter *iter,
unsigned int shift)
{
#ifdef CONFIG_RADIX_TREE_MULTIORDER
iter->shift = shift;
#endif
}
/* Construct iter->tags bit-mask from node->tags[tag] array */
static void set_iter_tags(struct radix_tree_iter *iter,
struct radix_tree_node *node, unsigned offset,
unsigned tag)
{
unsigned tag_long = offset / BITS_PER_LONG;
unsigned tag_bit = offset % BITS_PER_LONG;
if (!node) {
iter->tags = 1;
return;
}
iter->tags = node->tags[tag][tag_long] >> tag_bit;
/* This never happens if RADIX_TREE_TAG_LONGS == 1 */
if (tag_long < RADIX_TREE_TAG_LONGS - 1) {
/* Pick tags from next element */
if (tag_bit)
iter->tags |= node->tags[tag][tag_long + 1] <<
(BITS_PER_LONG - tag_bit);
/* Clip chunk size, here only BITS_PER_LONG tags */
iter->next_index = __radix_tree_iter_add(iter, BITS_PER_LONG);
}
}
#ifdef CONFIG_RADIX_TREE_MULTIORDER
static void __rcu **skip_siblings(struct radix_tree_node **nodep,
void __rcu **slot, struct radix_tree_iter *iter)
{
void *sib = node_to_entry(slot - 1);
while (iter->index < iter->next_index) {
*nodep = rcu_dereference_raw(*slot);
if (*nodep && *nodep != sib)
return slot;
slot++;
iter->index = __radix_tree_iter_add(iter, 1);
iter->tags >>= 1;
}
*nodep = NULL;
return NULL;
}
void __rcu **__radix_tree_next_slot(void __rcu **slot,
struct radix_tree_iter *iter, unsigned flags)
{
unsigned tag = flags & RADIX_TREE_ITER_TAG_MASK;
struct radix_tree_node *node = rcu_dereference_raw(*slot);
slot = skip_siblings(&node, slot, iter);
while (radix_tree_is_internal_node(node)) {
unsigned offset;
unsigned long next_index;
if (node == RADIX_TREE_RETRY)
return slot;
node = entry_to_node(node);
iter->node = node;
iter->shift = node->shift;
if (flags & RADIX_TREE_ITER_TAGGED) {
offset = radix_tree_find_next_bit(node, tag, 0);
if (offset == RADIX_TREE_MAP_SIZE)
return NULL;
slot = &node->slots[offset];
iter->index = __radix_tree_iter_add(iter, offset);
set_iter_tags(iter, node, offset, tag);
node = rcu_dereference_raw(*slot);
} else {
offset = 0;
slot = &node->slots[0];
for (;;) {
node = rcu_dereference_raw(*slot);
if (node)
break;
slot++;
offset++;
if (offset == RADIX_TREE_MAP_SIZE)
return NULL;
}
iter->index = __radix_tree_iter_add(iter, offset);
}
if ((flags & RADIX_TREE_ITER_CONTIG) && (offset > 0))
goto none;
next_index = (iter->index | shift_maxindex(iter->shift)) + 1;
if (next_index < iter->next_index)
iter->next_index = next_index;
}
return slot;
none:
iter->next_index = 0;
return NULL;
}
EXPORT_SYMBOL(__radix_tree_next_slot);
#else
static void __rcu **skip_siblings(struct radix_tree_node **nodep,
void __rcu **slot, struct radix_tree_iter *iter)
{
return slot;
}
#endif
void __rcu **radix_tree_iter_resume(void __rcu **slot,
struct radix_tree_iter *iter)
{
struct radix_tree_node *node;
slot++;
iter->index = __radix_tree_iter_add(iter, 1);
skip_siblings(&node, slot, iter);
iter->next_index = iter->index;
iter->tags = 0;
return NULL;
}
EXPORT_SYMBOL(radix_tree_iter_resume);
/**
* radix_tree_next_chunk - find next chunk of slots for iteration
*
* @root: radix tree root
* @iter: iterator state
* @flags: RADIX_TREE_ITER_* flags and tag index
* Returns: pointer to chunk first slot, or NULL if iteration is over
*/
void __rcu **radix_tree_next_chunk(const struct radix_tree_root *root,
struct radix_tree_iter *iter, unsigned flags)
{
unsigned tag = flags & RADIX_TREE_ITER_TAG_MASK;
struct radix_tree_node *node, *child;
unsigned long index, offset, maxindex;
if ((flags & RADIX_TREE_ITER_TAGGED) && !root_tag_get(root, tag))
return NULL;
/*
* Catch next_index overflow after ~0UL. iter->index never overflows
* during iterating; it can be zero only at the beginning.
