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+/* SPDX-License-Identifier: GPL-2.0+ */
+#ifndef _LINUX_MAPLE_TREE_H
+#define _LINUX_MAPLE_TREE_H
+/*
+ * Maple Tree - An RCU-safe adaptive tree for storing ranges
+ * Copyright (c) 2018-2022 Oracle
+ * Authors: Liam R. Howlett <Liam.Howlett@Oracle.com>
+ * Matthew Wilcox <willy@infradead.org>
+ */
+
+#include <linux/kernel.h>
+#include <linux/rcupdate.h>
+#include <linux/spinlock.h>
+/* #define CONFIG_MAPLE_RCU_DISABLED */
+/* #define CONFIG_DEBUG_MAPLE_TREE_VERBOSE */
+
+/*
+ * Allocated nodes are mutable until they have been inserted into the tree,
+ * at which time they cannot change their type until they have been removed
+ * from the tree and an RCU grace period has passed.
+ *
+ * Removed nodes have their ->parent set to point to themselves. RCU readers
+ * check ->parent before relying on the value that they loaded from the
+ * slots array. This lets us reuse the slots array for the RCU head.
+ *
+ * Nodes in the tree point to their parent unless bit 0 is set.
+ */
+#if defined(CONFIG_64BIT) || defined(BUILD_VDSO32_64)
+/* 64bit sizes */
+#define MAPLE_NODE_SLOTS 31 /* 256 bytes including ->parent */
+#define MAPLE_RANGE64_SLOTS 16 /* 256 bytes */
+#define MAPLE_ARANGE64_SLOTS 10 /* 240 bytes */
+#define MAPLE_ARANGE64_META_MAX 15 /* Out of range for metadata */
+#define MAPLE_ALLOC_SLOTS (MAPLE_NODE_SLOTS - 1)
+#else
+/* 32bit sizes */
+#define MAPLE_NODE_SLOTS 63 /* 256 bytes including ->parent */
+#define MAPLE_RANGE64_SLOTS 32 /* 256 bytes */
+#define MAPLE_ARANGE64_SLOTS 21 /* 240 bytes */
+#define MAPLE_ARANGE64_META_MAX 31 /* Out of range for metadata */
+#define MAPLE_ALLOC_SLOTS (MAPLE_NODE_SLOTS - 2)
+#endif /* defined(CONFIG_64BIT) || defined(BUILD_VDSO32_64) */
+
+#define MAPLE_NODE_MASK 255UL
+
+/*
+ * The node->parent of the root node has bit 0 set and the rest of the pointer
+ * is a pointer to the tree itself. No more bits are available in this pointer
+ * (on m68k, the data structure may only be 2-byte aligned).
+ *
+ * Internal non-root nodes can only have maple_range_* nodes as parents. The
+ * parent pointer is 256B aligned like all other tree nodes. When storing a 32
+ * or 64 bit values, the offset can fit into 4 bits. The 16 bit values need an
+ * extra bit to store the offset. This extra bit comes from a reuse of the last
+ * bit in the node type. This is possible by using bit 1 to indicate if bit 2
+ * is part of the type or the slot.
+ *
+ * Once the type is decided, the decision of an allocation range type or a range
+ * type is done by examining the immutable tree flag for the MAPLE_ALLOC_RANGE
+ * flag.
+ *
+ * Node types:
+ * 0x??1 = Root
+ * 0x?00 = 16 bit nodes
+ * 0x010 = 32 bit nodes
+ * 0x110 = 64 bit nodes
+ *
+ * Slot size and location in the parent pointer:
+ * type : slot location
+ * 0x??1 : Root
+ * 0x?00 : 16 bit values, type in 0-1, slot in 2-6
+ * 0x010 : 32 bit values, type in 0-2, slot in 3-6
+ * 0x110 : 64 bit values, type in 0-2, slot in 3-6
+ */
+
+/*
+ * This metadata is used to optimize the gap updating code and in reverse
+ * searching for gaps or any other code that needs to find the end of the data.
