cregit-Linux how code gets into the kernel

Release 4.7 include/linux/radix-tree.h

Directory: include/linux
/*
 * Copyright (C) 2001 Momchil Velikov
 * Portions Copyright (C) 2001 Christoph Hellwig
 * Copyright (C) 2006 Nick Piggin
 * Copyright (C) 2012 Konstantin Khlebnikov
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2, or (at
 * your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */
#ifndef _LINUX_RADIX_TREE_H

#define _LINUX_RADIX_TREE_H

#include <linux/bitops.h>
#include <linux/preempt.h>
#include <linux/types.h>
#include <linux/bug.h>
#include <linux/kernel.h>
#include <linux/rcupdate.h>

/*
 * The bottom two bits of the slot determine how the remaining bits in the
 * slot are interpreted:
 *
 * 00 - data pointer
 * 01 - internal entry
 * 10 - exceptional entry
 * 11 - locked exceptional entry
 *
 * The internal entry may be a pointer to the next level in the tree, a
 * sibling entry, or an indicator that the entry in this slot has been moved
 * to another location in the tree and the lookup should be restarted.  While
 * NULL fits the 'data pointer' pattern, it means that there is no entry in
 * the tree for this index (no matter what level of the tree it is found at).
 * This means that you cannot store NULL in the tree as a value for the index.
 */

#define RADIX_TREE_ENTRY_MASK		3UL

#define RADIX_TREE_INTERNAL_NODE	1UL

/*
 * Most users of the radix tree store pointers but shmem/tmpfs stores swap
 * entries in the same tree.  They are marked as exceptional entries to
 * distinguish them from pointers to struct page.
 * EXCEPTIONAL_ENTRY tests the bit, EXCEPTIONAL_SHIFT shifts content past it.
 */

#define RADIX_TREE_EXCEPTIONAL_ENTRY	2

#define RADIX_TREE_EXCEPTIONAL_SHIFT	2


static inline bool radix_tree_is_internal_node(void *ptr) { return ((unsigned long)ptr & RADIX_TREE_ENTRY_MASK) == RADIX_TREE_INTERNAL_NODE; }

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nick pigginnick piggin1770.83%125.00%
matthew wilcoxmatthew wilcox729.17%375.00%
Total24100.00%4100.00%

/*** radix-tree API starts here ***/ #define RADIX_TREE_MAX_TAGS 3 #ifndef RADIX_TREE_MAP_SHIFT #define RADIX_TREE_MAP_SHIFT (CONFIG_BASE_SMALL ? 4 : 6) #endif #define RADIX_TREE_MAP_SIZE (1UL << RADIX_TREE_MAP_SHIFT) #define RADIX_TREE_MAP_MASK (RADIX_TREE_MAP_SIZE-1) #define RADIX_TREE_TAG_LONGS \ ((RADIX_TREE_MAP_SIZE + BITS_PER_LONG - 1) / BITS_PER_LONG) #define RADIX_TREE_INDEX_BITS (8 /* CHAR_BIT */ * sizeof(unsigned long)) #define RADIX_TREE_MAX_PATH (DIV_ROUND_UP(RADIX_TREE_INDEX_BITS, \ RADIX_TREE_MAP_SHIFT)) /* Internally used bits of node->count */ #define RADIX_TREE_COUNT_SHIFT (RADIX_TREE_MAP_SHIFT + 1) #define RADIX_TREE_COUNT_MASK ((1UL << RADIX_TREE_COUNT_SHIFT) - 1) struct radix_tree_node { unsigned char shift; /* Bits remaining in each slot */ unsigned char offset; /* Slot offset in parent */ unsigned int count; union { struct { /* Used when ascending tree */ struct radix_tree_node *parent; /* For tree user */ void *private_data; }; /* Used when freeing node */ struct rcu_head rcu_head; }; /* For tree user */ struct list_head private_list; void __rcu *slots[RADIX_TREE_MAP_SIZE]; unsigned long tags[RADIX_TREE_MAX_TAGS][RADIX_TREE_TAG_LONGS]; }; /* root tags are stored in gfp_mask, shifted by __GFP_BITS_SHIFT */ struct radix_tree_root { gfp_t gfp_mask; struct radix_tree_node __rcu *rnode; }; #define RADIX_TREE_INIT(mask) { \ .gfp_mask = (mask), \ .rnode = NULL, \ } #define RADIX_TREE(name, mask) \ struct radix_tree_root name = RADIX_TREE_INIT(mask) #define INIT_RADIX_TREE(root, mask) \ do { \ (root)->gfp_mask = (mask); \ (root)->rnode = NULL; \ } while (0)
static inline bool radix_tree_empty(struct radix_tree_root *root) { return root->rnode == NULL; }

