#ifndef _LINUX_GENERIC_RADIX_TREE_H
#define _LINUX_GENERIC_RADIX_TREE_H
/**
* DOC: Generic radix trees/sparse arrays
*
* Very simple and minimalistic, supporting arbitrary size entries up to
* GENRADIX_NODE_SIZE.
*
* A genradix is defined with the type it will store, like so:
*
* static GENRADIX(struct foo) foo_genradix;
*
* The main operations are:
*
* - genradix_init(radix) - initialize an empty genradix
*
* - genradix_free(radix) - free all memory owned by the genradix and
* reinitialize it
*
* - genradix_ptr(radix, idx) - gets a pointer to the entry at idx, returning
* NULL if that entry does not exist
*
* - genradix_ptr_alloc(radix, idx, gfp) - gets a pointer to an entry,
* allocating it if necessary
*
* - genradix_for_each(radix, iter, p) - iterate over each entry in a genradix
*
* The radix tree allocates one page of entries at a time, so entries may exist
* that were never explicitly allocated - they will be initialized to all
* zeroes.
*
* Internally, a genradix is just a radix tree of pages, and indexing works in
* terms of byte offsets. The wrappers in this header file use sizeof on the
* type the radix contains to calculate a byte offset from the index - see
* __idx_to_offset.
*/
#include <asm/page.h>
#include <linux/bug.h>
#include <linux/limits.h>
#include <linux/log2.h>
#include <linux/math.h>
#include <linux/slab.h>
#include <linux/types.h>
struct genradix_root;
#define GENRADIX_NODE_SHIFT 9
#define GENRADIX_NODE_SIZE (1U << GENRADIX_NODE_SHIFT)
#define GENRADIX_ARY (GENRADIX_NODE_SIZE / sizeof(struct genradix_node *))
#define GENRADIX_ARY_SHIFT ilog2(GENRADIX_ARY)
/* depth that's needed for a genradix that can address up to ULONG_MAX: */
#define GENRADIX_MAX_DEPTH \
DIV_ROUND_UP(BITS_PER_LONG - GENRADIX_NODE_SHIFT, GENRADIX_ARY_SHIFT)
#define GENRADIX_DEPTH_MASK \
((unsigned long) (roundup_pow_of_two(GENRADIX_MAX_DEPTH + 1) - 1))
static inline int genradix_depth_shift(unsigned depth)
{
return GENRADIX_NODE_SHIFT + GENRADIX_ARY_SHIFT * depth;
}
/*
* Returns size (of data, in bytes) that a tree of a given depth holds:
*/
static inline size_t genradix_depth_size(unsigned depth)
{
return 1UL << genradix_depth_shift(depth);
}
static inline unsigned genradix_root_to_depth(struct genradix_root *r)
{
return (unsigned long) r & GENRADIX_DEPTH_MASK;
}
static inline struct genradix_node *genradix_root_to_node(struct genradix_root *r)
{
return (void *) ((unsigned long) r & ~GENRADIX_DEPTH_MASK);
}
struct __genradix {
struct genradix_root *root;
};
struct genradix_node {
union {
/* Interior node: */
struct genradix_node *children[GENRADIX_ARY];
/* Leaf: */
u8 data[GENRADIX_NODE_SIZE];
};
};
static inline struct genradix_node *genradix_alloc_node(gfp_t gfp_mask)
{
return kzalloc(GENRADIX_NODE_SIZE, gfp_mask);
}
static inline void genradix_free_node(struct genradix_node *node)
{
kfree(node);
}
/*
* NOTE: currently, sizeof(_type) must not be larger than GENRADIX_NODE_SIZE:
*/
#define __GENRADIX_INITIALIZER \
{ \
.tree = { \
.root = NULL, \
} \
}
/*
* We use a 0 size array to stash the type we're storing without taking any
* space at runtime - then the various accessor macros can use typeof() to get
* to it for casts/sizeof - we also force the alignment so that storing a type
* with a ridiculous alignment doesn't blow up the alignment or size of the
* genradix.