+ */
+struct maple_metadata {
+ unsigned char end;
+ unsigned char gap;
+};
+
+/*
+ * Leaf nodes do not store pointers to nodes, they store user data. Users may
+ * store almost any bit pattern. As noted above, the optimisation of storing an
+ * entry at 0 in the root pointer cannot be done for data which have the bottom
+ * two bits set to '10'. We also reserve values with the bottom two bits set to
+ * '10' which are below 4096 (ie 2, 6, 10 .. 4094) for internal use. Some APIs
+ * return errnos as a negative errno shifted right by two bits and the bottom
+ * two bits set to '10', and while choosing to store these values in the array
+ * is not an error, it may lead to confusion if you're testing for an error with
+ * mas_is_err().
+ *
+ * Non-leaf nodes store the type of the node pointed to (enum maple_type in bits
+ * 3-6), bit 2 is reserved. That leaves bits 0-1 unused for now.
+ *
+ * In regular B-Tree terms, pivots are called keys. The term pivot is used to
+ * indicate that the tree is specifying ranges, Pivots may appear in the
+ * subtree with an entry attached to the value whereas keys are unique to a
+ * specific position of a B-tree. Pivot values are inclusive of the slot with
+ * the same index.
+ */
+
+struct maple_range_64 {
+ struct maple_pnode *parent;
+ unsigned long pivot[MAPLE_RANGE64_SLOTS - 1];
+ union {
+ void __rcu *slot[MAPLE_RANGE64_SLOTS];
+ struct {
+ void __rcu *pad[MAPLE_RANGE64_SLOTS - 1];
+ struct maple_metadata meta;
+ };
+ };
+};
+
+/*
+ * At tree creation time, the user can specify that they're willing to trade off
+ * storing fewer entries in a tree in return for storing more information in
+ * each node.
+ *
+ * The maple tree supports recording the largest range of NULL entries available
+ * in this node, also called gaps. This optimises the tree for allocating a
+ * range.
+ */
+struct maple_arange_64 {
+ struct maple_pnode *parent;
+ unsigned long pivot[MAPLE_ARANGE64_SLOTS - 1];
+ void __rcu *slot[MAPLE_ARANGE64_SLOTS];
+ unsigned long gap[MAPLE_ARANGE64_SLOTS];
+ struct maple_metadata meta;
+};
+
+struct maple_alloc {
+ unsigned long total;
+ unsigned char node_count;
+ unsigned int request_count;
+ struct maple_alloc *slot[MAPLE_ALLOC_SLOTS];
+};
+
+struct maple_topiary {
+ struct maple_pnode *parent;
+ struct maple_enode *next; /* Overlaps the pivot */
+};
+
+enum maple_type {
+ maple_dense,
+ maple_leaf_64,
+ maple_range_64,
+ maple_arange_64,
+};
+
+
+/**
+ * DOC: Maple tree flags
+ *
+ * * MT_FLAGS_ALLOC_RANGE - Track gaps in this tree
+ * * MT_FLAGS_USE_RCU - Operate in RCU mode
+ * * MT_FLAGS_HEIGHT_OFFSET - The position of the tree height in the flags
+ * * MT_FLAGS_HEIGHT_MASK - The mask for the maple tree height value
+ * * MT_FLAGS_LOCK_MASK - How the mt_lock is used
+ * * MT_FLAGS_LOCK_IRQ - Acquired irq-safe
+ * * MT_FLAGS_LOCK_BH - Acquired bh-safe
+ * * MT_FLAGS_LOCK_EXTERN - mt_lock is not used
+ *
+ * MAPLE_HEIGHT_MAX The largest height that can be stored
+ */
+#define MT_FLAGS_ALLOC_RANGE 0x01
+#define MT_FLAGS_USE_RCU 0x02
+#define MT_FLAGS_HEIGHT_OFFSET 0x02
+#define MT_FLAGS_HEIGHT_MASK 0x7C
+#define MT_FLAGS_LOCK_MASK 0x300
+#define MT_FLAGS_LOCK_IRQ 0x100
+#define MT_FLAGS_LOCK_BH 0x200
+#define MT_FLAGS_LOCK_EXTERN 0x300
+
+#define MAPLE_HEIGHT_MAX 31
+
+
+#define MAPLE_NODE_TYPE_MASK 0x0F
+#define MAPLE_NODE_TYPE_SHIFT 0x03
+
+#define MAPLE_RESERVED_RANGE 4096
+
+#ifdef CONFIG_LOCKDEP
+typedef struct lockdep_map *lockdep_map_p;
+#define mt_lock_is_held(mt) lock_is_held(mt->ma_external_lock)
+#define mt_set_external_lock(mt, lock) \
+ (mt)->ma_external_lock = &(lock)->dep_map
+#else
+typedef struct { /* nothing */ } lockdep_map_p;
+#define mt_lock_is_held(mt) 1
+#define mt_set_external_lock(mt, lock) do { } while (0)
+#endif
+
+/*
+ * If the tree contains a single entry at index 0, it is usually stored in
+ * tree->ma_root. To optimise for the page cache, an entry which ends in '00',
+ * '01' or '11' is stored in the root, but an entry which ends in '10' will be
+ * stored in a node. Bits 3-6 are used to store enum maple_type.