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matthew wilcoxmatthew wilcox19100.00%1100.00%
Total19100.00%1100.00%

/** * Radix-tree synchronization * * The radix-tree API requires that users provide all synchronisation (with * specific exceptions, noted below). * * Synchronization of access to the data items being stored in the tree, and * management of their lifetimes must be completely managed by API users. * * For API usage, in general, * - any function _modifying_ the tree or tags (inserting or deleting * items, setting or clearing tags) must exclude other modifications, and * exclude any functions reading the tree. * - any function _reading_ the tree or tags (looking up items or tags, * gang lookups) must exclude modifications to the tree, but may occur * concurrently with other readers. * * The notable exceptions to this rule are the following functions: * __radix_tree_lookup * radix_tree_lookup * radix_tree_lookup_slot * radix_tree_tag_get * radix_tree_gang_lookup * radix_tree_gang_lookup_slot * radix_tree_gang_lookup_tag * radix_tree_gang_lookup_tag_slot * radix_tree_tagged * * The first 8 functions are able to be called locklessly, using RCU. The * caller must ensure calls to these functions are made within rcu_read_lock() * regions. Other readers (lock-free or otherwise) and modifications may be * running concurrently. * * It is still required that the caller manage the synchronization and lifetimes * of the items. So if RCU lock-free lookups are used, typically this would mean * that the items have their own locks, or are amenable to lock-free access; and * that the items are freed by RCU (or only freed after having been deleted from * the radix tree *and* a synchronize_rcu() grace period). * * (Note, rcu_assign_pointer and rcu_dereference are not needed to control * access to data items when inserting into or looking up from the radix tree) * * Note that the value returned by radix_tree_tag_get() may not be relied upon * if only the RCU read lock is held. Functions to set/clear tags and to * delete nodes running concurrently with it may affect its result such that * two consecutive reads in the same locked section may return different * values. If reliability is required, modification functions must also be * excluded from concurrency. * * radix_tree_tagged is able to be called without locking or RCU. */ /** * radix_tree_deref_slot - dereference a slot * @pslot: pointer to slot, returned by radix_tree_lookup_slot * Returns: item that was stored in that slot with any direct pointer flag * removed. * * For use with radix_tree_lookup_slot(). Caller must hold tree at least read * locked across slot lookup and dereference. Not required if write lock is * held (ie. items cannot be concurrently inserted). * * radix_tree_deref_retry must be used to confirm validity of the pointer if * only the read lock is held. */
static inline void *radix_tree_deref_slot(void **pslot) { return rcu_dereference(*pslot); }

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nick pigginnick piggin20100.00%3100.00%
Total20100.00%3100.00%

/** * radix_tree_deref_slot_protected - dereference a slot without RCU lock but with tree lock held * @pslot: pointer to slot, returned by radix_tree_lookup_slot * Returns: item that was stored in that slot with any direct pointer flag * removed. * * Similar to radix_tree_deref_slot but only used during migration when a pages * mapping is being moved. The caller does not hold the RCU read lock but it * must hold the tree lock to prevent parallel updates. */
static inline void *radix_tree_deref_slot_protected(void **pslot, spinlock_t *treelock) { return rcu_dereference_protected(*pslot, lockdep_is_held(treelock)); }

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mel gormanmel gorman29100.00%1100.00%
Total29100.00%1100.00%

/** * radix_tree_deref_retry - check radix_tree_deref_slot * @arg: pointer returned by radix_tree_deref_slot * Returns: 0 if retry is not required, otherwise retry is required * * radix_tree_deref_retry must be used with radix_tree_deref_slot. */
static inline int radix_tree_deref_retry(void *arg) { return unlikely(radix_tree_is_internal_node(arg)); }

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nick pigginnick piggin1785.00%360.00%
matthew wilcoxmatthew wilcox315.00%240.00%
Total20100.00%5100.00%

/** * radix_tree_exceptional_entry - radix_tree_deref_slot gave exceptional entry? * @arg: value returned by radix_tree_deref_slot * Returns: 0 if well-aligned pointer, non-0 if exceptional entry. */
static inline int radix_tree_exceptional_entry(void *arg) { /* Not unlikely because radix_tree_exception often tested first */ return (unsigned long)arg & RADIX_TREE_EXCEPTIONAL_ENTRY; }

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hugh dickinshugh dickins21100.00%1100.00%
Total21100.00%1100.00%

