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Based on 1 normalized pattern(s): 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 extracted by the scancode license scanner the SPDX license identifier GPL-2.0-or-later has been chosen to replace the boilerplate/reference in 77 file(s). Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Allison Randal <allison@lohutok.net> Reviewed-by: Armijn Hemel <armijn@tjaldur.nl> Reviewed-by: Richard Fontana <rfontana@redhat.com> Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190527070032.837555891@linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
478 lines
16 KiB
C
478 lines
16 KiB
C
/* SPDX-License-Identifier: GPL-2.0-or-later */
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/*
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* Copyright (C) 2001 Momchil Velikov
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* Portions Copyright (C) 2001 Christoph Hellwig
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* Copyright (C) 2006 Nick Piggin
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* Copyright (C) 2012 Konstantin Khlebnikov
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*/
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#ifndef _LINUX_RADIX_TREE_H
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#define _LINUX_RADIX_TREE_H
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#include <linux/bitops.h>
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#include <linux/kernel.h>
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#include <linux/list.h>
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#include <linux/preempt.h>
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#include <linux/rcupdate.h>
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#include <linux/spinlock.h>
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#include <linux/types.h>
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#include <linux/xarray.h>
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/* Keep unconverted code working */
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#define radix_tree_root xarray
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#define radix_tree_node xa_node
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/*
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* The bottom two bits of the slot determine how the remaining bits in the
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* slot are interpreted:
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*
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* 00 - data pointer
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* 10 - internal entry
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* x1 - value entry
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*
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* The internal entry may be a pointer to the next level in the tree, a
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* sibling entry, or an indicator that the entry in this slot has been moved
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* to another location in the tree and the lookup should be restarted. While
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* NULL fits the 'data pointer' pattern, it means that there is no entry in
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* the tree for this index (no matter what level of the tree it is found at).
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* This means that storing a NULL entry in the tree is the same as deleting
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* the entry from the tree.
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*/
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#define RADIX_TREE_ENTRY_MASK 3UL
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#define RADIX_TREE_INTERNAL_NODE 2UL
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static inline bool radix_tree_is_internal_node(void *ptr)
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{
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return ((unsigned long)ptr & RADIX_TREE_ENTRY_MASK) ==
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RADIX_TREE_INTERNAL_NODE;
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}
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/*** radix-tree API starts here ***/
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#define RADIX_TREE_MAP_SHIFT XA_CHUNK_SHIFT
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#define RADIX_TREE_MAP_SIZE (1UL << RADIX_TREE_MAP_SHIFT)
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#define RADIX_TREE_MAP_MASK (RADIX_TREE_MAP_SIZE-1)
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#define RADIX_TREE_MAX_TAGS XA_MAX_MARKS
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#define RADIX_TREE_TAG_LONGS XA_MARK_LONGS
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#define RADIX_TREE_INDEX_BITS (8 /* CHAR_BIT */ * sizeof(unsigned long))
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#define RADIX_TREE_MAX_PATH (DIV_ROUND_UP(RADIX_TREE_INDEX_BITS, \
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RADIX_TREE_MAP_SHIFT))
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/* The IDR tag is stored in the low bits of xa_flags */
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#define ROOT_IS_IDR ((__force gfp_t)4)
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/* The top bits of xa_flags are used to store the root tags */
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#define ROOT_TAG_SHIFT (__GFP_BITS_SHIFT)
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#define RADIX_TREE_INIT(name, mask) XARRAY_INIT(name, mask)
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#define RADIX_TREE(name, mask) \
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struct radix_tree_root name = RADIX_TREE_INIT(name, mask)
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#define INIT_RADIX_TREE(root, mask) xa_init_flags(root, mask)
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static inline bool radix_tree_empty(const struct radix_tree_root *root)
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{
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return root->xa_head == NULL;
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}
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/**
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* struct radix_tree_iter - radix tree iterator state
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*
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* @index: index of current slot
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* @next_index: one beyond the last index for this chunk
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* @tags: bit-mask for tag-iterating
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* @node: node that contains current slot
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*
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* This radix tree iterator works in terms of "chunks" of slots. A chunk is a
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* subinterval of slots contained within one radix tree leaf node. It is
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* described by a pointer to its first slot and a struct radix_tree_iter
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* which holds the chunk's position in the tree and its size. For tagged
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* iteration radix_tree_iter also holds the slots' bit-mask for one chosen
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* radix tree tag.
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*/
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struct radix_tree_iter {
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unsigned long index;
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unsigned long next_index;
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unsigned long tags;
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struct radix_tree_node *node;
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};
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/**
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* Radix-tree synchronization
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*
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* The radix-tree API requires that users provide all synchronisation (with
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* specific exceptions, noted below).
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*
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* Synchronization of access to the data items being stored in the tree, and
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* management of their lifetimes must be completely managed by API users.