+ *
+ * The flags are used both to store some immutable information about this tree
+ * (set at tree creation time) and dynamic information set under the spinlock.
+ *
+ * Another use of flags are to indicate global states of the tree. This is the
+ * case with the MAPLE_USE_RCU flag, which indicates the tree is currently in
+ * RCU mode. This mode was added to allow the tree to reuse nodes instead of
+ * re-allocating and RCU freeing nodes when there is a single user.
+ */
+struct maple_tree {
+ union {
+ spinlock_t ma_lock;
+ lockdep_map_p ma_external_lock;
+ };
+ void __rcu *ma_root;
+ unsigned int ma_flags;
+};
+
+/**
+ * MTREE_INIT() - Initialize a maple tree
+ * @name: The maple tree name
+ * @__flags: The maple tree flags
+ *
+ */
+#define MTREE_INIT(name, __flags) { \
+ .ma_lock = __SPIN_LOCK_UNLOCKED((name).ma_lock), \
+ .ma_flags = __flags, \
+ .ma_root = NULL, \
+}
+
+/**
+ * MTREE_INIT_EXT() - Initialize a maple tree with an external lock.
+ * @name: The tree name
+ * @__flags: The maple tree flags
+ * @__lock: The external lock
+ */
+#ifdef CONFIG_LOCKDEP
+#define MTREE_INIT_EXT(name, __flags, __lock) { \
+ .ma_external_lock = &(__lock).dep_map, \
+ .ma_flags = (__flags), \
+ .ma_root = NULL, \
+}
+#else
+#define MTREE_INIT_EXT(name, __flags, __lock) MTREE_INIT(name, __flags)
+#endif
+
+#define DEFINE_MTREE(name) \
+ struct maple_tree name = MTREE_INIT(name, 0)
+
+#define mtree_lock(mt) spin_lock((&(mt)->ma_lock))
+#define mtree_unlock(mt) spin_unlock((&(mt)->ma_lock))
+
+/*
+ * The Maple Tree squeezes various bits in at various points which aren't
+ * necessarily obvious. Usually, this is done by observing that pointers are
+ * N-byte aligned and thus the bottom log_2(N) bits are available for use. We
+ * don't use the high bits of pointers to store additional information because
+ * we don't know what bits are unused on any given architecture.
+ *
+ * Nodes are 256 bytes in size and are also aligned to 256 bytes, giving us 8
+ * low bits for our own purposes. Nodes are currently of 4 types:
+ * 1. Single pointer (Range is 0-0)
+ * 2. Non-leaf Allocation Range nodes
+ * 3. Non-leaf Range nodes
+ * 4. Leaf Range nodes All nodes consist of a number of node slots,
+ * pivots, and a parent pointer.