/** * radix_tree_exception - radix_tree_deref_slot returned either exception? * @arg: value returned by radix_tree_deref_slot * Returns: 0 if well-aligned pointer, non-0 if either kind of exception. */
static inline int radix_tree_exception(void *arg) { return unlikely((unsigned long)arg & RADIX_TREE_ENTRY_MASK); }

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hugh dickinshugh dickins2295.65%150.00%
matthew wilcoxmatthew wilcox14.35%150.00%
Total23100.00%2100.00%

/** * radix_tree_replace_slot - replace item in a slot * @pslot: pointer to slot, returned by radix_tree_lookup_slot * @item: new item to store in the slot. * * For use with radix_tree_lookup_slot(). Caller must hold tree write locked * across slot lookup and replacement. */
static inline void radix_tree_replace_slot(void **pslot, void *item) { BUG_ON(radix_tree_is_internal_node(item)); rcu_assign_pointer(*pslot, item); }

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nick pigginnick piggin3196.88%150.00%
matthew wilcoxmatthew wilcox13.12%150.00%
Total32100.00%2100.00%

int __radix_tree_create(struct radix_tree_root *root, unsigned long index, unsigned order, struct radix_tree_node **nodep, void ***slotp); int __radix_tree_insert(struct radix_tree_root *, unsigned long index, unsigned order, void *);
static inline int radix_tree_insert(struct radix_tree_root *root, unsigned long index, void *entry) { return __radix_tree_insert(root, index, 0, entry); }

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matthew wilcoxmatthew wilcox32100.00%1100.00%
Total32100.00%1100.00%

void *__radix_tree_lookup(struct radix_tree_root *root, unsigned long index, struct radix_tree_node **nodep, void ***slotp); void *radix_tree_lookup(struct radix_tree_root *, unsigned long); void **radix_tree_lookup_slot(struct radix_tree_root *, unsigned long); bool __radix_tree_delete_node(struct radix_tree_root *root, struct radix_tree_node *node); void *radix_tree_delete_item(struct radix_tree_root *, unsigned long, void *); void *radix_tree_delete(struct radix_tree_root *, unsigned long); struct radix_tree_node *radix_tree_replace_clear_tags( struct radix_tree_root *root, unsigned long index, void *entry); unsigned int radix_tree_gang_lookup(struct radix_tree_root *root, void **results, unsigned long first_index, unsigned int max_items); unsigned int radix_tree_gang_lookup_slot(struct radix_tree_root *root, void ***results, unsigned long *indices, unsigned long first_index, unsigned int max_items); int radix_tree_preload(gfp_t gfp_mask); int radix_tree_maybe_preload(gfp_t gfp_mask); void radix_tree_init(void); void *radix_tree_tag_set(struct radix_tree_root *root, unsigned long index, unsigned int tag); void *radix_tree_tag_clear(struct radix_tree_root *root, unsigned long index, unsigned int tag); int radix_tree_tag_get(struct radix_tree_root *root, unsigned long index, unsigned int tag); unsigned int radix_tree_gang_lookup_tag(struct radix_tree_root *root, void **results, unsigned long first_index, unsigned int max_items, unsigned int tag); unsigned int radix_tree_gang_lookup_tag_slot(struct radix_tree_root *root, void ***results, unsigned long first_index, unsigned int max_items, unsigned int tag); unsigned long radix_tree_range_tag_if_tagged(struct radix_tree_root *root, unsigned long *first_indexp, unsigned long last_index, unsigned long nr_to_tag, unsigned int fromtag, unsigned int totag); int radix_tree_tagged(struct radix_tree_root *root, unsigned int tag); unsigned long radix_tree_locate_item(struct radix_tree_root *root, void *item);
static inline void radix_tree_preload_end(void) { preempt_enable(); }

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andrew mortonandrew morton12100.00%1100.00%
Total12100.00%1100.00%

/** * struct radix_tree_iter - radix tree iterator state * * @index: index of current slot * @next_index: one beyond the last index for this chunk * @tags: bit-mask for tag-iterating * @shift: shift for the node that holds our slots * * This radix tree iterator works in terms of "chunks" of slots. A chunk is a * subinterval of slots contained within one radix tree leaf node. It is * described by a pointer to its first slot and a struct radix_tree_iter * which holds the chunk's position in the tree and its size. For tagged * iteration radix_tree_iter also holds the slots' bit-mask for one chosen * radix tree tag. */ struct radix_tree_iter { unsigned long index; unsigned long next_index; unsigned long tags; #ifdef CONFIG_RADIX_TREE_MULTIORDER unsigned int shift; #endif };
static inline unsigned int iter_shift(struct radix_tree_iter *iter) { #ifdef CONFIG_RADIX_TREE_MULTIORDER return iter->shift; #else return 0; #endif }