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*
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* For API usage, in general,
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* - any function _modifying_ the tree or tags (inserting or deleting
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* items, setting or clearing tags) must exclude other modifications, and
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* exclude any functions reading the tree.
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* - any function _reading_ the tree or tags (looking up items or tags,
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* gang lookups) must exclude modifications to the tree, but may occur
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* concurrently with other readers.
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*
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* The notable exceptions to this rule are the following functions:
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* __radix_tree_lookup
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* radix_tree_lookup
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* radix_tree_lookup_slot
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* radix_tree_tag_get
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* radix_tree_gang_lookup
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* radix_tree_gang_lookup_tag
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* radix_tree_gang_lookup_tag_slot
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* radix_tree_tagged
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*
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* The first 7 functions are able to be called locklessly, using RCU. The
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* caller must ensure calls to these functions are made within rcu_read_lock()
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* regions. Other readers (lock-free or otherwise) and modifications may be
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* running concurrently.
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*
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* It is still required that the caller manage the synchronization and lifetimes
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* of the items. So if RCU lock-free lookups are used, typically this would mean
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* that the items have their own locks, or are amenable to lock-free access; and
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* that the items are freed by RCU (or only freed after having been deleted from
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* the radix tree *and* a synchronize_rcu() grace period).
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*
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* (Note, rcu_assign_pointer and rcu_dereference are not needed to control
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* access to data items when inserting into or looking up from the radix tree)
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*
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* Note that the value returned by radix_tree_tag_get() may not be relied upon
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* if only the RCU read lock is held. Functions to set/clear tags and to
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* delete nodes running concurrently with it may affect its result such that
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* two consecutive reads in the same locked section may return different
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* values. If reliability is required, modification functions must also be
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* excluded from concurrency.
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*
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* radix_tree_tagged is able to be called without locking or RCU.
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*/
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/**
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* radix_tree_deref_slot - dereference a slot
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* @slot: slot pointer, returned by radix_tree_lookup_slot
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*
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* For use with radix_tree_lookup_slot(). Caller must hold tree at least read
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* locked across slot lookup and dereference. Not required if write lock is
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* held (ie. items cannot be concurrently inserted).
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*
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* radix_tree_deref_retry must be used to confirm validity of the pointer if
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* only the read lock is held.
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*
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* Return: entry stored in that slot.
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*/
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static inline void *radix_tree_deref_slot(void __rcu **slot)
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{
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return rcu_dereference(*slot);
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}
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/**
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* radix_tree_deref_slot_protected - dereference a slot with tree lock held
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* @slot: slot pointer, returned by radix_tree_lookup_slot
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*
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* Similar to radix_tree_deref_slot. The caller does not hold the RCU read
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* lock but it must hold the tree lock to prevent parallel updates.
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*
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* Return: entry stored in that slot.
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*/
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static inline void *radix_tree_deref_slot_protected(void __rcu **slot,
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spinlock_t *treelock)
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{
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return rcu_dereference_protected(*slot, lockdep_is_held(treelock));
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}
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/**
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* radix_tree_deref_retry - check radix_tree_deref_slot
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* @arg: pointer returned by radix_tree_deref_slot
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* Returns: 0 if retry is not required, otherwise retry is required
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*
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* radix_tree_deref_retry must be used with radix_tree_deref_slot.
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*/
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static inline int radix_tree_deref_retry(void *arg)
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{
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return unlikely(radix_tree_is_internal_node(arg));
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}
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/**
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* radix_tree_exception - radix_tree_deref_slot returned either exception?
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* @arg: value returned by radix_tree_deref_slot
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* Returns: 0 if well-aligned pointer, non-0 if either kind of exception.
