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#include <linux/atomic.h>
#include <linux/export.h>
#include <linux/generic-radix-tree.h>
#include <linux/gfp.h>
#include <linux/kmemleak.h>
#define GENRADIX_ARY (GENRADIX_NODE_SIZE / sizeof(struct genradix_node *))
#define GENRADIX_ARY_SHIFT ilog2(GENRADIX_ARY)
struct genradix_node {
union {
/* Interior node: */
struct genradix_node *children[GENRADIX_ARY];
/* Leaf: */
u8 data[GENRADIX_NODE_SIZE];
};
};
static inline int genradix_depth_shift(unsigned depth)
{
return GENRADIX_NODE_SHIFT + GENRADIX_ARY_SHIFT * depth;
}
/*
* Returns size (of data, in bytes) that a tree of a given depth holds:
*/
static inline size_t genradix_depth_size(unsigned depth)
{
return 1UL << genradix_depth_shift(depth);
}
/* depth that's needed for a genradix that can address up to ULONG_MAX: */
#define GENRADIX_MAX_DEPTH \
DIV_ROUND_UP(BITS_PER_LONG - GENRADIX_NODE_SHIFT, GENRADIX_ARY_SHIFT)
#define GENRADIX_DEPTH_MASK \
((unsigned long) (roundup_pow_of_two(GENRADIX_MAX_DEPTH + 1) - 1))
static inline unsigned genradix_root_to_depth(struct genradix_root *r)
{
return (unsigned long) r & GENRADIX_DEPTH_MASK;
}
static inline struct genradix_node *genradix_root_to_node(struct genradix_root *r)
{
return (void *) ((unsigned long) r & ~GENRADIX_DEPTH_MASK);
}
/*
* Returns pointer to the specified byte @offset within @radix, or NULL if not
* allocated
*/
void *__genradix_ptr(struct __genradix *radix, size_t offset)
{
struct genradix_root *r = READ_ONCE(radix->root);
struct genradix_node *n = genradix_root_to_node(r);
unsigned level = genradix_root_to_depth(r);
if (ilog2(offset) >= genradix_depth_shift(level))
return NULL;
while (1) {
if (!n)
return NULL;
if (!level)
break;
level--;
n = n->children[offset >> genradix_depth_shift(level)];
offset &= genradix_depth_size(level) - 1;
}
return &n->data[offset];
}
EXPORT_SYMBOL(__genradix_ptr);
static inline struct genradix_node *genradix_alloc_node(gfp_t gfp_mask)
{
return kzalloc(GENRADIX_NODE_SIZE, gfp_mask);
}
static inline void genradix_free_node(struct genradix_node *node)
{
kfree(node);
}
/*
* Returns pointer to the specified byte @offset within @radix, allocating it if
* necessary - newly allocated slots are always zeroed out:
*/
void *__genradix_ptr_alloc(struct __genradix *radix, size_t offset,
gfp_t gfp_mask)
{
struct genradix_root *v = READ_ONCE(radix->root);
struct genradix_node *n, *new_node = NULL;
unsigned level;
/* Increase tree depth if necessary: */
while (1) {
struct genradix_root *r = v, *new_root;
n = genradix_root_to_node(r);
level = genradix_root_to_depth(r);
if (n && ilog2(offset) < genradix_depth_shift(level))
break;
if (!new_node) {
new_node = genradix_alloc_node(gfp_mask);
if (!new_node)
return NULL;
}
new_node->children[0] = n;
new_root = ((struct genradix_root *)
((unsigned long) new_node | (n ? level + 1 : 0)));
if ((v = cmpxchg_release(&radix->root, r, new_root)) == r) {
v = new_root;
new_node = NULL;
} else {
new_node->children[0] = NULL;
}
}
while (level--) {
struct genradix_node **p =
&n->children[offset >> genradix_depth_shift(level)];
offset &= genradix_depth_size(level) - 1;
n = READ_ONCE(*p);
if (!n) {
if (!new_node) {