*/
#define GENRADIX(_type) \
struct { \
struct __genradix tree; \
_type type[0] __aligned(1); \
}
#define DEFINE_GENRADIX(_name, _type) \
GENRADIX(_type) _name = __GENRADIX_INITIALIZER
/**
* genradix_init - initialize a genradix
* @_radix: genradix to initialize
*
* Does not fail
*/
#define genradix_init(_radix) \
do { \
*(_radix) = (typeof(*_radix)) __GENRADIX_INITIALIZER; \
} while (0)
void __genradix_free(struct __genradix *);
/**
* genradix_free: free all memory owned by a genradix
* @_radix: the genradix to free
*
* After freeing, @_radix will be reinitialized and empty
*/
#define genradix_free(_radix) __genradix_free(&(_radix)->tree)
static inline size_t __idx_to_offset(size_t idx, size_t obj_size)
{
if (__builtin_constant_p(obj_size))
BUILD_BUG_ON(obj_size > GENRADIX_NODE_SIZE);
else
BUG_ON(obj_size > GENRADIX_NODE_SIZE);
if (!is_power_of_2(obj_size)) {
size_t objs_per_page = GENRADIX_NODE_SIZE / obj_size;
return (idx / objs_per_page) * GENRADIX_NODE_SIZE +
(idx % objs_per_page) * obj_size;
} else {
return idx * obj_size;
}
}
#define __genradix_cast(_radix) (typeof((_radix)->type[0]) *)
#define __genradix_obj_size(_radix) sizeof((_radix)->type[0])
#define __genradix_objs_per_page(_radix) \
(GENRADIX_NODE_SIZE / sizeof((_radix)->type[0]))
#define __genradix_page_remainder(_radix) \
(GENRADIX_NODE_SIZE % sizeof((_radix)->type[0]))
#define __genradix_idx_to_offset(_radix, _idx) \
__idx_to_offset(_idx, __genradix_obj_size(_radix))
static inline void *__genradix_ptr_inlined(struct __genradix *radix, size_t offset)
{
struct genradix_root *r = READ_ONCE(radix->root);
struct genradix_node *n = genradix_root_to_node(r);
unsigned level = genradix_root_to_depth(r);
unsigned shift = genradix_depth_shift(level);
if (unlikely(ilog2(offset) >= genradix_depth_shift(level)))
return NULL;
while (n && shift > GENRADIX_NODE_SHIFT) {
shift -= GENRADIX_ARY_SHIFT;
n = n->children[offset >> shift];
offset &= (1UL << shift) - 1;
}
return n ? &n->data[offset] : NULL;
}
#define genradix_ptr_inlined(_radix, _idx) \
(__genradix_cast(_radix) \
__genradix_ptr_inlined(&(_radix)->tree, \
__genradix_idx_to_offset(_radix, _idx)))
void *__genradix_ptr(struct __genradix *, size_t);
/**
* genradix_ptr - get a pointer to a genradix entry
* @_radix: genradix to access
* @_idx: index to fetch
*
* Returns a pointer to entry at @_idx, or NULL if that entry does not exist.
*/
#define genradix_ptr(_radix, _idx) \
(__genradix_cast(_radix) \
__genradix_ptr(&(_radix)->tree, \
__genradix_idx_to_offset(_radix, _idx)))
void *__genradix_ptr_alloc(struct __genradix *, size_t,
struct genradix_node **, gfp_t);
#define genradix_ptr_alloc_inlined(_radix, _idx, _gfp) \
(__genradix_cast(_radix) \
(__genradix_ptr_inlined(&(_radix)->tree, \
__genradix_idx_to_offset(_radix, _idx)) ?: \
__genradix_ptr_alloc(&(_radix)->tree, \
__genradix_idx_to_offset(_radix, _idx), \
NULL, _gfp)))
#define genradix_ptr_alloc_preallocated_inlined(_radix, _idx, _new_node, _gfp)\
(__genradix_cast(_radix) \
(__genradix_ptr_inlined(&(_radix)->tree, \
__genradix_idx_to_offset(_radix, _idx)) ?: \
__genradix_ptr_alloc(&(_radix)->tree, \
__genradix_idx_to_offset(_radix, _idx), \
_new_node, _gfp)))
/**
* genradix_ptr_alloc - get a pointer to a genradix entry, allocating it
* if necessary
* @_radix: genradix to access
* @_idx: index to fetch
* @_gfp: gfp mask
*
* Returns a pointer to entry at @_idx, or NULL on allocation failure
*/
#define genradix_ptr_alloc(_radix, _idx, _gfp) \
(__genradix_cast(_radix) \
__genradix_ptr_alloc(&(_radix)->tree, \
__genradix_idx_to_offset(_radix, _idx), \
NULL, _gfp))
#define genradix_ptr_alloc_preallocated(_radix, _idx, _new_node, _gfp)\
(__genradix_cast(_radix) \
__genradix_ptr_alloc(&(_radix)->tree, \
__genradix_idx_to_offset(_radix, _idx), \
_new_node, _gfp))
struct genradix_iter {
size_t offset;
size_t pos;
};
/**
* genradix_iter_init - initialize a genradix_iter
* @_radix: genradix that will be iterated over
