cregit-Linux how code gets into the kernel

Release 4.7 include/linux/assoc_array_priv.h

Directory: include/linux
/* Private definitions for the generic associative array implementation.
 *
 * See Documentation/assoc_array.txt for information.
 *
 * Copyright (C) 2013 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public Licence
 * as published by the Free Software Foundation; either version
 * 2 of the Licence, or (at your option) any later version.
 */

#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; }

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static inline bool assoc_array_ptr_is_leaf(const struct assoc_array_ptr *x) { return !assoc_array_ptr_is_meta(x); }

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static inline bool assoc_array_ptr_is_shortcut(const struct assoc_array_ptr *x) { return (unsigned long)x & ASSOC_ARRAY_PTR_SUBTYPE_MASK; }

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static inline bool assoc_array_ptr_is_node(const struct assoc_array_ptr *x) { return !assoc_array_ptr_is_shortcut(x); }

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static inline void *assoc_array_ptr_to_leaf(const struct assoc_array_ptr *x) { return (void *)((unsigned long)x & ~ASSOC_ARRAY_PTR_TYPE_MASK); }

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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); }

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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); }

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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); }

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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); }

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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); }

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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); }

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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); }

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#endif /* CONFIG_ASSOCIATIVE_ARRAY */ #endif /* _LINUX_ASSOC_ARRAY_PRIV_H */

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Directory: include/linux
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