+ */
+
+struct maple_node {
+ union {
+ struct {
+ struct maple_pnode *parent;
+ void __rcu *slot[MAPLE_NODE_SLOTS];
+ };
+ struct {
+ void *pad;
+ struct rcu_head rcu;
+ struct maple_enode *piv_parent;
+ unsigned char parent_slot;
+ enum maple_type type;
+ unsigned char slot_len;
+ unsigned int ma_flags;
+ };
+ struct maple_range_64 mr64;
+ struct maple_arange_64 ma64;
+ struct maple_alloc alloc;
+ };
+};
+
+/*
+ * More complicated stores can cause two nodes to become one or three and
+ * potentially alter the height of the tree. Either half of the tree may need
+ * to be rebalanced against the other. The ma_topiary struct is used to track
+ * which nodes have been 'cut' from the tree so that the change can be done
+ * safely at a later date. This is done to support RCU.
+ */
+struct ma_topiary {
+ struct maple_enode *head;
+ struct maple_enode *tail;
+ struct maple_tree *mtree;
+};
+
+void *mtree_load(struct maple_tree *mt, unsigned long index);
+
+int mtree_insert(struct maple_tree *mt, unsigned long index,
+ void *entry, gfp_t gfp);
+int mtree_insert_range(struct maple_tree *mt, unsigned long first,
+ unsigned long last, void *entry, gfp_t gfp);
+int mtree_alloc_range(struct maple_tree *mt, unsigned long *startp,
+ void *entry, unsigned long size, unsigned long min,
+ unsigned long max, gfp_t gfp);
+int mtree_alloc_rrange(struct maple_tree *mt, unsigned long *startp,
+ void *entry, unsigned long size, unsigned long min,
+ unsigned long max, gfp_t gfp);
+
+int mtree_store_range(struct maple_tree *mt, unsigned long first,
+ unsigned long last, void *entry, gfp_t gfp);
+int mtree_store(struct maple_tree *mt, unsigned long index,
+ void *entry, gfp_t gfp);
+void *mtree_erase(struct maple_tree *mt, unsigned long index);
+
+void mtree_destroy(struct maple_tree *mt);
+void __mt_destroy(struct maple_tree *mt);
+
+/**
+ * mtree_empty() - Determine if a tree has any present entries.
+ * @mt: Maple Tree.
+ *
+ * Context: Any context.
+ * Return: %true if the tree contains only NULL pointers.
+ */
+static inline bool mtree_empty(const struct maple_tree *mt)
+{
+ return mt->ma_root == NULL;
+}
+
+/* Advanced API */
+
+/*
+ * The maple state is defined in the struct ma_state and is used to keep track
+ * of information during operations, and even between operations when using the
+ * advanced API.
+ *
+ * If state->node has bit 0 set then it references a tree location which is not
+ * a node (eg the root). If bit 1 is set, the rest of the bits are a negative
+ * errno. Bit 2 (the 'unallocated slots' bit) is clear. Bits 3-6 indicate the
+ * node type.
+ *
+ * state->alloc either has a request number of nodes or an allocated node. If
+ * stat->alloc has a requested number of nodes, the first bit will be set (0x1)
+ * and the remaining bits are the value. If state->alloc is a node, then the
+ * node will be of type maple_alloc. maple_alloc has MAPLE_NODE_SLOTS - 1 for
+ * storing more allocated nodes, a total number of nodes allocated, and the
+ * node_count in this node. node_count is the number of allocated nodes in this
+ * node. The scaling beyond MAPLE_NODE_SLOTS - 1 is handled by storing further
+ * nodes into state->alloc->slot[0]'s node. Nodes are taken from state->alloc
+ * by removing a node from the state->alloc node until state->alloc->node_count
+ * is 1, when state->alloc is returned and the state->alloc->slot[0] is promoted
+ * to state->alloc. Nodes are pushed onto state->alloc by putting the current
+ * state->alloc into the pushed node's slot[0].
+ *
+ * The state also contains the implied min/max of the state->node, the depth of
+ * this search, and the offset. The implied min/max are either from the parent
+ * node or are 0-oo for the root node. The depth is incremented or decremented
+ * every time a node is walked down or up. The offset is the slot/pivot of
+ * interest in the node - either for reading or writing.
+ *
+ * When returning a value the maple state index and last respectively contain
+ * the start and end of the range for the entry. Ranges are inclusive in the
+ * Maple Tree.
