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- // SPDX-License-Identifier: GPL-2.0+
- /*
- * XArray implementation
- * Copyright (c) 2017-2018 Microsoft Corporation
- * Copyright (c) 2018-2020 Oracle
- * Author: Matthew Wilcox <willy@infradead.org>
- */
- #include <linux/bitmap.h>
- #include <linux/export.h>
- #include <linux/list.h>
- #include <linux/slab.h>
- #include <linux/xarray.h>
- /*
- * Coding conventions in this file:
- *
- * @xa is used to refer to the entire xarray.
- * @xas is the 'xarray operation state'. It may be either a pointer to
- * an xa_state, or an xa_state stored on the stack. This is an unfortunate
- * ambiguity.
- * @index is the index of the entry being operated on
- * @mark is an xa_mark_t; a small number indicating one of the mark bits.
- * @node refers to an xa_node; usually the primary one being operated on by
- * this function.
- * @offset is the index into the slots array inside an xa_node.
- * @parent refers to the @xa_node closer to the head than @node.
- * @entry refers to something stored in a slot in the xarray
- */
- static inline unsigned int xa_lock_type(const struct xarray *xa)
- {
- return (__force unsigned int)xa->xa_flags & 3;
- }
- static inline void xas_lock_type(struct xa_state *xas, unsigned int lock_type)
- {
- if (lock_type == XA_LOCK_IRQ)
- xas_lock_irq(xas);
- else if (lock_type == XA_LOCK_BH)
- xas_lock_bh(xas);
- else
- xas_lock(xas);
- }
- static inline void xas_unlock_type(struct xa_state *xas, unsigned int lock_type)
- {
- if (lock_type == XA_LOCK_IRQ)
- xas_unlock_irq(xas);
- else if (lock_type == XA_LOCK_BH)
- xas_unlock_bh(xas);
- else
- xas_unlock(xas);
- }
- static inline bool xa_track_free(const struct xarray *xa)
- {
- return xa->xa_flags & XA_FLAGS_TRACK_FREE;
- }
- static inline bool xa_zero_busy(const struct xarray *xa)
- {
- return xa->xa_flags & XA_FLAGS_ZERO_BUSY;
- }
- static inline void xa_mark_set(struct xarray *xa, xa_mark_t mark)
- {
- if (!(xa->xa_flags & XA_FLAGS_MARK(mark)))
- xa->xa_flags |= XA_FLAGS_MARK(mark);
- }
- static inline void xa_mark_clear(struct xarray *xa, xa_mark_t mark)
- {
- if (xa->xa_flags & XA_FLAGS_MARK(mark))
- xa->xa_flags &= ~(XA_FLAGS_MARK(mark));
- }
- static inline unsigned long *node_marks(struct xa_node *node, xa_mark_t mark)
- {
- return node->marks[(__force unsigned)mark];
- }
- static inline bool node_get_mark(struct xa_node *node,
- unsigned int offset, xa_mark_t mark)
- {
- return test_bit(offset, node_marks(node, mark));
- }
- /* returns true if the bit was set */
- static inline bool node_set_mark(struct xa_node *node, unsigned int offset,
- xa_mark_t mark)
- {
- return __test_and_set_bit(offset, node_marks(node, mark));
- }
- /* returns true if the bit was set */
- static inline bool node_clear_mark(struct xa_node *node, unsigned int offset,
- xa_mark_t mark)
- {
- return __test_and_clear_bit(offset, node_marks(node, mark));
- }
- static inline bool node_any_mark(struct xa_node *node, xa_mark_t mark)
- {
- return !bitmap_empty(node_marks(node, mark), XA_CHUNK_SIZE);
- }
- static inline void node_mark_all(struct xa_node *node, xa_mark_t mark)
- {
- bitmap_fill(node_marks(node, mark), XA_CHUNK_SIZE);
- }
- #define mark_inc(mark) do { \
- mark = (__force xa_mark_t)((__force unsigned)(mark) + 1); \
- } while (0)
- /*
- * xas_squash_marks() - Merge all marks to the first entry
- * @xas: Array operation state.
- *
- * Set a mark on the first entry if any entry has it set. Clear marks on
- * all sibling entries.
- */
- static void xas_squash_marks(const struct xa_state *xas)
- {
- unsigned int mark = 0;
- unsigned int limit = xas->xa_offset + xas->xa_sibs + 1;
- if (!xas->xa_sibs)
- return;
- do {
- unsigned long *marks = xas->xa_node->marks[mark];
- if (find_next_bit(marks, limit, xas->xa_offset + 1) == limit)
- continue;
- __set_bit(xas->xa_offset, marks);
- bitmap_clear(marks, xas->xa_offset + 1, xas->xa_sibs);
- } while (mark++ != (__force unsigned)XA_MARK_MAX);
- }
- /* extracts the offset within this node from the index */
- static unsigned int get_offset(unsigned long index, struct xa_node *node)
- {
- return (index >> node->shift) & XA_CHUNK_MASK;
- }
- static void xas_set_offset(struct xa_state *xas)
- {
- xas->xa_offset = get_offset(xas->xa_index, xas->xa_node);
- }
- /* move the index either forwards (find) or backwards (sibling slot) */
- static void xas_move_index(struct xa_state *xas, unsigned long offset)
- {
- unsigned int shift = xas->xa_node->shift;
- xas->xa_index &= ~XA_CHUNK_MASK << shift;
- xas->xa_index += offset << shift;
- }
- static void xas_advance(struct xa_state *xas)
- {
- xas->xa_offset++;
- xas_move_index(xas, xas->xa_offset);
- }
- static void *set_bounds(struct xa_state *xas)
- {
- xas->xa_node = XAS_BOUNDS;
- return NULL;
- }
- /*
- * Starts a walk. If the @xas is already valid, we assume that it's on
- * the right path and just return where we've got to. If we're in an
- * error state, return NULL. If the index is outside the current scope
- * of the xarray, return NULL without changing @xas->xa_node. Otherwise
- * set @xas->xa_node to NULL and return the current head of the array.
- */
- static void *xas_start(struct xa_state *xas)
- {
- void *entry;
- if (xas_valid(xas))
- return xas_reload(xas);
- if (xas_error(xas))
- return NULL;
- entry = xa_head(xas->xa);
- if (!xa_is_node(entry)) {
- if (xas->xa_index)
- return set_bounds(xas);
- } else {
- if ((xas->xa_index >> xa_to_node(entry)->shift) > XA_CHUNK_MASK)
- return set_bounds(xas);
- }
- xas->xa_node = NULL;
- return entry;
- }
- static void *xas_descend(struct xa_state *xas, struct xa_node *node)
- {
- unsigned int offset = get_offset(xas->xa_index, node);
- void *entry = xa_entry(xas->xa, node, offset);
- xas->xa_node = node;
- if (xa_is_sibling(entry)) {
- offset = xa_to_sibling(entry);
- entry = xa_entry(xas->xa, node, offset);
- }
- xas->xa_offset = offset;
- return entry;
- }
- /**
- * xas_load() - Load an entry from the XArray (advanced).
- * @xas: XArray operation state.
- *
- * Usually walks the @xas to the appropriate state to load the entry
- * stored at xa_index. However, it will do nothing and return %NULL if
- * @xas is in an error state. xas_load() will never expand the tree.
- *
- * If the xa_state is set up to operate on a multi-index entry, xas_load()
- * may return %NULL or an internal entry, even if there are entries
- * present within the range specified by @xas.
- *
- * Context: Any context. The caller should hold the xa_lock or the RCU lock.
- * Return: Usually an entry in the XArray, but see description for exceptions.
