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#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
* PAGE_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/kernel.h>
#include <linux/log2.h>
struct genradix_root;
struct __genradix {
struct genradix_root *root;
};
/*
* NOTE: currently, sizeof(_type) must not be larger than PAGE_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 > PAGE_SIZE);
else
BUG_ON(obj_size > PAGE_SIZE);
if (!is_power_of_2(obj_size)) {
size_t objs_per_page = PAGE_SIZE / obj_size;
return (idx / objs_per_page) * PAGE_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_idx_to_offset(_radix, _idx) \
__idx_to_offset(_idx, __genradix_obj_size(_radix))
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, gfp_t);
/**
* 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), \
_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, \
PAGE_SIZE / __genradix_obj_size(_radix)))
static inline void __genradix_iter_advance(struct genradix_iter *iter,
size_t obj_size)
{
iter->offset += obj_size;
if (!is_power_of_2(obj_size) &&
(iter->offset & (PAGE_SIZE - 1)) + obj_size > PAGE_SIZE)
iter->offset = round_up(iter->offset, PAGE_SIZE);
iter->pos++;
}
#define genradix_iter_advance(_iter, _radix) \
__genradix_iter_advance(_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)
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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