+ */
+struct ma_state {
+ struct maple_tree *tree; /* The tree we're operating in */
+ unsigned long index; /* The index we're operating on - range start */
+ unsigned long last; /* The last index we're operating on - range end */
+ struct maple_enode *node; /* The node containing this entry */
+ unsigned long min; /* The minimum index of this node - implied pivot min */
+ unsigned long max; /* The maximum index of this node - implied pivot max */
+ struct maple_alloc *alloc; /* Allocated nodes for this operation */
+ unsigned char depth; /* depth of tree descent during write */
+ unsigned char offset;
+ unsigned char mas_flags;
+};
+
+struct ma_wr_state {
+ struct ma_state *mas;
+ struct maple_node *node; /* Decoded mas->node */
+ unsigned long r_min; /* range min */
+ unsigned long r_max; /* range max */
+ enum maple_type type; /* mas->node type */
+ unsigned char offset_end; /* The offset where the write ends */
+ unsigned char node_end; /* mas->node end */
+ unsigned long *pivots; /* mas->node->pivots pointer */
+ unsigned long end_piv; /* The pivot at the offset end */
+ void __rcu **slots; /* mas->node->slots pointer */
+ void *entry; /* The entry to write */
+ void *content; /* The existing entry that is being overwritten */
+};
+
+#define mas_lock(mas) spin_lock(&((mas)->tree->ma_lock))
+#define mas_unlock(mas) spin_unlock(&((mas)->tree->ma_lock))
+
+
+/*
+ * Special values for ma_state.node.
+ * MAS_START means we have not searched the tree.
+ * MAS_ROOT means we have searched the tree and the entry we found lives in
+ * the root of the tree (ie it has index 0, length 1 and is the only entry in
+ * the tree).
+ * MAS_NONE means we have searched the tree and there is no node in the
+ * tree for this entry. For example, we searched for index 1 in an empty
+ * tree. Or we have a tree which points to a full leaf node and we
+ * searched for an entry which is larger than can be contained in that
+ * leaf node.
+ * MA_ERROR represents an errno. After dropping the lock and attempting
+ * to resolve the error, the walk would have to be restarted from the
+ * top of the tree as the tree may have been modified.
+ */
+#define MAS_START ((struct maple_enode *)1UL)
+#define MAS_ROOT ((struct maple_enode *)5UL)
+#define MAS_NONE ((struct maple_enode *)9UL)
+#define MAS_PAUSE ((struct maple_enode *)17UL)
+#define MA_ERROR(err) \
+ ((struct maple_enode *)(((unsigned long)err << 2) | 2UL))
+
+#define MA_STATE(name, mt, first, end) \
+ struct ma_state name = { \
+ .tree = mt, \
+ .index = first, \
+ .last = end, \
+ .node = MAS_START, \
+ .min = 0, \
+ .max = ULONG_MAX, \
+ .alloc = NULL, \
+ }
+
+#define MA_WR_STATE(name, ma_state, wr_entry) \
+ struct ma_wr_state name = { \
+ .mas = ma_state, \
+ .content = NULL, \
+ .entry = wr_entry, \
+ }
+
+#define MA_TOPIARY(name, tree) \
+ struct ma_topiary name = { \
+ .head = NULL, \
+ .tail = NULL, \
+ .mtree = tree, \
+ }
+
+void *mas_walk(struct ma_state *mas);
+void *mas_store(struct ma_state *mas, void *entry);
+void *mas_erase(struct ma_state *mas);
+int mas_store_gfp(struct ma_state *mas, void *entry, gfp_t gfp);
+void mas_store_prealloc(struct ma_state *mas, void *entry);
+void *mas_find(struct ma_state *mas, unsigned long max);
+void *mas_find_rev(struct ma_state *mas, unsigned long min);
+int mas_preallocate(struct ma_state *mas, void *entry, gfp_t gfp);
+bool mas_is_err(struct ma_state *mas);
+
+bool mas_nomem(struct ma_state *mas, gfp_t gfp);
+void mas_pause(struct ma_state *mas);
+void maple_tree_init(void);
+void mas_destroy(struct ma_state *mas);
+int mas_expected_entries(struct ma_state *mas, unsigned long nr_entries);
+
+void *mas_prev(struct ma_state *mas, unsigned long min);
+void *mas_next(struct ma_state *mas, unsigned long max);
+
+int mas_empty_area(struct ma_state *mas, unsigned long min, unsigned long max,
+ unsigned long size);
+
+/* Checks if a mas has not found anything */
+static inline bool mas_is_none(struct ma_state *mas)
+{
+ return mas->node == MAS_NONE;
+}
+
+/* Checks if a mas has been paused */
+static inline bool mas_is_paused(struct ma_state *mas)
+{
+ return mas->node == MAS_PAUSE;
+}
+
+void mas_dup_tree(struct ma_state *oldmas, struct ma_state *mas);
+void mas_dup_store(struct ma_state *mas, void *entry);
+
+/*
+ * This finds an empty area from the highest address to the lowest.
