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