new_node = genradix_alloc_node(gfp_mask);
if (!new_node)
return NULL;
}
if (!(n = cmpxchg_release(p, NULL, new_node)))
swap(n, new_node);
}
}
if (new_node)
genradix_free_node(new_node);
return &n->data[offset];
}
EXPORT_SYMBOL(__genradix_ptr_alloc);
void *__genradix_iter_peek(struct genradix_iter *iter,
struct __genradix *radix,
size_t objs_per_page)
{
struct genradix_root *r;
struct genradix_node *n;
unsigned level, i;
if (iter->offset == SIZE_MAX)
return NULL;
restart:
r = READ_ONCE(radix->root);
if (!r)
return NULL;
n = genradix_root_to_node(r);
level = genradix_root_to_depth(r);
if (ilog2(iter->offset) >= genradix_depth_shift(level))
return NULL;
while (level) {
level--;
i = (iter->offset >> genradix_depth_shift(level)) &
(GENRADIX_ARY - 1);
while (!n->children[i]) {
size_t objs_per_ptr = genradix_depth_size(level);
if (iter->offset + objs_per_ptr < iter->offset) {
iter->offset = SIZE_MAX;
iter->pos = SIZE_MAX;
return NULL;
}
i++;
iter->offset = round_down(iter->offset + objs_per_ptr,
objs_per_ptr);
iter->pos = (iter->offset >> GENRADIX_NODE_SHIFT) *
objs_per_page;
if (i == GENRADIX_ARY)
goto restart;
}
n = n->children[i];
}
return &n->data[iter->offset & (GENRADIX_NODE_SIZE - 1)];
}
EXPORT_SYMBOL(__genradix_iter_peek);
void *__genradix_iter_peek_prev(struct genradix_iter *iter,
struct __genradix *radix,
size_t objs_per_page,
size_t obj_size_plus_page_remainder)
{
struct genradix_root *r;
struct genradix_node *n;
unsigned level, i;
if (iter->offset == SIZE_MAX)
return NULL;
restart:
r = READ_ONCE(radix->root);
if (!r)
return NULL;
n = genradix_root_to_node(r);
level = genradix_root_to_depth(r);
if (ilog2(iter->offset) >= genradix_depth_shift(level)) {
iter->offset = genradix_depth_size(level);
iter->pos = (iter->offset >> GENRADIX_NODE_SHIFT) * objs_per_page;
iter->offset -= obj_size_plus_page_remainder;
iter->pos--;
}
while (level) {
level--;
i = (iter->offset >> genradix_depth_shift(level)) &
(GENRADIX_ARY - 1);
while (!n->children[i]) {
size_t objs_per_ptr = genradix_depth_size(level);
iter->offset = round_down(iter->offset, objs_per_ptr);
iter->pos = (iter->offset >> GENRADIX_NODE_SHIFT) * objs_per_page;
if (!iter->offset)
return NULL;
iter->offset -= obj_size_plus_page_remainder;
iter->pos--;
if (!i)
goto restart;
--i;
}
n = n->children[i];
}
return &n->data[iter->offset & (GENRADIX_NODE_SIZE - 1)];
}
EXPORT_SYMBOL(__genradix_iter_peek_prev);
static void genradix_free_recurse(struct genradix_node *n, unsigned level)
{
if (level) {
unsigned i;
for (i = 0; i < GENRADIX_ARY; i++)
if (n->children[i])
genradix_free_recurse(n->children[i], level - 1);
}
genradix_free_node(n);
}
int __genradix_prealloc(struct __genradix *radix, size_t size,
gfp_t gfp_mask)
{
size_t offset;
for (offset = 0; offset < size; offset += GENRADIX_NODE_SIZE)
if (!__genradix_ptr_alloc(radix, offset, gfp_mask))
return -ENOMEM;
return 0;
}
EXPORT_SYMBOL(__genradix_prealloc);
void __genradix_free(struct __genradix *radix)
{
struct genradix_root *r = xchg(&radix->root, NULL);
genradix_free_recurse(genradix_root_to_node(r),
genradix_root_to_depth(r));
}
EXPORT_SYMBOL(__genradix_free);
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