* And we cannot overflow iter->next_index in a single step,
* because RADIX_TREE_MAP_SHIFT < BITS_PER_LONG.
*
* This condition also used by radix_tree_next_slot() to stop
* contiguous iterating, and forbid switching to the next chunk.
*/
index = iter->next_index;
if (!index && iter->index)
return NULL;
restart:
radix_tree_load_root(root, &child, &maxindex);
if (index > maxindex)
return NULL;
if (!child)
return NULL;
if (!radix_tree_is_internal_node(child)) {
/* Single-slot tree */
iter->index = index;
iter->next_index = maxindex + 1;
iter->tags = 1;
iter->node = NULL;
__set_iter_shift(iter, 0);
return (void __rcu **)&root->rnode;
}
do {
node = entry_to_node(child);
offset = radix_tree_descend(node, &child, index);
if ((flags & RADIX_TREE_ITER_TAGGED) ?
!tag_get(node, tag, offset) : !child) {
/* Hole detected */
if (flags & RADIX_TREE_ITER_CONTIG)
return NULL;
if (flags & RADIX_TREE_ITER_TAGGED)
offset = radix_tree_find_next_bit(node, tag,
offset + 1);
else
while (++offset < RADIX_TREE_MAP_SIZE) {
void *slot = rcu_dereference_raw(
node->slots[offset]);
if (is_sibling_entry(node, slot))
continue;
if (slot)
break;
}
index &= ~node_maxindex(node);
index += offset << node->shift;
/* Overflow after ~0UL */
if (!index)
return NULL;
if (offset == RADIX_TREE_MAP_SIZE)
goto restart;
child = rcu_dereference_raw(node->slots[offset]);
}
if (!child)
goto restart;
if (child == RADIX_TREE_RETRY)
break;
} while (radix_tree_is_internal_node(child));
/* Update the iterator state */
iter->index = (index &~ node_maxindex(node)) | (offset << node->shift);
iter->next_index = (index | node_maxindex(node)) + 1;
iter->node = node;
__set_iter_shift(iter, node->shift);
if (flags & RADIX_TREE_ITER_TAGGED)
set_iter_tags(iter, node, offset, tag);
return node->slots + offset;
}
EXPORT_SYMBOL(radix_tree_next_chunk);
/**
* radix_tree_gang_lookup - perform multiple lookup on a 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
* them at *@results and returns the number of items which were placed at
* *@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(const struct radix_tree_root *root, void **results,
unsigned long first_index, unsigned int max_items)
{
struct radix_tree_iter iter;
void __rcu **slot;
unsigned int ret = 0;
if (unlikely(!max_items))
return 0;
radix_tree_for_each_slot(slot, root, &iter, first_index) {
results[ret] = rcu_dereference_raw(*slot);
if (!results[ret])
continue;
if (radix_tree_is_internal_node(results[ret])) {
slot = radix_tree_iter_retry(&iter);
continue;
}
if (++ret == max_items)
break;
}
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
* @indices: where their indices should be placed (but usually NULL)
* @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(const struct radix_tree_root *root,
void __rcu ***results, unsigned long *indices,
unsigned long first_index, unsigned int max_items)
{
struct radix_tree_iter iter;
void __rcu **slot;
unsigned int ret = 0;
if (unlikely(!max_items))
return 0;
radix_tree_for_each_slot(slot, root, &iter, first_index) {
results[ret] = slot;
if (indices)
indices[ret] = iter.index;
if (++ret == max_items)
break;
}
return ret;
}
EXPORT_SYMBOL(radix_tree_gang_lookup_slot);
/**
* radix_tree_gang_lookup_tag - perform multiple 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 items at *@results and
* returns the number of items which were placed at *@results.