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*/
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static inline int radix_tree_exception(void *arg)
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{
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return unlikely((unsigned long)arg & RADIX_TREE_ENTRY_MASK);
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}
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int radix_tree_insert(struct radix_tree_root *, unsigned long index,
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void *);
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void *__radix_tree_lookup(const struct radix_tree_root *, unsigned long index,
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struct radix_tree_node **nodep, void __rcu ***slotp);
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void *radix_tree_lookup(const struct radix_tree_root *, unsigned long);
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void __rcu **radix_tree_lookup_slot(const struct radix_tree_root *,
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unsigned long index);
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void __radix_tree_replace(struct radix_tree_root *, struct radix_tree_node *,
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void __rcu **slot, void *entry);
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void radix_tree_iter_replace(struct radix_tree_root *,
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const struct radix_tree_iter *, void __rcu **slot, void *entry);
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void radix_tree_replace_slot(struct radix_tree_root *,
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void __rcu **slot, void *entry);
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void radix_tree_iter_delete(struct radix_tree_root *,
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struct radix_tree_iter *iter, void __rcu **slot);
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void *radix_tree_delete_item(struct radix_tree_root *, unsigned long, void *);
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void *radix_tree_delete(struct radix_tree_root *, unsigned long);
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unsigned int radix_tree_gang_lookup(const struct radix_tree_root *,
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void **results, unsigned long first_index,
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unsigned int max_items);
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int radix_tree_preload(gfp_t gfp_mask);
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int radix_tree_maybe_preload(gfp_t gfp_mask);
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void radix_tree_init(void);
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void *radix_tree_tag_set(struct radix_tree_root *,
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unsigned long index, unsigned int tag);
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void *radix_tree_tag_clear(struct radix_tree_root *,
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unsigned long index, unsigned int tag);
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int radix_tree_tag_get(const struct radix_tree_root *,
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unsigned long index, unsigned int tag);
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void radix_tree_iter_tag_clear(struct radix_tree_root *,
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const struct radix_tree_iter *iter, unsigned int tag);
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unsigned int radix_tree_gang_lookup_tag(const struct radix_tree_root *,
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void **results, unsigned long first_index,
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unsigned int max_items, unsigned int tag);
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unsigned int radix_tree_gang_lookup_tag_slot(const struct radix_tree_root *,
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void __rcu ***results, unsigned long first_index,
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unsigned int max_items, unsigned int tag);
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int radix_tree_tagged(const struct radix_tree_root *, unsigned int tag);
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static inline void radix_tree_preload_end(void)
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{
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preempt_enable();
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}
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void __rcu **idr_get_free(struct radix_tree_root *root,
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struct radix_tree_iter *iter, gfp_t gfp,
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unsigned long max);
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enum {
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RADIX_TREE_ITER_TAG_MASK = 0x0f, /* tag index in lower nybble */
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RADIX_TREE_ITER_TAGGED = 0x10, /* lookup tagged slots */
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RADIX_TREE_ITER_CONTIG = 0x20, /* stop at first hole */
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};
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/**
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* radix_tree_iter_init - initialize radix tree iterator
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*
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* @iter: pointer to iterator state
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* @start: iteration starting index
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* Returns: NULL
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*/
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static __always_inline void __rcu **
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radix_tree_iter_init(struct radix_tree_iter *iter, unsigned long start)
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{
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/*
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* Leave iter->tags uninitialized. radix_tree_next_chunk() will fill it
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* in the case of a successful tagged chunk lookup. If the lookup was
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* unsuccessful or non-tagged then nobody cares about ->tags.
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*
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* Set index to zero to bypass next_index overflow protection.
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* See the comment in radix_tree_next_chunk() for details.
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*/
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iter->index = 0;
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iter->next_index = start;
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return NULL;
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}
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/**
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* radix_tree_next_chunk - find next chunk of slots for iteration
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*
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* @root: radix tree root
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* @iter: iterator state
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* @flags: RADIX_TREE_ITER_* flags and tag index
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* Returns: pointer to chunk first slot, or NULL if there no more left
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*
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* This function looks up the next chunk in the radix tree starting from
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* @iter->next_index. It returns a pointer to the chunk's first slot.
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* Also it fills @iter with data about chunk: position in the tree (index),
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* its end (next_index), and constructs a bit mask for tagged iterating (tags).
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*/
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void __rcu **radix_tree_next_chunk(const struct radix_tree_root *,
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struct radix_tree_iter *iter, unsigned flags);
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/**
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* radix_tree_iter_lookup - look up an index in the radix tree
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* @root: radix tree root
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* @iter: iterator state
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* @index: key to look up
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*
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* If @index is present in the radix tree, this function returns the slot
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* containing it and updates @iter to describe the entry. If @index is not
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* present, it returns NULL.
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*/
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static inline void __rcu **
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radix_tree_iter_lookup(const struct radix_tree_root *root,
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struct radix_tree_iter *iter, unsigned long index)
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{
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radix_tree_iter_init(iter, index);
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return radix_tree_next_chunk(root, iter, RADIX_TREE_ITER_CONTIG);
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}
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/**
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* radix_tree_iter_find - find a present entry
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* @root: radix tree root
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* @iter: iterator state
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* @index: start location
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*
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* This function returns the slot containing the entry with the lowest index
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* which is at least @index. If @index is larger than any present entry, this
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* function returns NULL. The @iter is updated to describe the entry found.
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*/
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static inline void __rcu **
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radix_tree_iter_find(const struct radix_tree_root *root,
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struct radix_tree_iter *iter, unsigned long index)
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{
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radix_tree_iter_init(iter, index);
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return radix_tree_next_chunk(root, iter, 0);
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}
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/**
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* radix_tree_iter_retry - retry this chunk of the iteration
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* @iter: iterator state
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*
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* If we iterate over a tree protected only by the RCU lock, a race
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* against deletion or creation may result in seeing a slot for which
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* radix_tree_deref_retry() returns true. If so, call this function
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* and continue the iteration.
