| #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/log2.h> |
| #include <linux/math.h> |
| #include <linux/types.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 */ |