*/
unsigned int
radix_tree_gang_lookup_tag(const struct radix_tree_root *root, void **results,
unsigned long first_index, unsigned int max_items,
unsigned int tag)
{
struct radix_tree_iter iter;
void __rcu **slot;
unsigned int ret = 0;
if (unlikely(!max_items))
return 0;
radix_tree_for_each_tagged(slot, root, &iter, first_index, tag) {
results[ret] = rcu_dereference_raw(*slot);
if (!results[ret])
continue;
if (radix_tree_is_internal_node(results[ret])) {
slot = radix_tree_iter_retry(&iter);
continue;
}
if (++ret == max_items)
break;
}
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(const struct radix_tree_root *root,
void __rcu ***results, unsigned long first_index,
unsigned int max_items, unsigned int tag)
{
struct radix_tree_iter iter;
void __rcu **slot;
unsigned int ret = 0;
if (unlikely(!max_items))
return 0;
radix_tree_for_each_tagged(slot, root, &iter, first_index, tag) {
results[ret] = slot;
if (++ret == max_items)
break;
}
return ret;
}
EXPORT_SYMBOL(radix_tree_gang_lookup_tag_slot);
/**
* __radix_tree_delete_node - try to free node after clearing a slot
* @root: radix tree root
* @node: node containing @index
* @update_node: callback for changing leaf nodes
* @private: private data to pass to @update_node
*
* After clearing the slot at @index in @node from radix tree
* rooted at @root, call this function to attempt freeing the
* node and shrinking the tree.
*/
void __radix_tree_delete_node(struct radix_tree_root *root,
struct radix_tree_node *node,
radix_tree_update_node_t update_node,
void *private)
{
delete_node(root, node, update_node, private);
}
static bool __radix_tree_delete(struct radix_tree_root *root,
struct radix_tree_node *node, void __rcu **slot)
{
void *old = rcu_dereference_raw(*slot);
int exceptional = radix_tree_exceptional_entry(old) ? -1 : 0;
unsigned offset = get_slot_offset(node, slot);
int tag;
if (is_idr(root))
node_tag_set(root, node, IDR_FREE, offset);
else
for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++)
node_tag_clear(root, node, tag, offset);
replace_slot(slot, NULL, node, -1, exceptional);
return node && delete_node(root, node, NULL, NULL);
}
/**
* radix_tree_iter_delete - delete the entry at this iterator position
* @root: radix tree root
* @iter: iterator state
* @slot: pointer to slot
*
* Delete the entry at the position currently pointed to by the iterator.
* This may result in the current node being freed; if it is, the iterator
* is advanced so that it will not reference the freed memory. This
* function may be called without any locking if there are no other threads
* which can access this tree.
*/
void radix_tree_iter_delete(struct radix_tree_root *root,
struct radix_tree_iter *iter, void __rcu **slot)
{
if (__radix_tree_delete(root, iter->node, slot))
iter->index = iter->next_index;
}
EXPORT_SYMBOL(radix_tree_iter_delete);
/**
* radix_tree_delete_item - delete an item from a radix tree
* @root: radix tree root
* @index: index key
* @item: expected item
*
* Remove @item at @index from the radix tree rooted at @root.
*
* Return: the deleted entry, or %NULL if it was not present
* or the entry at the given @index was not @item.