+ * AKA "Topdown" version,
+ */
+int mas_empty_area_rev(struct ma_state *mas, unsigned long min,
+ unsigned long max, unsigned long size);
+/**
+ * mas_reset() - Reset a Maple Tree operation state.
+ * @mas: Maple Tree operation state.
+ *
+ * Resets the error or walk state of the @mas so future walks of the
+ * array will start from the root. Use this if you have dropped the
+ * lock and want to reuse the ma_state.
+ *
+ * Context: Any context.
+ */
+static inline void mas_reset(struct ma_state *mas)
+{
+ mas->node = MAS_START;
+}
+
+/**
+ * mas_for_each() - Iterate over a range of the maple tree.
+ * @__mas: Maple Tree operation state (maple_state)
+ * @__entry: Entry retrieved from the tree
+ * @__max: maximum index to retrieve from the tree
+ *
+ * When returned, mas->index and mas->last will hold the entire range for the
+ * entry.
+ *
+ * Note: may return the zero entry.
+ *
+ */
+#define mas_for_each(__mas, __entry, __max) \
+ while (((__entry) = mas_find((__mas), (__max))) != NULL)
+
+
+/**
+ * mas_set_range() - Set up Maple Tree operation state for a different index.
+ * @mas: Maple Tree operation state.
+ * @start: New start of range in the Maple Tree.
+ * @last: New end of range in the Maple Tree.
+ *
+ * Move the operation state to refer to a different range. This will
+ * have the effect of starting a walk from the top; see mas_next()
+ * to move to an adjacent index.
+ */
+static inline
+void mas_set_range(struct ma_state *mas, unsigned long start, unsigned long last)
+{
+ mas->index = start;
+ mas->last = last;
+ mas->node = MAS_START;
+}
+
+/**
+ * mas_set() - Set up Maple Tree operation state for a different index.
+ * @mas: Maple Tree operation state.
+ * @index: New index into the Maple Tree.
+ *
+ * Move the operation state to refer to a different index. This will
+ * have the effect of starting a walk from the top; see mas_next()
+ * to move to an adjacent index.
+ */
+static inline void mas_set(struct ma_state *mas, unsigned long index)
+{
+
+ mas_set_range(mas, index, index);
+}
+
+static inline bool mt_external_lock(const struct maple_tree *mt)
+{
+ return (mt->ma_flags & MT_FLAGS_LOCK_MASK) == MT_FLAGS_LOCK_EXTERN;
+}
+
+/**
+ * mt_init_flags() - Initialise an empty maple tree with flags.
+ * @mt: Maple Tree
+ * @flags: maple tree flags.
+ *
+ * If you need to initialise a Maple Tree with special flags (eg, an
+ * allocation tree), use this function.
+ *
+ * Context: Any context.
+ */
+static inline void mt_init_flags(struct maple_tree *mt, unsigned int flags)
+{
+ mt->ma_flags = flags;
+ if (!mt_external_lock(mt))
+ spin_lock_init(&mt->ma_lock);
+ rcu_assign_pointer(mt->ma_root, NULL);
+}
+
+/**
+ * mt_init() - Initialise an empty maple tree.