- */
- void *xas_load(struct xa_state *xas)
- {
- void *entry = xas_start(xas);
- while (xa_is_node(entry)) {
- struct xa_node *node = xa_to_node(entry);
- if (xas->xa_shift > node->shift)
- break;
- entry = xas_descend(xas, node);
- if (node->shift == 0)
- break;
- }
- return entry;
- }
- EXPORT_SYMBOL_GPL(xas_load);
- /* Move the radix tree node cache here */
- extern struct kmem_cache *radix_tree_node_cachep;
- extern void radix_tree_node_rcu_free(struct rcu_head *head);
- #define XA_RCU_FREE ((struct xarray *)1)
- static void xa_node_free(struct xa_node *node)
- {
- XA_NODE_BUG_ON(node, !list_empty(&node->private_list));
- node->array = XA_RCU_FREE;
- call_rcu(&node->rcu_head, radix_tree_node_rcu_free);
- }
- /*
- * xas_destroy() - Free any resources allocated during the XArray operation.
- * @xas: XArray operation state.
- *
- * This function is now internal-only.
- */
- static void xas_destroy(struct xa_state *xas)
- {
- struct xa_node *next, *node = xas->xa_alloc;
- while (node) {
- XA_NODE_BUG_ON(node, !list_empty(&node->private_list));
- next = rcu_dereference_raw(node->parent);
- radix_tree_node_rcu_free(&node->rcu_head);
- xas->xa_alloc = node = next;
- }
- }
- /**
- * xas_nomem() - Allocate memory if needed.
- * @xas: XArray operation state.
- * @gfp: Memory allocation flags.
- *
- * If we need to add new nodes to the XArray, we try to allocate memory
- * with GFP_NOWAIT while holding the lock, which will usually succeed.
- * If it fails, @xas is flagged as needing memory to continue. The caller
- * should drop the lock and call xas_nomem(). If xas_nomem() succeeds,
- * the caller should retry the operation.
- *
- * Forward progress is guaranteed as one node is allocated here and
- * stored in the xa_state where it will be found by xas_alloc(). More
- * nodes will likely be found in the slab allocator, but we do not tie
- * them up here.
- *
- * Return: true if memory was needed, and was successfully allocated.
- */
- bool xas_nomem(struct xa_state *xas, gfp_t gfp)
- {
- if (xas->xa_node != XA_ERROR(-ENOMEM)) {
- xas_destroy(xas);
- return false;
- }
- if (xas->xa->xa_flags & XA_FLAGS_ACCOUNT)
- gfp |= __GFP_ACCOUNT;
- xas->xa_alloc = kmem_cache_alloc(radix_tree_node_cachep, gfp);
- if (!xas->xa_alloc)
- return false;
- xas->xa_alloc->parent = NULL;
- XA_NODE_BUG_ON(xas->xa_alloc, !list_empty(&xas->xa_alloc->private_list));
- xas->xa_node = XAS_RESTART;
- return true;
- }
- EXPORT_SYMBOL_GPL(xas_nomem);
- /*
- * __xas_nomem() - Drop locks and allocate memory if needed.
- * @xas: XArray operation state.
- * @gfp: Memory allocation flags.
- *
- * Internal variant of xas_nomem().
- *
- * Return: true if memory was needed, and was successfully allocated.
- */
- static bool __xas_nomem(struct xa_state *xas, gfp_t gfp)
- __must_hold(xas->xa->xa_lock)
- {
- unsigned int lock_type = xa_lock_type(xas->xa);
- if (xas->xa_node != XA_ERROR(-ENOMEM)) {
- xas_destroy(xas);
- return false;
- }
- if (xas->xa->xa_flags & XA_FLAGS_ACCOUNT)
- gfp |= __GFP_ACCOUNT;
- if (gfpflags_allow_blocking(gfp)) {
- xas_unlock_type(xas, lock_type);
- xas->xa_alloc = kmem_cache_alloc(radix_tree_node_cachep, gfp);
- xas_lock_type(xas, lock_type);
- } else {
- xas->xa_alloc = kmem_cache_alloc(radix_tree_node_cachep, gfp);
- }
- if (!xas->xa_alloc)
- return false;
- xas->xa_alloc->parent = NULL;
- XA_NODE_BUG_ON(xas->xa_alloc, !list_empty(&xas->xa_alloc->private_list));
- xas->xa_node = XAS_RESTART;
- return true;
- }
- static void xas_update(struct xa_state *xas, struct xa_node *node)
- {
- if (xas->xa_update)
- xas->xa_update(node);
- else
- XA_NODE_BUG_ON(node, !list_empty(&node->private_list));
- }
- static void *xas_alloc(struct xa_state *xas, unsigned int shift)
- {
- struct xa_node *parent = xas->xa_node;
- struct xa_node *node = xas->xa_alloc;
- if (xas_invalid(xas))
- return NULL;
- if (node) {
- xas->xa_alloc = NULL;
- } else {
- gfp_t gfp = GFP_NOWAIT | __GFP_NOWARN;
- if (xas->xa->xa_flags & XA_FLAGS_ACCOUNT)
- gfp |= __GFP_ACCOUNT;
- node = kmem_cache_alloc(radix_tree_node_cachep, gfp);
- if (!node) {
- xas_set_err(xas, -ENOMEM);
- return NULL;
- }
- }
- if (parent) {
- node->offset = xas->xa_offset;
- parent->count++;
- XA_NODE_BUG_ON(node, parent->count > XA_CHUNK_SIZE);
- xas_update(xas, parent);
- }
- XA_NODE_BUG_ON(node, shift > BITS_PER_LONG);
- XA_NODE_BUG_ON(node, !list_empty(&node->private_list));
- node->shift = shift;
- node->count = 0;
- node->nr_values = 0;
- RCU_INIT_POINTER(node->parent, xas->xa_node);
- node->array = xas->xa;
- return node;
- }
- #ifdef CONFIG_XARRAY_MULTI
- /* Returns the number of indices covered by a given xa_state */
- static unsigned long xas_size(const struct xa_state *xas)
- {
- return (xas->xa_sibs + 1UL) << xas->xa_shift;
- }
- #endif
- /*
- * Use this to calculate the maximum index that will need to be created
- * in order to add the entry described by @xas. Because we cannot store a
- * multi-index entry at index 0, the calculation is a little more complex
- * than you might expect.
- */
- static unsigned long xas_max(struct xa_state *xas)
- {
- unsigned long max = xas->xa_index;
- #ifdef CONFIG_XARRAY_MULTI
- if (xas->xa_shift || xas->xa_sibs) {
- unsigned long mask = xas_size(xas) - 1;
- max |= mask;
- if (mask == max)
- max++;
- }
- #endif
- return max;
- }
- /* The maximum index that can be contained in the array without expanding it */
- static unsigned long max_index(void *entry)
- {
- if (!xa_is_node(entry))
- return 0;
- return (XA_CHUNK_SIZE << xa_to_node(entry)->shift) - 1;
- }
- static void xas_shrink(struct xa_state *xas)
- {
- struct xarray *xa = xas->xa;
- struct xa_node *node = xas->xa_node;
- for (;;) {
- void *entry;
- XA_NODE_BUG_ON(node, node->count > XA_CHUNK_SIZE);
- if (node->count != 1)
- break;
- entry = xa_entry_locked(xa, node, 0);
- if (!entry)
- break;
- if (!xa_is_node(entry) && node->shift)
- break;
- if (xa_is_zero(entry) && xa_zero_busy(xa))
- entry = NULL;
- xas->xa_node = XAS_BOUNDS;
- RCU_INIT_POINTER(xa->xa_head, entry);
- if (xa_track_free(xa) && !node_get_mark(node, 0, XA_FREE_MARK))
- xa_mark_clear(xa, XA_FREE_MARK);
- node->count = 0;
- node->nr_values = 0;
- if (!xa_is_node(entry))
- RCU_INIT_POINTER(node->slots[0], XA_RETRY_ENTRY);
- xas_update(xas, node);
- xa_node_free(node);
- if (!xa_is_node(entry))
- break;
- node = xa_to_node(entry);
- node->parent = NULL;
- }
- }
- /*
- * xas_delete_node() - Attempt to delete an xa_node
- * @xas: Array operation state.
- *
- * Attempts to delete the @xas->xa_node. This will fail if xa->node has
- * a non-zero reference count.