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ross zwislerross zwisler28100.00%1100.00%
Total28100.00%1100.00%

#define RADIX_TREE_ITER_TAG_MASK 0x00FF /* tag index in lower byte */ #define RADIX_TREE_ITER_TAGGED 0x0100 /* lookup tagged slots */ #define RADIX_TREE_ITER_CONTIG 0x0200 /* stop at first hole */ /** * radix_tree_iter_init - initialize radix tree iterator * * @iter: pointer to iterator state * @start: iteration starting index * Returns: NULL */
static __always_inline void ** radix_tree_iter_init(struct radix_tree_iter *iter, unsigned long start) { /* * Leave iter->tags uninitialized. radix_tree_next_chunk() will fill it * in the case of a successful tagged chunk lookup. If the lookup was * unsuccessful or non-tagged then nobody cares about ->tags. * * Set index to zero to bypass next_index overflow protection. * See the comment in radix_tree_next_chunk() for details. */ iter->index = 0; iter->next_index = start; return NULL; }

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konstantin khlebnikovkonstantin khlebnikov34100.00%1100.00%
Total34100.00%1100.00%

/** * radix_tree_next_chunk - find next chunk of slots for iteration * * @root: radix tree root * @iter: iterator state * @flags: RADIX_TREE_ITER_* flags and tag index * Returns: pointer to chunk first slot, or NULL if there no more left * * This function looks up the next chunk in the radix tree starting from * @iter->next_index. It returns a pointer to the chunk's first slot. * Also it fills @iter with data about chunk: position in the tree (index), * its end (next_index), and constructs a bit mask for tagged iterating (tags). */ void **radix_tree_next_chunk(struct radix_tree_root *root, struct radix_tree_iter *iter, unsigned flags); /** * radix_tree_iter_retry - retry this chunk of the iteration * @iter: iterator state * * If we iterate over a tree protected only by the RCU lock, a race * against deletion or creation may result in seeing a slot for which * radix_tree_deref_retry() returns true. If so, call this function * and continue the iteration. */
static inline __must_check void **radix_tree_iter_retry(struct radix_tree_iter *iter) { iter->next_index = iter->index; iter->tags = 0; return NULL; }

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matthew wilcoxmatthew wilcox2681.25%266.67%
andrey ryabininandrey ryabinin618.75%133.33%
Total32100.00%3100.00%


static inline unsigned long __radix_tree_iter_add(struct radix_tree_iter *iter, unsigned long slots) { return iter->index + (slots << iter_shift(iter)); }

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ross zwislerross zwisler31100.00%1100.00%
Total31100.00%1100.00%

/** * radix_tree_iter_next - resume iterating when the chunk may be invalid * @iter: iterator state * * If the iterator needs to release then reacquire a lock, the chunk may * have been invalidated by an insertion or deletion. Call this function * to continue the iteration from the next index. */
static inline __must_check void **radix_tree_iter_next(struct radix_tree_iter *iter) { iter->next_index = __radix_tree_iter_add(iter, 1); iter->tags = 0; return NULL; }

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matthew wilcoxmatthew wilcox3188.57%266.67%
ross zwislerross zwisler411.43%133.33%
Total35100.00%3100.00%

/** * radix_tree_chunk_size - get current chunk size * * @iter: pointer to radix tree iterator * Returns: current chunk size */
static __always_inline long radix_tree_chunk_size(struct radix_tree_iter *iter) { return (iter->next_index - iter->index) >> iter_shift(iter); }

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konstantin khlebnikovkonstantin khlebnikov1967.86%266.67%
ross zwislerross zwisler932.14%133.33%
Total28100.00%3100.00%


static inline struct radix_tree_node *entry_to_node(void *ptr) { return (void *)((unsigned long)ptr & ~RADIX_TREE_INTERNAL_NODE); }

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ross zwislerross zwisler2379.31%125.00%
matthew wilcoxmatthew wilcox413.79%250.00%
konstantin khlebnikovkonstantin khlebnikov26.90%125.00%
Total29100.00%4100.00%