*/
void *radix_tree_delete_item(struct radix_tree_root *root,
unsigned long index, void *item)
{
struct radix_tree_node *node = NULL;
void __rcu **slot;
void *entry;
entry = __radix_tree_lookup(root, index, &node, &slot);
if (!entry && (!is_idr(root) || node_tag_get(root, node, IDR_FREE,
get_slot_offset(node, slot))))
return NULL;
if (item && entry != item)
return NULL;
__radix_tree_delete(root, node, slot);
return entry;
}
EXPORT_SYMBOL(radix_tree_delete_item);
/**
* radix_tree_delete - delete an entry from a radix tree
* @root: radix tree root
* @index: index key
*
* Remove the entry at @index from the radix tree rooted at @root.
*
* Return: The deleted entry, or %NULL if it was not present.
*/
void *radix_tree_delete(struct radix_tree_root *root, unsigned long index)
{
return radix_tree_delete_item(root, index, NULL);
}
EXPORT_SYMBOL(radix_tree_delete);
void radix_tree_clear_tags(struct radix_tree_root *root,
struct radix_tree_node *node,
void __rcu **slot)
{
if (node) {
unsigned int tag, offset = get_slot_offset(node, slot);
for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++)
node_tag_clear(root, node, tag, offset);
} else {
root_tag_clear_all(root);
}
}
/**
* radix_tree_tagged - test whether any items in the tree are tagged
* @root: radix tree root
* @tag: tag to test
*/
int radix_tree_tagged(const struct radix_tree_root *root, unsigned int tag)
{
return root_tag_get(root, tag);
}
EXPORT_SYMBOL(radix_tree_tagged);
/**
* idr_preload - preload for idr_alloc()
* @gfp_mask: allocation mask to use for preloading
*
* Preallocate memory to use for the next call to idr_alloc(). This function
* returns with preemption disabled. It will be enabled by idr_preload_end().
*/
void idr_preload(gfp_t gfp_mask)
{
__radix_tree_preload(gfp_mask, IDR_PRELOAD_SIZE);
}
EXPORT_SYMBOL(idr_preload);
/**
* ida_pre_get - reserve resources for ida allocation
* @ida: ida handle
* @gfp: memory allocation flags
*
* This function should be called before calling ida_get_new_above(). If it
* is unable to allocate memory, it will return %0. On success, it returns %1.
*/
int ida_pre_get(struct ida *ida, gfp_t gfp)
{
__radix_tree_preload(gfp, IDA_PRELOAD_SIZE);
/*
* The IDA API has no preload_end() equivalent. Instead,
* ida_get_new() can return -EAGAIN, prompting the caller
* to return to the ida_pre_get() step.
*/
preempt_enable();
if (!this_cpu_read(ida_bitmap)) {
struct ida_bitmap *bitmap = kmalloc(sizeof(*bitmap), gfp);
if (!bitmap)
return 0;
if (this_cpu_cmpxchg(ida_bitmap, NULL, bitmap))
kfree(bitmap);
}
return 1;
}
EXPORT_SYMBOL(ida_pre_get);
void __rcu **idr_get_free_cmn(struct radix_tree_root *root,
struct radix_tree_iter *iter, gfp_t gfp,
unsigned long max)
{
struct radix_tree_node *node = NULL, *child;
void __rcu **slot = (void __rcu **)&root->rnode;
unsigned long maxindex, start = iter->next_index;
unsigned int shift, offset = 0;
grow:
shift = radix_tree_load_root(root, &child, &maxindex);
if (!radix_tree_tagged(root, IDR_FREE))
start = max(start, maxindex + 1);
if (start > max)
return ERR_PTR(-ENOSPC);
if (start > maxindex) {
int error = radix_tree_extend(root, gfp, start, shift);
if (error < 0)
return ERR_PTR(error);
shift = error;
child = rcu_dereference_raw(root->rnode);