- */
- static void xas_delete_node(struct xa_state *xas)
- {
- struct xa_node *node = xas->xa_node;
- for (;;) {
- struct xa_node *parent;
- XA_NODE_BUG_ON(node, node->count > XA_CHUNK_SIZE);
- if (node->count)
- break;
- parent = xa_parent_locked(xas->xa, node);
- xas->xa_node = parent;
- xas->xa_offset = node->offset;
- xa_node_free(node);
- if (!parent) {
- xas->xa->xa_head = NULL;
- xas->xa_node = XAS_BOUNDS;
- return;
- }
- parent->slots[xas->xa_offset] = NULL;
- parent->count--;
- XA_NODE_BUG_ON(parent, parent->count > XA_CHUNK_SIZE);
- node = parent;
- xas_update(xas, node);
- }
- if (!node->parent)
- xas_shrink(xas);
- }
- /**
- * xas_free_nodes() - Free this node and all nodes that it references
- * @xas: Array operation state.
- * @top: Node to free
- *
- * This node has been removed from the tree. We must now free it and all
- * of its subnodes. There may be RCU walkers with references into the tree,
- * so we must replace all entries with retry markers.
- */
- static void xas_free_nodes(struct xa_state *xas, struct xa_node *top)
- {
- unsigned int offset = 0;
- struct xa_node *node = top;
- for (;;) {
- void *entry = xa_entry_locked(xas->xa, node, offset);
- if (node->shift && xa_is_node(entry)) {
- node = xa_to_node(entry);
- offset = 0;
- continue;
- }
- if (entry)
- RCU_INIT_POINTER(node->slots[offset], XA_RETRY_ENTRY);
- offset++;
- while (offset == XA_CHUNK_SIZE) {
- struct xa_node *parent;
- parent = xa_parent_locked(xas->xa, node);
- offset = node->offset + 1;
- node->count = 0;
- node->nr_values = 0;
- xas_update(xas, node);
- xa_node_free(node);
- if (node == top)
- return;
- node = parent;
- }
- }
- }
- /*
- * xas_expand adds nodes to the head of the tree until it has reached
- * sufficient height to be able to contain @xas->xa_index
- */
- static int xas_expand(struct xa_state *xas, void *head)
- {
- struct xarray *xa = xas->xa;
- struct xa_node *node = NULL;
- unsigned int shift = 0;
- unsigned long max = xas_max(xas);
- if (!head) {
- if (max == 0)
- return 0;
- while ((max >> shift) >= XA_CHUNK_SIZE)
- shift += XA_CHUNK_SHIFT;
- return shift + XA_CHUNK_SHIFT;
- } else if (xa_is_node(head)) {
- node = xa_to_node(head);
- shift = node->shift + XA_CHUNK_SHIFT;
- }
- xas->xa_node = NULL;
- while (max > max_index(head)) {
- xa_mark_t mark = 0;
- XA_NODE_BUG_ON(node, shift > BITS_PER_LONG);
- node = xas_alloc(xas, shift);
- if (!node)
- return -ENOMEM;
- node->count = 1;
- if (xa_is_value(head))
- node->nr_values = 1;
- RCU_INIT_POINTER(node->slots[0], head);
- /* Propagate the aggregated mark info to the new child */
- for (;;) {
- if (xa_track_free(xa) && mark == XA_FREE_MARK) {
- node_mark_all(node, XA_FREE_MARK);
- if (!xa_marked(xa, XA_FREE_MARK)) {
- node_clear_mark(node, 0, XA_FREE_MARK);
- xa_mark_set(xa, XA_FREE_MARK);
- }
- } else if (xa_marked(xa, mark)) {
- node_set_mark(node, 0, mark);
- }
- if (mark == XA_MARK_MAX)
- break;
- mark_inc(mark);
- }
- /*
- * Now that the new node is fully initialised, we can add
- * it to the tree
- */
- if (xa_is_node(head)) {
- xa_to_node(head)->offset = 0;
- rcu_assign_pointer(xa_to_node(head)->parent, node);
- }
- head = xa_mk_node(node);
- rcu_assign_pointer(xa->xa_head, head);
- xas_update(xas, node);
- shift += XA_CHUNK_SHIFT;
- }
- xas->xa_node = node;
- return shift;
- }
- /*
- * xas_create() - Create a slot to store an entry in.
- * @xas: XArray operation state.
- * @allow_root: %true if we can store the entry in the root directly
- *
- * Most users will not need to call this function directly, as it is called
- * by xas_store(). It is useful for doing conditional store operations
- * (see the xa_cmpxchg() implementation for an example).
- *
- * Return: If the slot already existed, returns the contents of this slot.
- * If the slot was newly created, returns %NULL. If it failed to create the
- * slot, returns %NULL and indicates the error in @xas.
- */
- static void *xas_create(struct xa_state *xas, bool allow_root)
- {
- struct xarray *xa = xas->xa;
- void *entry;
- void __rcu **slot;
- struct xa_node *node = xas->xa_node;
- int shift;
- unsigned int order = xas->xa_shift;
- if (xas_top(node)) {
- entry = xa_head_locked(xa);
- xas->xa_node = NULL;
- if (!entry && xa_zero_busy(xa))
- entry = XA_ZERO_ENTRY;
- shift = xas_expand(xas, entry);
- if (shift < 0)
- return NULL;
- if (!shift && !allow_root)
- shift = XA_CHUNK_SHIFT;
- entry = xa_head_locked(xa);
- slot = &xa->xa_head;
- } else if (xas_error(xas)) {
- return NULL;
- } else if (node) {
- unsigned int offset = xas->xa_offset;
- shift = node->shift;
- entry = xa_entry_locked(xa, node, offset);
- slot = &node->slots[offset];
- } else {
- shift = 0;
- entry = xa_head_locked(xa);
- slot = &xa->xa_head;
- }
- while (shift > order) {
- shift -= XA_CHUNK_SHIFT;
- if (!entry) {
- node = xas_alloc(xas, shift);
- if (!node)
- break;
- if (xa_track_free(xa))
- node_mark_all(node, XA_FREE_MARK);
- rcu_assign_pointer(*slot, xa_mk_node(node));
- } else if (xa_is_node(entry)) {
- node = xa_to_node(entry);
- } else {
- break;
- }
- entry = xas_descend(xas, node);
- slot = &node->slots[xas->xa_offset];
- }
- return entry;
- }
- /**
- * xas_create_range() - Ensure that stores to this range will succeed
- * @xas: XArray operation state.
- *
- * Creates all of the slots in the range covered by @xas. Sets @xas to
- * create single-index entries and positions it at the beginning of the
- * range. This is for the benefit of users which have not yet been
- * converted to use multi-index entries.
- */
- void xas_create_range(struct xa_state *xas)
- {
- unsigned long index = xas->xa_index;
- unsigned char shift = xas->xa_shift;
- unsigned char sibs = xas->xa_sibs;
- xas->xa_index |= ((sibs + 1UL) << shift) - 1;
- if (xas_is_node(xas) && xas->xa_node->shift == xas->xa_shift)
- xas->xa_offset |= sibs;
- xas->xa_shift = 0;
- xas->xa_sibs = 0;
- for (;;) {
- xas_create(xas, true);
- if (xas_error(xas))
- goto restore;
- if (xas->xa_index <= (index | XA_CHUNK_MASK))
- goto success;
- xas->xa_index -= XA_CHUNK_SIZE;
- for (;;) {
- struct xa_node *node = xas->xa_node;
- if (node->shift >= shift)
- break;
- xas->xa_node = xa_parent_locked(xas->xa, node);
- xas->xa_offset = node->offset - 1;
- if (node->offset != 0)
- break;
- }
- }
- restore:
- xas->xa_shift = shift;
- xas->xa_sibs = sibs;
- xas->xa_index = index;
- return;
- success:
- xas->xa_index = index;
- if (xas->xa_node)
- xas_set_offset(xas);
- }
- EXPORT_SYMBOL_GPL(xas_create_range);
- static void update_node(struct xa_state *xas, struct xa_node *node,
- int count, int values)
- {
- if (!node || (!count && !values))
- return;
- node->count += count;
- node->nr_values += values;
- XA_NODE_BUG_ON(node, node->count > XA_CHUNK_SIZE);
- XA_NODE_BUG_ON(node, node->nr_values > XA_CHUNK_SIZE);
- xas_update(xas, node);
- if (count < 0)
- xas_delete_node(xas);
- }
- /**
- * xas_store() - Store this entry in the XArray.
