#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
+ *
+ * - genradix_ptr_alloc(radix, idx, gfp) - gets a pointer to an entry,
+ * allocating it if necessary
*
- * A generic radix tree has all nodes of size PAGE_SIZE - both leaves and
- * interior nodes.
+ * - 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_node;
+struct genradix_root;
struct __genradix {
- struct genradix_node *root;
- size_t depth;
+ struct genradix_root __rcu *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, \
} \
}
#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; \
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;
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;
};
+/**
+ * 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), \
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, \
static inline void __genradix_iter_advance(struct genradix_iter *iter,
size_t obj_size)
{
+ size_t new_offset = iter->offset + obj_size;
+
+ if (new_offset < 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))
+#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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