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Diffstat (limited to '')
| -rw-r--r-- | include/linux/assoc_array_priv.h | 178 |
1 files changed, 178 insertions, 0 deletions
diff --git a/include/linux/assoc_array_priv.h b/include/linux/assoc_array_priv.h new file mode 100644 index 000000000..dca733ef6 --- /dev/null +++ b/include/linux/assoc_array_priv.h @@ -0,0 +1,178 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ +/* Private definitions for the generic associative array implementation. + * + * See Documentation/core-api/assoc_array.rst for information. + * + * Copyright (C) 2013 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + */ + +#ifndef _LINUX_ASSOC_ARRAY_PRIV_H +#define _LINUX_ASSOC_ARRAY_PRIV_H + +#ifdef CONFIG_ASSOCIATIVE_ARRAY + +#include <linux/assoc_array.h> + +#define ASSOC_ARRAY_FAN_OUT 16 /* Number of slots per node */ +#define ASSOC_ARRAY_FAN_MASK (ASSOC_ARRAY_FAN_OUT - 1) +#define ASSOC_ARRAY_LEVEL_STEP (ilog2(ASSOC_ARRAY_FAN_OUT)) +#define ASSOC_ARRAY_LEVEL_STEP_MASK (ASSOC_ARRAY_LEVEL_STEP - 1) +#define ASSOC_ARRAY_KEY_CHUNK_MASK (ASSOC_ARRAY_KEY_CHUNK_SIZE - 1) +#define ASSOC_ARRAY_KEY_CHUNK_SHIFT (ilog2(BITS_PER_LONG)) + +/* + * Undefined type representing a pointer with type information in the bottom + * two bits. + */ +struct assoc_array_ptr; + +/* + * An N-way node in the tree. + * + * Each slot contains one of four things: + * + * (1) Nothing (NULL). + * + * (2) A leaf object (pointer types 0). + * + * (3) A next-level node (pointer type 1, subtype 0). + * + * (4) A shortcut (pointer type 1, subtype 1). + * + * The tree is optimised for search-by-ID, but permits reasonable iteration + * also. + * + * The tree is navigated by constructing an index key consisting of an array of + * segments, where each segment is ilog2(ASSOC_ARRAY_FAN_OUT) bits in size. + * + * The segments correspond to levels of the tree (the first segment is used at + * level 0, the second at level 1, etc.). + */ +struct assoc_array_node { + struct assoc_array_ptr *back_pointer; + u8 parent_slot; + struct assoc_array_ptr *slots[ASSOC_ARRAY_FAN_OUT]; + unsigned long nr_leaves_on_branch; +}; + +/* + * A shortcut through the index space out to where a collection of nodes/leaves + * with the same IDs live. + */ +struct assoc_array_shortcut { + struct assoc_array_ptr *back_pointer; + int parent_slot; + int skip_to_level; + struct assoc_array_ptr *next_node; + unsigned long index_key[]; +}; + +/* + * Preallocation cache. + */ +struct assoc_array_edit { + struct rcu_head rcu; + struct assoc_array *array; + const struct assoc_array_ops *ops; + const struct assoc_array_ops *ops_for_excised_subtree; + struct assoc_array_ptr *leaf; + struct assoc_array_ptr **leaf_p; + struct assoc_array_ptr *dead_leaf; + struct assoc_array_ptr *new_meta[3]; + struct assoc_array_ptr *excised_meta[1]; + struct assoc_array_ptr *excised_subtree; + struct assoc_array_ptr **set_backpointers[ASSOC_ARRAY_FAN_OUT]; + struct assoc_array_ptr *set_backpointers_to; + struct assoc_array_node *adjust_count_on; + long adjust_count_by; + struct { + struct assoc_array_ptr **ptr; + struct assoc_array_ptr *to; + } set[2]; + struct { + u8 *p; + u8 to; + } set_parent_slot[1]; + u8 segment_cache[ASSOC_ARRAY_FAN_OUT + 1]; +}; + +/* + * Internal tree member pointers are marked in the bottom one or two bits to + * indicate what type they are so that we don't have to look behind every + * pointer to see what it points to. + * + * We provide functions to test type annotations and to create and translate + * the annotated pointers. + */ +#define ASSOC_ARRAY_PTR_TYPE_MASK 0x1UL +#define ASSOC_ARRAY_PTR_LEAF_TYPE 0x0UL /* Points to leaf (or nowhere) */ +#define ASSOC_ARRAY_PTR_META_TYPE 0x1UL /* Points to node or shortcut */ +#define ASSOC_ARRAY_PTR_SUBTYPE_MASK 0x2UL +#define ASSOC_ARRAY_PTR_NODE_SUBTYPE 0x0UL +#define ASSOC_ARRAY_PTR_SHORTCUT_SUBTYPE 0x2UL + +static inline bool assoc_array_ptr_is_meta(const struct assoc_array_ptr *x) +{ + return (unsigned long)x & ASSOC_ARRAY_PTR_TYPE_MASK; +} +static inline bool assoc_array_ptr_is_leaf(const struct assoc_array_ptr *x) +{ + return !assoc_array_ptr_is_meta(x); +} +static inline bool assoc_array_ptr_is_shortcut(const struct assoc_array_ptr *x) +{ + return (unsigned long)x & ASSOC_ARRAY_PTR_SUBTYPE_MASK; +} +static inline bool assoc_array_ptr_is_node(const struct assoc_array_ptr *x) +{ + return !assoc_array_ptr_is_shortcut(x); +} + +static inline void *assoc_array_ptr_to_leaf(const struct assoc_array_ptr *x) +{ + return (void *)((unsigned long)x & ~ASSOC_ARRAY_PTR_TYPE_MASK); +} + +static inline +unsigned long __assoc_array_ptr_to_meta(const struct assoc_array_ptr *x) +{ + return (unsigned long)x & + ~(ASSOC_ARRAY_PTR_SUBTYPE_MASK | ASSOC_ARRAY_PTR_TYPE_MASK); +} +static inline +struct assoc_array_node *assoc_array_ptr_to_node(const struct assoc_array_ptr *x) +{ + return (struct assoc_array_node *)__assoc_array_ptr_to_meta(x); +} +static inline +struct assoc_array_shortcut *assoc_array_ptr_to_shortcut(const struct assoc_array_ptr *x) +{ + return (struct assoc_array_shortcut *)__assoc_array_ptr_to_meta(x); +} + +static inline +struct assoc_array_ptr *__assoc_array_x_to_ptr(const void *p, unsigned long t) +{ + return (struct assoc_array_ptr *)((unsigned long)p | t); +} +static inline +struct assoc_array_ptr *assoc_array_leaf_to_ptr(const void *p) +{ + return __assoc_array_x_to_ptr(p, ASSOC_ARRAY_PTR_LEAF_TYPE); +} +static inline +struct assoc_array_ptr *assoc_array_node_to_ptr(const struct assoc_array_node *p) +{ + return __assoc_array_x_to_ptr( + p, ASSOC_ARRAY_PTR_META_TYPE | ASSOC_ARRAY_PTR_NODE_SUBTYPE); +} +static inline +struct assoc_array_ptr *assoc_array_shortcut_to_ptr(const struct assoc_array_shortcut *p) +{ + return __assoc_array_x_to_ptr( + p, ASSOC_ARRAY_PTR_META_TYPE | ASSOC_ARRAY_PTR_SHORTCUT_SUBTYPE); +} + +#endif /* CONFIG_ASSOCIATIVE_ARRAY */ +#endif /* _LINUX_ASSOC_ARRAY_PRIV_H */ |