- * @xas: XArray operation state.
- * @entry: New entry.
- *
- * If @xas is operating on a multi-index entry, the entry returned by this
- * function is essentially meaningless (it may be an internal entry or it
- * may be %NULL, even if there are non-NULL entries at some of the indices
- * covered by the range). This is not a problem for any current users,
- * and can be changed if needed.
- *
- * Return: The old entry at this index.
- */
- void *xas_store(struct xa_state *xas, void *entry)
- {
- struct xa_node *node;
- void __rcu **slot = &xas->xa->xa_head;
- unsigned int offset, max;
- int count = 0;
- int values = 0;
- void *first, *next;
- bool value = xa_is_value(entry);
- if (entry) {
- bool allow_root = !xa_is_node(entry) && !xa_is_zero(entry);
- first = xas_create(xas, allow_root);
- } else {
- first = xas_load(xas);
- }
- if (xas_invalid(xas))
- return first;
- node = xas->xa_node;
- if (node && (xas->xa_shift < node->shift))
- xas->xa_sibs = 0;
- if ((first == entry) && !xas->xa_sibs)
- return first;
- next = first;
- offset = xas->xa_offset;
- max = xas->xa_offset + xas->xa_sibs;
- if (node) {
- slot = &node->slots[offset];
- if (xas->xa_sibs)
- xas_squash_marks(xas);
- }
- if (!entry)
- xas_init_marks(xas);
- for (;;) {
- /*
- * Must clear the marks before setting the entry to NULL,
- * otherwise xas_for_each_marked may find a NULL entry and
- * stop early. rcu_assign_pointer contains a release barrier
- * so the mark clearing will appear to happen before the
- * entry is set to NULL.
- */
- rcu_assign_pointer(*slot, entry);
- if (xa_is_node(next) && (!node || node->shift))
- xas_free_nodes(xas, xa_to_node(next));
- if (!node)
- break;
- count += !next - !entry;
- values += !xa_is_value(first) - !value;
- if (entry) {
- if (offset == max)
- break;
- if (!xa_is_sibling(entry))
- entry = xa_mk_sibling(xas->xa_offset);
- } else {
- if (offset == XA_CHUNK_MASK)
- break;
- }
- next = xa_entry_locked(xas->xa, node, ++offset);
- if (!xa_is_sibling(next)) {
- if (!entry && (offset > max))
- break;
- first = next;
- }
- slot++;
- }
- update_node(xas, node, count, values);
- return first;
- }
- EXPORT_SYMBOL_GPL(xas_store);
- /**
- * xas_get_mark() - Returns the state of this mark.
- * @xas: XArray operation state.
- * @mark: Mark number.
- *
- * Return: true if the mark is set, false if the mark is clear or @xas
- * is in an error state.
- */
- bool xas_get_mark(const struct xa_state *xas, xa_mark_t mark)
- {
- if (xas_invalid(xas))
- return false;
- if (!xas->xa_node)
- return xa_marked(xas->xa, mark);
- return node_get_mark(xas->xa_node, xas->xa_offset, mark);
- }
- EXPORT_SYMBOL_GPL(xas_get_mark);
- /**
- * xas_set_mark() - Sets the mark on this entry and its parents.
- * @xas: XArray operation state.
- * @mark: Mark number.
- *
- * Sets the specified mark on this entry, and walks up the tree setting it
- * on all the ancestor entries. Does nothing if @xas has not been walked to
- * an entry, or is in an error state.
- */
- void xas_set_mark(const struct xa_state *xas, xa_mark_t mark)
- {
- struct xa_node *node = xas->xa_node;
- unsigned int offset = xas->xa_offset;
- if (xas_invalid(xas))
- return;
- while (node) {
- if (node_set_mark(node, offset, mark))
- return;
- offset = node->offset;
- node = xa_parent_locked(xas->xa, node);
- }
- if (!xa_marked(xas->xa, mark))
- xa_mark_set(xas->xa, mark);
- }
- EXPORT_SYMBOL_GPL(xas_set_mark);
- /**
- * xas_clear_mark() - Clears the mark on this entry and its parents.
- * @xas: XArray operation state.
- * @mark: Mark number.
- *
- * Clears the specified mark on this entry, and walks back to the head
- * attempting to clear it on all the ancestor entries. Does nothing if
- * @xas has not been walked to an entry, or is in an error state.
- */
- void xas_clear_mark(const struct xa_state *xas, xa_mark_t mark)
- {
- struct xa_node *node = xas->xa_node;
- unsigned int offset = xas->xa_offset;
- if (xas_invalid(xas))
- return;
- while (node) {
- if (!node_clear_mark(node, offset, mark))
- return;
- if (node_any_mark(node, mark))
- return;
- offset = node->offset;
- node = xa_parent_locked(xas->xa, node);
- }
- if (xa_marked(xas->xa, mark))
- xa_mark_clear(xas->xa, mark);
- }
- EXPORT_SYMBOL_GPL(xas_clear_mark);
- /**
- * xas_init_marks() - Initialise all marks for the entry
- * @xas: Array operations state.
- *
- * Initialise all marks for the entry specified by @xas. If we're tracking
- * free entries with a mark, we need to set it on all entries. All other
- * marks are cleared.
- *
- * This implementation is not as efficient as it could be; we may walk
- * up the tree multiple times.
- */
- void xas_init_marks(const struct xa_state *xas)
- {
- xa_mark_t mark = 0;
- for (;;) {
- if (xa_track_free(xas->xa) && mark == XA_FREE_MARK)
- xas_set_mark(xas, mark);
- else
- xas_clear_mark(xas, mark);
- if (mark == XA_MARK_MAX)
- break;
- mark_inc(mark);
- }
- }
- EXPORT_SYMBOL_GPL(xas_init_marks);
- #ifdef CONFIG_XARRAY_MULTI
- static unsigned int node_get_marks(struct xa_node *node, unsigned int offset)
- {
- unsigned int marks = 0;
- xa_mark_t mark = XA_MARK_0;
- for (;;) {
- if (node_get_mark(node, offset, mark))
- marks |= 1 << (__force unsigned int)mark;
- if (mark == XA_MARK_MAX)
- break;
- mark_inc(mark);
- }
- return marks;
- }
- static void node_set_marks(struct xa_node *node, unsigned int offset,
- struct xa_node *child, unsigned int marks)
- {
- xa_mark_t mark = XA_MARK_0;
- for (;;) {
- if (marks & (1 << (__force unsigned int)mark)) {
- node_set_mark(node, offset, mark);
- if (child)
- node_mark_all(child, mark);
- }
- if (mark == XA_MARK_MAX)
- break;
- mark_inc(mark);
- }
- }
- /**
- * xas_split_alloc() - Allocate memory for splitting an entry.
- * @xas: XArray operation state.
- * @entry: New entry which will be stored in the array.
- * @order: New entry order.
- * @gfp: Memory allocation flags.
- *
- * This function should be called before calling xas_split().
- * If necessary, it will allocate new nodes (and fill them with @entry)
- * to prepare for the upcoming split of an entry of @order size into
- * entries of the order stored in the @xas.
- *
- * Context: May sleep if @gfp flags permit.