* @_idx: index to start iterating from
*/
#define genradix_iter_init(_radix, _idx) \
((struct genradix_iter) { \
.pos = (_idx), \
.offset = __genradix_idx_to_offset((_radix), (_idx)),\
})
void *__genradix_iter_peek(struct genradix_iter *, struct __genradix *, size_t);
/**
* genradix_iter_peek - get first entry at or above iterator's current
* position
* @_iter: a genradix_iter
* @_radix: genradix being iterated over
*
* If no more entries exist at or above @_iter's current position, returns NULL
*/
#define genradix_iter_peek(_iter, _radix) \
(__genradix_cast(_radix) \
__genradix_iter_peek(_iter, &(_radix)->tree, \
__genradix_objs_per_page(_radix)))
void *__genradix_iter_peek_prev(struct genradix_iter *, struct __genradix *,
size_t, size_t);
/**
* genradix_iter_peek_prev - get first entry at or below iterator's current
* position
* @_iter: a genradix_iter
* @_radix: genradix being iterated over
*
* If no more entries exist at or below @_iter's current position, returns NULL
*/
#define genradix_iter_peek_prev(_iter, _radix) \
(__genradix_cast(_radix) \
__genradix_iter_peek_prev(_iter, &(_radix)->tree, \
__genradix_objs_per_page(_radix), \
__genradix_obj_size(_radix) + \
__genradix_page_remainder(_radix)))
static inline void __genradix_iter_advance(struct genradix_iter *iter,
size_t obj_size)
{
if (iter->offset + obj_size < iter->offset) {
iter->offset = SIZE_MAX;
iter->pos = SIZE_MAX;
return;
}
iter->offset += obj_size;
if (!is_power_of_2(obj_size) &&
(iter->offset & (GENRADIX_NODE_SIZE - 1)) + obj_size > GENRADIX_NODE_SIZE)
iter->offset = round_up(iter->offset, GENRADIX_NODE_SIZE);
iter->pos++;
}
#define genradix_iter_advance(_iter, _radix) \
__genradix_iter_advance(_iter, __genradix_obj_size(_radix))
static inline void __genradix_iter_rewind(struct genradix_iter *iter,
size_t obj_size)
{
if (iter->offset == 0 ||
iter->offset == SIZE_MAX) {
iter->offset = SIZE_MAX;
return;
}
if ((iter->offset & (GENRADIX_NODE_SIZE - 1)) == 0)
iter->offset -= GENRADIX_NODE_SIZE % obj_size;
iter->offset -= obj_size;
iter->pos--;
}
#define genradix_iter_rewind(_iter, _radix) \
__genradix_iter_rewind(_iter, __genradix_obj_size(_radix))
#define genradix_for_each_from(_radix, _iter, _p, _start) \
for (_iter = genradix_iter_init(_radix, _start); \
(_p = genradix_iter_peek(&_iter, _radix)) != NULL; \
genradix_iter_advance(&_iter, _radix))
/**
* genradix_for_each - iterate over entry in a genradix
* @_radix: genradix to iterate over
* @_iter: a genradix_iter to track current position
* @_p: pointer to genradix entry type
*
* On every iteration, @_p will point to the current entry, and @_iter.pos
* will be the current entry's index.
*/
#define genradix_for_each(_radix, _iter, _p) \
genradix_for_each_from(_radix, _iter, _p, 0)
#define genradix_last_pos(_radix) \
(SIZE_MAX / GENRADIX_NODE_SIZE * __genradix_objs_per_page(_radix) - 1)
/**
* genradix_for_each_reverse - iterate over entry in a genradix, reverse order
* @_radix: genradix to iterate over
* @_iter: a genradix_iter to track current position
* @_p: pointer to genradix entry type
*
* On every iteration, @_p will point to the current entry, and @_iter.pos
* will be the current entry's index.
*/
#define genradix_for_each_reverse(_radix, _iter, _p) \
for (_iter = genradix_iter_init(_radix, genradix_last_pos(_radix));\
(_p = genradix_iter_peek_prev(&_iter, _radix)) != NULL;\
genradix_iter_rewind(&_iter, _radix))
int __genradix_prealloc(struct __genradix *, size_t, gfp_t);
/**
* genradix_prealloc - preallocate entries in a generic radix tree
* @_radix: genradix to preallocate
* @_nr: number of entries to preallocate
* @_gfp: gfp mask
*
* Returns 0 on success, -ENOMEM on failure
*/
#define genradix_prealloc(_radix, _nr, _gfp) \
__genradix_prealloc(&(_radix)->tree, \
__genradix_idx_to_offset(_radix, _nr + 1),\
_gfp)
#endif /* _LINUX_GENERIC_RADIX_TREE_H */
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