#ifndef _LINUX_GENERIC_RADIX_TREE_H
#define _LINUX_GENERIC_RADIX_TREE_H
-/*
- * Generic radix trees/sparse arrays:
+/**
+ * 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
*
- * A generic radix tree has all nodes of size PAGE_SIZE - both leaves and
- * interior nodes.
+ * - 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 <linux/page.h>
+#include <asm/page.h>
#include <linux/bug.h>
-#include <linux/kernel.h>
+#include <linux/limits.h>
#include <linux/log2.h>
+#include <linux/math.h>
+#include <linux/types.h>
-struct genradix_node;
+struct genradix_root;
struct __genradix {
- struct genradix_node *root;
- size_t depth;
+ struct genradix_root *root;
};
/*
- * NOTE: currently, sizeof(_type) must be a power of two and not larger than
- * PAGE_SIZE:
+ * NOTE: currently, sizeof(_type) must not be larger than PAGE_SIZE:
*/
#define __GENRADIX_INITIALIZER \
{ \
.tree = { \
.root = NULL, \
- .depth = 0, \
} \
}
* genradix.
*/
-#define DECLARE_GENRADIX_TYPE(_name, _type) \
-struct _name { \
- struct __genradix tree; \
- _type type[0] __aligned(1); \
-}
-
-#define DECLARE_GENRADIX(_name, _type) \
+#define GENRADIX(_type) \
struct { \
struct __genradix tree; \
_type type[0] __aligned(1); \
-} _name
+}
#define DEFINE_GENRADIX(_name, _type) \
- DECLARE_GENRADIX(_name, _type) = __GENRADIX_INITIALIZER
+ 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; \
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)
{
- BUILD_BUG_ON(obj_size > PAGE_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;
#define __genradix_cast(_radix) (typeof((_radix)->type[0]) *)
#define __genradix_obj_size(_radix) sizeof((_radix)->type[0])
+#define __genradix_objs_per_page(_radix) \
+ (PAGE_SIZE / sizeof((_radix)->type[0]))
+#define __genradix_page_remainder(_radix) \
+ (PAGE_SIZE % 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);
-/* Returns a pointer to element at @_idx */
+/**
+ * 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, \
void *__genradix_ptr_alloc(struct __genradix *, size_t, gfp_t);
-/* Returns a pointer to element at @_idx, allocating it if necessary */
+/**
+ * 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, \
size_t pos;
};
-static inline void genradix_iter_init(struct genradix_iter *iter)
-{
- iter->offset = 0;
- iter->pos = 0;
-}
+/**
+ * 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)))
+ __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) &&
#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 & (PAGE_SIZE - 1)) == 0)
+ iter->offset -= PAGE_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 / PAGE_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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