- */
- void xas_split_alloc(struct xa_state *xas, void *entry, unsigned int order,
- gfp_t gfp)
- {
- unsigned int sibs = (1 << (order % XA_CHUNK_SHIFT)) - 1;
- unsigned int mask = xas->xa_sibs;
- /* XXX: no support for splitting really large entries yet */
- if (WARN_ON(xas->xa_shift + 2 * XA_CHUNK_SHIFT < order))
- goto nomem;
- if (xas->xa_shift + XA_CHUNK_SHIFT > order)
- return;
- do {
- unsigned int i;
- void *sibling = NULL;
- struct xa_node *node;
- node = kmem_cache_alloc(radix_tree_node_cachep, gfp);
- if (!node)
- goto nomem;
- node->array = xas->xa;
- for (i = 0; i < XA_CHUNK_SIZE; i++) {
- if ((i & mask) == 0) {
- RCU_INIT_POINTER(node->slots[i], entry);
- sibling = xa_mk_sibling(i);
- } else {
- RCU_INIT_POINTER(node->slots[i], sibling);
- }
- }
- RCU_INIT_POINTER(node->parent, xas->xa_alloc);
- xas->xa_alloc = node;
- } while (sibs-- > 0);
- return;
- nomem:
- xas_destroy(xas);
- xas_set_err(xas, -ENOMEM);
- }
- EXPORT_SYMBOL_GPL(xas_split_alloc);
- /**
- * xas_split() - Split a multi-index entry into smaller entries.
- * @xas: XArray operation state.
- * @entry: New entry to store in the array.
- * @order: New entry order.
- *
- * The value in the entry is copied to all the replacement entries.
- *
- * Context: Any context. The caller should hold the xa_lock.
- */
- void xas_split(struct xa_state *xas, void *entry, unsigned int order)
- {
- unsigned int sibs = (1 << (order % XA_CHUNK_SHIFT)) - 1;
- unsigned int offset, marks;
- struct xa_node *node;
- void *curr = xas_load(xas);
- int values = 0;
- node = xas->xa_node;
- if (xas_top(node))
- return;
- marks = node_get_marks(node, xas->xa_offset);
- offset = xas->xa_offset + sibs;
- do {
- if (xas->xa_shift < node->shift) {
- struct xa_node *child = xas->xa_alloc;
- xas->xa_alloc = rcu_dereference_raw(child->parent);
- child->shift = node->shift - XA_CHUNK_SHIFT;
- child->offset = offset;
- child->count = XA_CHUNK_SIZE;
- child->nr_values = xa_is_value(entry) ?
- XA_CHUNK_SIZE : 0;
- RCU_INIT_POINTER(child->parent, node);
- node_set_marks(node, offset, child, marks);
- rcu_assign_pointer(node->slots[offset],
- xa_mk_node(child));
- if (xa_is_value(curr))
- values--;
- xas_update(xas, child);
- } else {
- unsigned int canon = offset - xas->xa_sibs;
- node_set_marks(node, canon, NULL, marks);
- rcu_assign_pointer(node->slots[canon], entry);
- while (offset > canon)
- rcu_assign_pointer(node->slots[offset--],
- xa_mk_sibling(canon));
- values += (xa_is_value(entry) - xa_is_value(curr)) *
- (xas->xa_sibs + 1);
- }
- } while (offset-- > xas->xa_offset);
- node->nr_values += values;
- xas_update(xas, node);
- }
- EXPORT_SYMBOL_GPL(xas_split);
- #endif
- /**
- * xas_pause() - Pause a walk to drop a lock.
- * @xas: XArray operation state.
- *
- * Some users need to pause a walk and drop the lock they're holding in
- * order to yield to a higher priority thread or carry out an operation
- * on an entry. Those users should call this function before they drop
- * the lock. It resets the @xas to be suitable for the next iteration
- * of the loop after the user has reacquired the lock. If most entries
- * found during a walk require you to call xas_pause(), the xa_for_each()
- * iterator may be more appropriate.
- *
- * Note that xas_pause() only works for forward iteration. If a user needs
- * to pause a reverse iteration, we will need a xas_pause_rev().
- */
- void xas_pause(struct xa_state *xas)
- {
- struct xa_node *node = xas->xa_node;
- if (xas_invalid(xas))
- return;
- xas->xa_node = XAS_RESTART;
- if (node) {
- unsigned long offset = xas->xa_offset;
- while (++offset < XA_CHUNK_SIZE) {
- if (!xa_is_sibling(xa_entry(xas->xa, node, offset)))
- break;
- }
- xas->xa_index += (offset - xas->xa_offset) << node->shift;
- if (xas->xa_index == 0)
- xas->xa_node = XAS_BOUNDS;
- } else {
- xas->xa_index++;
- }
- }
- EXPORT_SYMBOL_GPL(xas_pause);
- /*
- * __xas_prev() - Find the previous entry in the XArray.
- * @xas: XArray operation state.
- *
- * Helper function for xas_prev() which handles all the complex cases
- * out of line.
- */
- void *__xas_prev(struct xa_state *xas)
- {
- void *entry;
- if (!xas_frozen(xas->xa_node))
- xas->xa_index--;
- if (!xas->xa_node)
- return set_bounds(xas);
- if (xas_not_node(xas->xa_node))
- return xas_load(xas);
- if (xas->xa_offset != get_offset(xas->xa_index, xas->xa_node))
- xas->xa_offset--;
- while (xas->xa_offset == 255) {
- xas->xa_offset = xas->xa_node->offset - 1;
- xas->xa_node = xa_parent(xas->xa, xas->xa_node);
- if (!xas->xa_node)
- return set_bounds(xas);
- }
- for (;;) {
- entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset);
- if (!xa_is_node(entry))
- return entry;
- xas->xa_node = xa_to_node(entry);
- xas_set_offset(xas);
- }
- }
- EXPORT_SYMBOL_GPL(__xas_prev);
- /*
- * __xas_next() - Find the next entry in the XArray.
- * @xas: XArray operation state.
- *
- * Helper function for xas_next() which handles all the complex cases
- * out of line.
- */
- void *__xas_next(struct xa_state *xas)
- {
- void *entry;
- if (!xas_frozen(xas->xa_node))
- xas->xa_index++;
- if (!xas->xa_node)
- return set_bounds(xas);
- if (xas_not_node(xas->xa_node))
- return xas_load(xas);
- if (xas->xa_offset != get_offset(xas->xa_index, xas->xa_node))
- xas->xa_offset++;
- while (xas->xa_offset == XA_CHUNK_SIZE) {
- xas->xa_offset = xas->xa_node->offset + 1;
- xas->xa_node = xa_parent(xas->xa, xas->xa_node);
- if (!xas->xa_node)
- return set_bounds(xas);
- }
- for (;;) {
- entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset);
- if (!xa_is_node(entry))
- return entry;
- xas->xa_node = xa_to_node(entry);
- xas_set_offset(xas);
- }
- }
- EXPORT_SYMBOL_GPL(__xas_next);
- /**
- * xas_find() - Find the next present entry in the XArray.
- * @xas: XArray operation state.
- * @max: Highest index to return.
- *
- * If the @xas has not yet been walked to an entry, return the entry
- * which has an index >= xas.xa_index. If it has been walked, the entry
- * currently being pointed at has been processed, and so we move to the
- * next entry.
- *
- * If no entry is found and the array is smaller than @max, the iterator
- * is set to the smallest index not yet in the array. This allows @xas
- * to be immediately passed to xas_store().
- *
- * Return: The entry, if found, otherwise %NULL.