+ * @mt: Maple Tree
+ *
+ * An empty Maple Tree.
+ *
+ * Context: Any context.
+ */
+static inline void mt_init(struct maple_tree *mt)
+{
+ mt_init_flags(mt, 0);
+}
+
+static inline bool mt_in_rcu(struct maple_tree *mt)
+{
+#ifdef CONFIG_MAPLE_RCU_DISABLED
+ return false;
+#endif
+ return mt->ma_flags & MT_FLAGS_USE_RCU;
+}
+
+/**
+ * mt_clear_in_rcu() - Switch the tree to non-RCU mode.
+ * @mt: The Maple Tree
+ */
+static inline void mt_clear_in_rcu(struct maple_tree *mt)
+{
+ if (!mt_in_rcu(mt))
+ return;
+
+ if (mt_external_lock(mt)) {
+ BUG_ON(!mt_lock_is_held(mt));
+ mt->ma_flags &= ~MT_FLAGS_USE_RCU;
+ } else {
+ mtree_lock(mt);
+ mt->ma_flags &= ~MT_FLAGS_USE_RCU;
+ mtree_unlock(mt);
+ }
+}
+
+/**
+ * mt_set_in_rcu() - Switch the tree to RCU safe mode.
+ * @mt: The Maple Tree
+ */
+static inline void mt_set_in_rcu(struct maple_tree *mt)
+{
+ if (mt_in_rcu(mt))
+ return;
+
+ if (mt_external_lock(mt)) {
+ BUG_ON(!mt_lock_is_held(mt));
+ mt->ma_flags |= MT_FLAGS_USE_RCU;
+ } else {
+ mtree_lock(mt);
+ mt->ma_flags |= MT_FLAGS_USE_RCU;
+ mtree_unlock(mt);
+ }
+}
+
+static inline unsigned int mt_height(const struct maple_tree *mt)
+
+{
+ return (mt->ma_flags & MT_FLAGS_HEIGHT_MASK) >> MT_FLAGS_HEIGHT_OFFSET;
+}
+
+void *mt_find(struct maple_tree *mt, unsigned long *index, unsigned long max);
+void *mt_find_after(struct maple_tree *mt, unsigned long *index,
+ unsigned long max);
+void *mt_prev(struct maple_tree *mt, unsigned long index, unsigned long min);
+void *mt_next(struct maple_tree *mt, unsigned long index, unsigned long max);
+
+/**
+ * mt_for_each - Iterate over each entry starting at index until max.
+ * @__tree: The Maple Tree
+ * @__entry: The current entry
+ * @__index: The index to update to track the location in the tree
+ * @__max: The maximum limit for @index
+ *
+ * Note: Will not return the zero entry.
+ */
+#define mt_for_each(__tree, __entry, __index, __max) \
+ for (__entry = mt_find(__tree, &(__index), __max); \
+ __entry; __entry = mt_find_after(__tree, &(__index), __max))
+
+
+#ifdef CONFIG_DEBUG_MAPLE_TREE
+extern atomic_t maple_tree_tests_run;
+extern atomic_t maple_tree_tests_passed;
+
+void mt_dump(const struct maple_tree *mt);
+void mt_validate(struct maple_tree *mt);
+void mt_cache_shrink(void);
+#define MT_BUG_ON(__tree, __x) do { \
+ atomic_inc(&maple_tree_tests_run); \
+ if (__x) { \
+ pr_info("BUG at %s:%d (%u)\n", \
+ __func__, __LINE__, __x); \
+ mt_dump(__tree); \
+ pr_info("Pass: %u Run:%u\n", \
+ atomic_read(&maple_tree_tests_passed), \
+ atomic_read(&maple_tree_tests_run)); \
+ dump_stack(); \
+ } else { \
+ atomic_inc(&maple_tree_tests_passed); \
+ } \
+} while (0)
+#else
+#define MT_BUG_ON(__tree, __x) BUG_ON(__x)
+#endif /* CONFIG_DEBUG_MAPLE_TREE */
+
+#endif /*_LINUX_MAPLE_TREE_H */