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231 lines
6.4 KiB
231 lines
6.4 KiB
#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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* PAGE_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/kernel.h> |
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#include <linux/log2.h> |
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struct genradix_root; |
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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 PAGE_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 > PAGE_SIZE); |
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else |
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BUG_ON(obj_size > PAGE_SIZE); |
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if (!is_power_of_2(obj_size)) { |
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size_t objs_per_page = PAGE_SIZE / obj_size; |
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return (idx / objs_per_page) * PAGE_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_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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PAGE_SIZE / __genradix_obj_size(_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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iter->offset += obj_size; |
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if (!is_power_of_2(obj_size) && |
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(iter->offset & (PAGE_SIZE - 1)) + obj_size > PAGE_SIZE) |
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iter->offset = round_up(iter->offset, PAGE_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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#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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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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