- */
- void *xas_find(struct xa_state *xas, unsigned long max)
- {
- void *entry;
- if (xas_error(xas) || xas->xa_node == XAS_BOUNDS)
- return NULL;
- if (xas->xa_index > max)
- return set_bounds(xas);
- if (!xas->xa_node) {
- xas->xa_index = 1;
- return set_bounds(xas);
- } else if (xas->xa_node == XAS_RESTART) {
- entry = xas_load(xas);
- if (entry || xas_not_node(xas->xa_node))
- return entry;
- } else if (!xas->xa_node->shift &&
- xas->xa_offset != (xas->xa_index & XA_CHUNK_MASK)) {
- xas->xa_offset = ((xas->xa_index - 1) & XA_CHUNK_MASK) + 1;
- }
- xas_advance(xas);
- while (xas->xa_node && (xas->xa_index <= max)) {
- if (unlikely(xas->xa_offset == XA_CHUNK_SIZE)) {
- xas->xa_offset = xas->xa_node->offset + 1;
- xas->xa_node = xa_parent(xas->xa, xas->xa_node);
- continue;
- }
- entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset);
- if (xa_is_node(entry)) {
- xas->xa_node = xa_to_node(entry);
- xas->xa_offset = 0;
- continue;
- }
- if (entry && !xa_is_sibling(entry))
- return entry;
- xas_advance(xas);
- }
- if (!xas->xa_node)
- xas->xa_node = XAS_BOUNDS;
- return NULL;
- }
- EXPORT_SYMBOL_GPL(xas_find);
- /**
- * xas_find_marked() - Find the next marked entry in the XArray.
- * @xas: XArray operation state.
- * @max: Highest index to return.
- * @mark: Mark number to search for.
- *
- * If the @xas has not yet been walked to an entry, return the marked entry
- * which has an index >= xas.xa_index. If it has been walked, the entry
- * currently being pointed at has been processed, and so we return the
- * first marked entry with an index > xas.xa_index.
- *
- * If no marked entry is found and the array is smaller than @max, @xas is
- * set to the bounds state and xas->xa_index is set to the smallest index
- * not yet in the array. This allows @xas to be immediately passed to
- * xas_store().
- *
- * If no entry is found before @max is reached, @xas is set to the restart
- * state.
- *
- * Return: The entry, if found, otherwise %NULL.
- */
- void *xas_find_marked(struct xa_state *xas, unsigned long max, xa_mark_t mark)
- {
- bool advance = true;
- unsigned int offset;
- void *entry;
- if (xas_error(xas))
- return NULL;
- if (xas->xa_index > max)
- goto max;
- if (!xas->xa_node) {
- xas->xa_index = 1;
- goto out;
- } else if (xas_top(xas->xa_node)) {
- advance = false;
- entry = xa_head(xas->xa);
- xas->xa_node = NULL;
- if (xas->xa_index > max_index(entry))
- goto out;
- if (!xa_is_node(entry)) {
- if (xa_marked(xas->xa, mark))
- return entry;
- xas->xa_index = 1;
- goto out;
- }
- xas->xa_node = xa_to_node(entry);
- xas->xa_offset = xas->xa_index >> xas->xa_node->shift;
- }
- while (xas->xa_index <= max) {
- if (unlikely(xas->xa_offset == XA_CHUNK_SIZE)) {
- xas->xa_offset = xas->xa_node->offset + 1;
- xas->xa_node = xa_parent(xas->xa, xas->xa_node);
- if (!xas->xa_node)
- break;
- advance = false;
- continue;
- }
- if (!advance) {
- entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset);
- if (xa_is_sibling(entry)) {
- xas->xa_offset = xa_to_sibling(entry);
- xas_move_index(xas, xas->xa_offset);
- }
- }
- offset = xas_find_chunk(xas, advance, mark);
- if (offset > xas->xa_offset) {
- advance = false;
- xas_move_index(xas, offset);
- /* Mind the wrap */
- if ((xas->xa_index - 1) >= max)
- goto max;
- xas->xa_offset = offset;
- if (offset == XA_CHUNK_SIZE)
- continue;
- }
- entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset);
- if (!entry && !(xa_track_free(xas->xa) && mark == XA_FREE_MARK))
- continue;
- if (!xa_is_node(entry))
- return entry;
- xas->xa_node = xa_to_node(entry);
- xas_set_offset(xas);
- }
- out:
- if (xas->xa_index > max)
- goto max;
- return set_bounds(xas);
- max:
- xas->xa_node = XAS_RESTART;
- return NULL;
- }
- EXPORT_SYMBOL_GPL(xas_find_marked);
- /**
- * xas_find_conflict() - Find the next present entry in a range.
- * @xas: XArray operation state.
- *
- * The @xas describes both a range and a position within that range.
- *
- * Context: Any context. Expects xa_lock to be held.
- * Return: The next entry in the range covered by @xas or %NULL.
- */
- void *xas_find_conflict(struct xa_state *xas)
- {
- void *curr;
- if (xas_error(xas))
- return NULL;
- if (!xas->xa_node)
- return NULL;
- if (xas_top(xas->xa_node)) {
- curr = xas_start(xas);
- if (!curr)
- return NULL;
- while (xa_is_node(curr)) {
- struct xa_node *node = xa_to_node(curr);
- curr = xas_descend(xas, node);
- }
- if (curr)
- return curr;
- }
- if (xas->xa_node->shift > xas->xa_shift)
- return NULL;
- for (;;) {
- if (xas->xa_node->shift == xas->xa_shift) {
- if ((xas->xa_offset & xas->xa_sibs) == xas->xa_sibs)
- break;
- } else if (xas->xa_offset == XA_CHUNK_MASK) {
- xas->xa_offset = xas->xa_node->offset;
- xas->xa_node = xa_parent_locked(xas->xa, xas->xa_node);
- if (!xas->xa_node)
- break;
- continue;
- }
- curr = xa_entry_locked(xas->xa, xas->xa_node, ++xas->xa_offset);
- if (xa_is_sibling(curr))
- continue;
- while (xa_is_node(curr)) {
- xas->xa_node = xa_to_node(curr);
- xas->xa_offset = 0;
- curr = xa_entry_locked(xas->xa, xas->xa_node, 0);
- }
- if (curr)
- return curr;
- }
- xas->xa_offset -= xas->xa_sibs;
- return NULL;
- }
- EXPORT_SYMBOL_GPL(xas_find_conflict);
- /**
- * xa_load() - Load an entry from an XArray.
- * @xa: XArray.
- * @index: index into array.
- *
- * Context: Any context. Takes and releases the RCU lock.
- * Return: The entry at @index in @xa.
- */
- void *xa_load(struct xarray *xa, unsigned long index)
- {
- XA_STATE(xas, xa, index);
- void *entry;
- rcu_read_lock();
- do {
- entry = xas_load(&xas);
- if (xa_is_zero(entry))
- entry = NULL;
- } while (xas_retry(&xas, entry));
- rcu_read_unlock();
- return entry;
- }
- EXPORT_SYMBOL(xa_load);
- static void *xas_result(struct xa_state *xas, void *curr)
- {
- if (xa_is_zero(curr))
- return NULL;
- if (xas_error(xas))
- curr = xas->xa_node;
- return curr;
- }
- /**
- * __xa_erase() - Erase this entry from the XArray while locked.
- * @xa: XArray.
- * @index: Index into array.
- *
- * After this function returns, loading from @index will return %NULL.
- * If the index is part of a multi-index entry, all indices will be erased
- * and none of the entries will be part of a multi-index entry.
- *
- * Context: Any context. Expects xa_lock to be held on entry.
- * Return: The entry which used to be at this index.
- */
- void *__xa_erase(struct xarray *xa, unsigned long index)
- {
- XA_STATE(xas, xa, index);
- return xas_result(&xas, xas_store(&xas, NULL));
- }
- EXPORT_SYMBOL(__xa_erase);
- /**
- * xa_erase() - Erase this entry from the XArray.
- * @xa: XArray.
- * @index: Index of entry.
- *
- * After this function returns, loading from @index will return %NULL.
- * If the index is part of a multi-index entry, all indices will be erased
- * and none of the entries will be part of a multi-index entry.
- *
- * Context: Any context. Takes and releases the xa_lock.
- * Return: The entry which used to be at this index.
- */
- void *xa_erase(struct xarray *xa, unsigned long index)
- {
- void *entry;
- xa_lock(xa);
- entry = __xa_erase(xa, index);
- xa_unlock(xa);
- return entry;
- }
- EXPORT_SYMBOL(xa_erase);
- /**
- * __xa_store() - Store this entry in the XArray.