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*/
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static inline __must_check
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void __rcu **radix_tree_iter_retry(struct radix_tree_iter *iter)
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{
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iter->next_index = iter->index;
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iter->tags = 0;
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return NULL;
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}
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static inline unsigned long
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__radix_tree_iter_add(struct radix_tree_iter *iter, unsigned long slots)
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{
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return iter->index + slots;
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}
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/**
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* radix_tree_iter_resume - resume iterating when the chunk may be invalid
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* @slot: pointer to current slot
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* @iter: iterator state
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* Returns: New slot pointer
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*
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* If the iterator needs to release then reacquire a lock, the chunk may
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* have been invalidated by an insertion or deletion. Call this function
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* before releasing the lock to continue the iteration from the next index.
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*/
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void __rcu **__must_check radix_tree_iter_resume(void __rcu **slot,
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struct radix_tree_iter *iter);
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/**
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* radix_tree_chunk_size - get current chunk size
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*
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* @iter: pointer to radix tree iterator
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* Returns: current chunk size
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*/
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static __always_inline long
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radix_tree_chunk_size(struct radix_tree_iter *iter)
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{
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return iter->next_index - iter->index;
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}
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/**
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* radix_tree_next_slot - find next slot in chunk
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*
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* @slot: pointer to current slot
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* @iter: pointer to interator state
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* @flags: RADIX_TREE_ITER_*, should be constant
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* Returns: pointer to next slot, or NULL if there no more left
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*
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* This function updates @iter->index in the case of a successful lookup.
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* For tagged lookup it also eats @iter->tags.
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*
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* There are several cases where 'slot' can be passed in as NULL to this
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* function. These cases result from the use of radix_tree_iter_resume() or
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* radix_tree_iter_retry(). In these cases we don't end up dereferencing
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* 'slot' because either:
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* a) we are doing tagged iteration and iter->tags has been set to 0, or
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* b) we are doing non-tagged iteration, and iter->index and iter->next_index
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* have been set up so that radix_tree_chunk_size() returns 1 or 0.
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*/
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static __always_inline void __rcu **radix_tree_next_slot(void __rcu **slot,
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struct radix_tree_iter *iter, unsigned flags)
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{
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if (flags & RADIX_TREE_ITER_TAGGED) {
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iter->tags >>= 1;
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if (unlikely(!iter->tags))
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return NULL;
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if (likely(iter->tags & 1ul)) {
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iter->index = __radix_tree_iter_add(iter, 1);
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slot++;
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goto found;
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}
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if (!(flags & RADIX_TREE_ITER_CONTIG)) {
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unsigned offset = __ffs(iter->tags);
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iter->tags >>= offset++;
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iter->index = __radix_tree_iter_add(iter, offset);
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slot += offset;
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goto found;
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}
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} else {
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long count = radix_tree_chunk_size(iter);
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while (--count > 0) {
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slot++;
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iter->index = __radix_tree_iter_add(iter, 1);
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if (likely(*slot))
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goto found;
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if (flags & RADIX_TREE_ITER_CONTIG) {
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/* forbid switching to the next chunk */
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iter->next_index = 0;
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break;
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}
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}
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}
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return NULL;
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found:
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return slot;
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}
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/**
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* radix_tree_for_each_slot - iterate over non-empty slots
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*
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* @slot: the void** variable for pointer to slot
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* @root: the struct radix_tree_root pointer
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* @iter: the struct radix_tree_iter pointer
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* @start: iteration starting index
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*
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* @slot points to radix tree slot, @iter->index contains its index.
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*/
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#define radix_tree_for_each_slot(slot, root, iter, start) \
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for (slot = radix_tree_iter_init(iter, start) ; \
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slot || (slot = radix_tree_next_chunk(root, iter, 0)) ; \
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slot = radix_tree_next_slot(slot, iter, 0))
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/**
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* radix_tree_for_each_tagged - iterate over tagged slots
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*
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* @slot: the void** variable for pointer to slot
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* @root: the struct radix_tree_root pointer
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* @iter: the struct radix_tree_iter pointer
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* @start: iteration starting index
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* @tag: tag index
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*
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* @slot points to radix tree slot, @iter->index contains its index.
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*/
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#define radix_tree_for_each_tagged(slot, root, iter, start, tag) \
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for (slot = radix_tree_iter_init(iter, start) ; \
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slot || (slot = radix_tree_next_chunk(root, iter, \
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RADIX_TREE_ITER_TAGGED | tag)) ; \
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slot = radix_tree_next_slot(slot, iter, \
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RADIX_TREE_ITER_TAGGED | tag))
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#endif /* _LINUX_RADIX_TREE_H */
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