}
while (shift) {
shift -= RADIX_TREE_MAP_SHIFT;
if (child == NULL) {
/* Have to add a child node. */
child = radix_tree_node_alloc(gfp, node, root, shift,
offset, 0, 0);
if (!child)
return ERR_PTR(-ENOMEM);
all_tag_set(child, IDR_FREE);
rcu_assign_pointer(*slot, node_to_entry(child));
if (node)
node->count++;
} else if (!radix_tree_is_internal_node(child))
break;
node = entry_to_node(child);
offset = radix_tree_descend(node, &child, start);
if (!tag_get(node, IDR_FREE, offset)) {
offset = radix_tree_find_next_bit(node, IDR_FREE,
offset + 1);
start = next_index(start, node, offset);
if (start > max)
return ERR_PTR(-ENOSPC);
while (offset == RADIX_TREE_MAP_SIZE) {
offset = node->offset + 1;
node = node->parent;
if (!node)
goto grow;
shift = node->shift;
}
child = rcu_dereference_raw(node->slots[offset]);
}
slot = &node->slots[offset];
}
iter->index = start;
if (node)
iter->next_index = 1 + min(max, (start | node_maxindex(node)));
else
iter->next_index = 1;
iter->node = node;
__set_iter_shift(iter, shift);
set_iter_tags(iter, node, offset, IDR_FREE);
return slot;
}
/**
* idr_destroy - release all internal memory from an IDR
* @idr: idr handle
*
* After this function is called, the IDR is empty, and may be reused or
* the data structure containing it may be freed.
*
* A typical clean-up sequence for objects stored in an idr tree will use
* idr_for_each() to free all objects, if necessary, then idr_destroy() to
* free the memory used to keep track of those objects.
*/
void idr_destroy(struct idr *idr)
{
struct radix_tree_node *node = rcu_dereference_raw(idr->idr_rt.rnode);
if (radix_tree_is_internal_node(node))
radix_tree_free_nodes(node);
idr->idr_rt.rnode = NULL;
root_tag_set(&idr->idr_rt, IDR_FREE);
}
EXPORT_SYMBOL(idr_destroy);
static void
radix_tree_node_ctor(void *arg)
{
struct radix_tree_node *node = arg;
memset(node, 0, sizeof(*node));
INIT_LIST_HEAD(&node->private_list);
}
static __init unsigned long __maxindex(unsigned int height)
{
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_maxnodes(void)
{
unsigned long height_to_maxindex[RADIX_TREE_MAX_PATH + 1];
unsigned int i, j;
for (i = 0; i < ARRAY_SIZE(height_to_maxindex); i++)
height_to_maxindex[i] = __maxindex(i);
for (i = 0; i < ARRAY_SIZE(height_to_maxnodes); i++) {
for (j = i; j > 0; j--)
height_to_maxnodes[i] += height_to_maxindex[j - 1] + 1;
}
}
static int radix_tree_cpu_dead(unsigned int cpu)
{
struct radix_tree_preload *rtp;
struct radix_tree_node *node;
/* Free per-cpu pool of preloaded nodes */
rtp = &per_cpu(radix_tree_preloads, cpu);
while (rtp->nr) {
node = rtp->nodes;
rtp->nodes = node->parent;
kmem_cache_free(radix_tree_node_cachep, node);
rtp->nr--;
}
kfree(per_cpu(ida_bitmap, cpu));
per_cpu(ida_bitmap, cpu) = NULL;
return 0;
}
void __init radix_tree_init(void)
{
int ret;
BUILD_BUG_ON(RADIX_TREE_MAX_TAGS + __GFP_BITS_SHIFT > 32);
radix_tree_node_cachep = kmem_cache_create("radix_tree_node",
sizeof(struct radix_tree_node), 0,
SLAB_PANIC | SLAB_RECLAIM_ACCOUNT,
radix_tree_node_ctor);
radix_tree_init_maxnodes();
ret = cpuhp_setup_state_nocalls(CPUHP_RADIX_DEAD, "lib/radix:dead",
NULL, radix_tree_cpu_dead);
WARN_ON(ret < 0);
}
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