- * @xa: XArray.
- * @index: Index into array.
- * @entry: New entry.
- * @gfp: Memory allocation flags.
- *
- * You must already be holding the xa_lock when calling this function.
- * It will drop the lock if needed to allocate memory, and then reacquire
- * it afterwards.
- *
- * Context: Any context. Expects xa_lock to be held on entry. May
- * release and reacquire xa_lock if @gfp flags permit.
- * Return: The old entry at this index or xa_err() if an error happened.
- */
- void *__xa_store(struct xarray *xa, unsigned long index, void *entry, gfp_t gfp)
- {
- XA_STATE(xas, xa, index);
- void *curr;
- if (WARN_ON_ONCE(xa_is_advanced(entry)))
- return XA_ERROR(-EINVAL);
- if (xa_track_free(xa) && !entry)
- entry = XA_ZERO_ENTRY;
- do {
- curr = xas_store(&xas, entry);
- if (xa_track_free(xa))
- xas_clear_mark(&xas, XA_FREE_MARK);
- } while (__xas_nomem(&xas, gfp));
- return xas_result(&xas, curr);
- }
- EXPORT_SYMBOL(__xa_store);
- /**
- * xa_store() - Store this entry in the XArray.
- * @xa: XArray.
- * @index: Index into array.
- * @entry: New entry.
- * @gfp: Memory allocation flags.
- *
- * After this function returns, loads from this index will return @entry.
- * Storing into an existing multi-index entry updates the entry of every index.
- * The marks associated with @index are unaffected unless @entry is %NULL.
- *
- * Context: Any context. Takes and releases the xa_lock.
- * May sleep if the @gfp flags permit.
- * Return: The old entry at this index on success, xa_err(-EINVAL) if @entry
- * cannot be stored in an XArray, or xa_err(-ENOMEM) if memory allocation
- * failed.
- */
- void *xa_store(struct xarray *xa, unsigned long index, void *entry, gfp_t gfp)
- {
- void *curr;
- xa_lock(xa);
- curr = __xa_store(xa, index, entry, gfp);
- xa_unlock(xa);
- return curr;
- }
- EXPORT_SYMBOL(xa_store);
- /**
- * __xa_cmpxchg() - Store this entry in the XArray.
- * @xa: XArray.
- * @index: Index into array.
- * @old: Old value to test against.
- * @entry: New entry.
- * @gfp: Memory allocation flags.
- *
- * You must already be holding the xa_lock when calling this function.
- * It will drop the lock if needed to allocate memory, and then reacquire
- * it afterwards.
- *
- * Context: Any context. Expects xa_lock to be held on entry. May
- * release and reacquire xa_lock if @gfp flags permit.
- * Return: The old entry at this index or xa_err() if an error happened.
- */
- void *__xa_cmpxchg(struct xarray *xa, unsigned long index,
- void *old, void *entry, gfp_t gfp)
- {
- XA_STATE(xas, xa, index);
- void *curr;
- if (WARN_ON_ONCE(xa_is_advanced(entry)))
- return XA_ERROR(-EINVAL);
- do {
- curr = xas_load(&xas);
- if (curr == old) {
- xas_store(&xas, entry);
- if (xa_track_free(xa) && entry && !curr)
- xas_clear_mark(&xas, XA_FREE_MARK);
- }
- } while (__xas_nomem(&xas, gfp));
- return xas_result(&xas, curr);
- }
- EXPORT_SYMBOL(__xa_cmpxchg);
- /**
- * __xa_insert() - Store this entry in the XArray if no entry is present.
- * @xa: XArray.
- * @index: Index into array.
- * @entry: New entry.
- * @gfp: Memory allocation flags.
- *
- * Inserting a NULL entry will store a reserved entry (like xa_reserve())
- * if no entry is present. Inserting will fail if a reserved entry is
- * present, even though loading from this index will return NULL.
- *
- * Context: Any context. Expects xa_lock to be held on entry. May
- * release and reacquire xa_lock if @gfp flags permit.
- * Return: 0 if the store succeeded. -EBUSY if another entry was present.
- * -ENOMEM if memory could not be allocated.
- */
- int __xa_insert(struct xarray *xa, unsigned long index, void *entry, gfp_t gfp)
- {
- XA_STATE(xas, xa, index);
- void *curr;
- if (WARN_ON_ONCE(xa_is_advanced(entry)))
- return -EINVAL;
- if (!entry)
- entry = XA_ZERO_ENTRY;
- do {
- curr = xas_load(&xas);
- if (!curr) {
- xas_store(&xas, entry);
- if (xa_track_free(xa))
- xas_clear_mark(&xas, XA_FREE_MARK);
- } else {
- xas_set_err(&xas, -EBUSY);
- }
- } while (__xas_nomem(&xas, gfp));
- return xas_error(&xas);
- }
- EXPORT_SYMBOL(__xa_insert);
- #ifdef CONFIG_XARRAY_MULTI
- static void xas_set_range(struct xa_state *xas, unsigned long first,
- unsigned long last)
- {
- unsigned int shift = 0;
- unsigned long sibs = last - first;
- unsigned int offset = XA_CHUNK_MASK;
- xas_set(xas, first);
- while ((first & XA_CHUNK_MASK) == 0) {
- if (sibs < XA_CHUNK_MASK)
- break;
- if ((sibs == XA_CHUNK_MASK) && (offset < XA_CHUNK_MASK))
- break;
- shift += XA_CHUNK_SHIFT;
- if (offset == XA_CHUNK_MASK)
- offset = sibs & XA_CHUNK_MASK;
- sibs >>= XA_CHUNK_SHIFT;
- first >>= XA_CHUNK_SHIFT;
- }
- offset = first & XA_CHUNK_MASK;
- if (offset + sibs > XA_CHUNK_MASK)
- sibs = XA_CHUNK_MASK - offset;
- if ((((first + sibs + 1) << shift) - 1) > last)
- sibs -= 1;
- xas->xa_shift = shift;
- xas->xa_sibs = sibs;
- }
- /**
- * xa_store_range() - Store this entry at a range of indices in the XArray.
- * @xa: XArray.
- * @first: First index to affect.
- * @last: Last index to affect.
- * @entry: New entry.
- * @gfp: Memory allocation flags.
- *
- * After this function returns, loads from any index between @first and @last,
- * inclusive will return @entry.
- * Storing into an existing multi-index entry updates the entry of every index.
- * The marks associated with @index are unaffected unless @entry is %NULL.
- *
- * Context: Process context. Takes and releases the xa_lock. May sleep
- * if the @gfp flags permit.
- * Return: %NULL on success, xa_err(-EINVAL) if @entry cannot be stored in
- * an XArray, or xa_err(-ENOMEM) if memory allocation failed.
- */
- void *xa_store_range(struct xarray *xa, unsigned long first,
- unsigned long last, void *entry, gfp_t gfp)
- {
- XA_STATE(xas, xa, 0);
- if (WARN_ON_ONCE(xa_is_internal(entry)))
- return XA_ERROR(-EINVAL);
- if (last < first)
- return XA_ERROR(-EINVAL);
- do {
- xas_lock(&xas);
- if (entry) {
- unsigned int order = BITS_PER_LONG;
- if (last + 1)
- order = __ffs(last + 1);
- xas_set_order(&xas, last, order);
- xas_create(&xas, true);
- if (xas_error(&xas))
- goto unlock;
- }
- do {
- xas_set_range(&xas, first, last);
- xas_store(&xas, entry);
- if (xas_error(&xas))
- goto unlock;
- first += xas_size(&xas);
- } while (first <= last);
- unlock:
- xas_unlock(&xas);
- } while (xas_nomem(&xas, gfp));
- return xas_result(&xas, NULL);
- }
- EXPORT_SYMBOL(xa_store_range);
- /**
- * xa_get_order() - Get the order of an entry.
- * @xa: XArray.
- * @index: Index of the entry.
- *
- * Return: A number between 0 and 63 indicating the order of the entry.