/** * radix_tree_next_slot - find next slot in chunk * * @slot: pointer to current slot * @iter: pointer to interator state * @flags: RADIX_TREE_ITER_*, should be constant * Returns: pointer to next slot, or NULL if there no more left * * This function updates @iter->index in the case of a successful lookup. * For tagged lookup it also eats @iter->tags. */
static __always_inline void ** radix_tree_next_slot(void **slot, struct radix_tree_iter *iter, unsigned flags) { if (flags & RADIX_TREE_ITER_TAGGED) { void *canon = slot; iter->tags >>= 1; if (unlikely(!iter->tags)) return NULL; while (IS_ENABLED(CONFIG_RADIX_TREE_MULTIORDER) && radix_tree_is_internal_node(slot[1])) { if (entry_to_node(slot[1]) == canon) { iter->tags >>= 1; iter->index = __radix_tree_iter_add(iter, 1); slot++; continue; } iter->next_index = __radix_tree_iter_add(iter, 1); return NULL; } if (likely(iter->tags & 1ul)) { iter->index = __radix_tree_iter_add(iter, 1); return slot + 1; } if (!(flags & RADIX_TREE_ITER_CONTIG)) { unsigned offset = __ffs(iter->tags); iter->tags >>= offset; iter->index = __radix_tree_iter_add(iter, offset + 1); return slot + offset + 1; } } else { long count = radix_tree_chunk_size(iter); void *canon = slot; while (--count > 0) { slot++; iter->index = __radix_tree_iter_add(iter, 1); if (IS_ENABLED(CONFIG_RADIX_TREE_MULTIORDER) && radix_tree_is_internal_node(*slot)) { if (entry_to_node(*slot) == canon) continue; iter->next_index = iter->index; break; } if (likely(*slot)) return slot; if (flags & RADIX_TREE_ITER_CONTIG) { /* forbid switching to the next chunk */ iter->next_index = 0; break; } } } return NULL; }

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konstantin khlebnikovkonstantin khlebnikov15450.99%350.00%
ross zwislerross zwisler14447.68%116.67%
matthew wilcoxmatthew wilcox41.32%233.33%
Total302100.00%6100.00%

/** * radix_tree_for_each_slot - iterate over non-empty slots * * @slot: the void** variable for pointer to slot * @root: the struct radix_tree_root pointer * @iter: the struct radix_tree_iter pointer * @start: iteration starting index * * @slot points to radix tree slot, @iter->index contains its index. */ #define radix_tree_for_each_slot(slot, root, iter, start) \ for (slot = radix_tree_iter_init(iter, start) ; \ slot || (slot = radix_tree_next_chunk(root, iter, 0)) ; \ slot = radix_tree_next_slot(slot, iter, 0)) /** * radix_tree_for_each_contig - iterate over contiguous slots * * @slot: the void** variable for pointer to slot * @root: the struct radix_tree_root pointer * @iter: the struct radix_tree_iter pointer * @start: iteration starting index * * @slot points to radix tree slot, @iter->index contains its index. */ #define radix_tree_for_each_contig(slot, root, iter, start) \ for (slot = radix_tree_iter_init(iter, start) ; \ slot || (slot = radix_tree_next_chunk(root, iter, \ RADIX_TREE_ITER_CONTIG)) ; \ slot = radix_tree_next_slot(slot, iter, \ RADIX_TREE_ITER_CONTIG)) /** * radix_tree_for_each_tagged - iterate over tagged slots * * @slot: the void** variable for pointer to slot * @root: the struct radix_tree_root pointer * @iter: the struct radix_tree_iter pointer * @start: iteration starting index * @tag: tag index * * @slot points to radix tree slot, @iter->index contains its index. */ #define radix_tree_for_each_tagged(slot, root, iter, start, tag) \ for (slot = radix_tree_iter_init(iter, start) ; \ slot || (slot = radix_tree_next_chunk(root, iter, \ RADIX_TREE_ITER_TAGGED | tag)) ; \ slot = radix_tree_next_slot(slot, iter, \ RADIX_TREE_ITER_TAGGED)) #endif /* _LINUX_RADIX_TREE_H */

Overall Contributors

PersonTokensPropCommitsCommitProp
konstantin khlebnikovkonstantin khlebnikov31221.27%36.38%
ross zwislerross zwisler25217.18%24.26%
andrew mortonandrew morton22415.27%510.64%
matthew wilcoxmatthew wilcox17812.13%1327.66%
johannes weinerjohannes weiner17612.00%36.38%
nick pigginnick piggin15210.36%612.77%
hugh dickinshugh dickins724.91%24.26%
jan karajan kara392.66%36.38%
mel gormanmel gorman302.04%12.13%
hans reiserhans reiser130.89%12.13%
andrey ryabininandrey ryabinin60.41%12.13%
jonathan corbetjonathan corbet50.34%12.13%
paul gortmakerpaul gortmaker30.20%12.13%
al viroal viro20.14%24.26%
arnd bergmannarnd bergmann10.07%12.13%
wu fengguangwu fengguang10.07%12.13%
adam barthadam barth10.07%12.13%
Total1467100.00%47100.00%
Directory: include/linux
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