- */
- int xa_get_order(struct xarray *xa, unsigned long index)
- {
- XA_STATE(xas, xa, index);
- void *entry;
- int order = 0;
- rcu_read_lock();
- entry = xas_load(&xas);
- if (!entry)
- goto unlock;
- if (!xas.xa_node)
- goto unlock;
- for (;;) {
- unsigned int slot = xas.xa_offset + (1 << order);
- if (slot >= XA_CHUNK_SIZE)
- break;
- if (!xa_is_sibling(xas.xa_node->slots[slot]))
- break;
- order++;
- }
- order += xas.xa_node->shift;
- unlock:
- rcu_read_unlock();
- return order;
- }
- EXPORT_SYMBOL(xa_get_order);
- #endif /* CONFIG_XARRAY_MULTI */
- /**
- * __xa_alloc() - Find somewhere to store this entry in the XArray.
- * @xa: XArray.
- * @id: Pointer to ID.
- * @limit: Range for allocated ID.
- * @entry: New entry.
- * @gfp: Memory allocation flags.
- *
- * Finds an empty entry in @xa between @limit.min and @limit.max,
- * stores the index into the @id pointer, then stores the entry at
- * that index. A concurrent lookup will not see an uninitialised @id.
- *
- * Context: Any context. Expects xa_lock to be held on entry. May
- * release and reacquire xa_lock if @gfp flags permit.
- * Return: 0 on success, -ENOMEM if memory could not be allocated or
- * -EBUSY if there are no free entries in @limit.
- */
- int __xa_alloc(struct xarray *xa, u32 *id, void *entry,
- struct xa_limit limit, gfp_t gfp)
- {
- XA_STATE(xas, xa, 0);
- if (WARN_ON_ONCE(xa_is_advanced(entry)))
- return -EINVAL;
- if (WARN_ON_ONCE(!xa_track_free(xa)))
- return -EINVAL;
- if (!entry)
- entry = XA_ZERO_ENTRY;
- do {
- xas.xa_index = limit.min;
- xas_find_marked(&xas, limit.max, XA_FREE_MARK);
- if (xas.xa_node == XAS_RESTART)
- xas_set_err(&xas, -EBUSY);
- else
- *id = xas.xa_index;
- xas_store(&xas, entry);
- xas_clear_mark(&xas, XA_FREE_MARK);
- } while (__xas_nomem(&xas, gfp));
- return xas_error(&xas);
- }
- EXPORT_SYMBOL(__xa_alloc);
- /**
- * __xa_alloc_cyclic() - Find somewhere to store this entry in the XArray.
- * @xa: XArray.
- * @id: Pointer to ID.
- * @entry: New entry.
- * @limit: Range of allocated ID.
- * @next: Pointer to next ID to allocate.
- * @gfp: Memory allocation flags.
- *
- * Finds an empty entry in @xa between @limit.min and @limit.max,
- * stores the index into the @id pointer, then stores the entry at
- * that index. A concurrent lookup will not see an uninitialised @id.
- * The search for an empty entry will start at @next and will wrap
- * around if necessary.
- *
- * Context: Any context. Expects xa_lock to be held on entry. May
- * release and reacquire xa_lock if @gfp flags permit.
- * Return: 0 if the allocation succeeded without wrapping. 1 if the
- * allocation succeeded after wrapping, -ENOMEM if memory could not be
- * allocated or -EBUSY if there are no free entries in @limit.
- */
- int __xa_alloc_cyclic(struct xarray *xa, u32 *id, void *entry,
- struct xa_limit limit, u32 *next, gfp_t gfp)
- {
- u32 min = limit.min;
- int ret;
- limit.min = max(min, *next);
- ret = __xa_alloc(xa, id, entry, limit, gfp);
- if ((xa->xa_flags & XA_FLAGS_ALLOC_WRAPPED) && ret == 0) {
- xa->xa_flags &= ~XA_FLAGS_ALLOC_WRAPPED;
- ret = 1;
- }
- if (ret < 0 && limit.min > min) {
- limit.min = min;
- ret = __xa_alloc(xa, id, entry, limit, gfp);
- if (ret == 0)
- ret = 1;
- }
- if (ret >= 0) {
- *next = *id + 1;
- if (*next == 0)
- xa->xa_flags |= XA_FLAGS_ALLOC_WRAPPED;
- }
- return ret;
- }
- EXPORT_SYMBOL(__xa_alloc_cyclic);
- /**
- * __xa_set_mark() - Set this mark on this entry while locked.
- * @xa: XArray.
- * @index: Index of entry.
- * @mark: Mark number.
- *
- * Attempting to set a mark on a %NULL entry does not succeed.
- *
- * Context: Any context. Expects xa_lock to be held on entry.
- */
- void __xa_set_mark(struct xarray *xa, unsigned long index, xa_mark_t mark)
- {
- XA_STATE(xas, xa, index);
- void *entry = xas_load(&xas);
- if (entry)
- xas_set_mark(&xas, mark);
- }
- EXPORT_SYMBOL(__xa_set_mark);
- /**
- * __xa_clear_mark() - Clear this mark on this entry while locked.
- * @xa: XArray.
- * @index: Index of entry.
- * @mark: Mark number.
- *
- * Context: Any context. Expects xa_lock to be held on entry.
- */
- void __xa_clear_mark(struct xarray *xa, unsigned long index, xa_mark_t mark)
- {
- XA_STATE(xas, xa, index);
- void *entry = xas_load(&xas);
- if (entry)
- xas_clear_mark(&xas, mark);
- }
- EXPORT_SYMBOL(__xa_clear_mark);
- /**
- * xa_get_mark() - Inquire whether this mark is set on this entry.
- * @xa: XArray.
- * @index: Index of entry.
- * @mark: Mark number.
- *
- * This function uses the RCU read lock, so the result may be out of date
- * by the time it returns. If you need the result to be stable, use a lock.
- *
- * Context: Any context. Takes and releases the RCU lock.
- * Return: True if the entry at @index has this mark set, false if it doesn't.
- */
- bool xa_get_mark(struct xarray *xa, unsigned long index, xa_mark_t mark)
- {
- XA_STATE(xas, xa, index);
- void *entry;
- rcu_read_lock();
- entry = xas_start(&xas);
- while (xas_get_mark(&xas, mark)) {
- if (!xa_is_node(entry))
- goto found;
- entry = xas_descend(&xas, xa_to_node(entry));
- }
- rcu_read_unlock();
- return false;
- found:
- rcu_read_unlock();
- return true;
- }
- EXPORT_SYMBOL(xa_get_mark);
- /**
- * xa_set_mark() - Set this mark on this entry.
- * @xa: XArray.
- * @index: Index of entry.
- * @mark: Mark number.
- *
- * Attempting to set a mark on a %NULL entry does not succeed.
- *
- * Context: Process context. Takes and releases the xa_lock.
- */
- void xa_set_mark(struct xarray *xa, unsigned long index, xa_mark_t mark)
- {
- xa_lock(xa);
- __xa_set_mark(xa, index, mark);
- xa_unlock(xa);
- }
- EXPORT_SYMBOL(xa_set_mark);
- /**
- * xa_clear_mark() - Clear this mark on this entry.
- * @xa: XArray.
- * @index: Index of entry.
- * @mark: Mark number.
- *
- * Clearing a mark always succeeds.
- *
- * Context: Process context. Takes and releases the xa_lock.
- */
- void xa_clear_mark(struct xarray *xa, unsigned long index, xa_mark_t mark)
- {
- xa_lock(xa);
- __xa_clear_mark(xa, index, mark);
- xa_unlock(xa);
- }
- EXPORT_SYMBOL(xa_clear_mark);
- /**
- * xa_find() - Search the XArray for an entry.
- * @xa: XArray.
- * @indexp: Pointer to an index.
- * @max: Maximum index to search to.
- * @filter: Selection criterion.
- *
- * Finds the entry in @xa which matches the @filter, and has the lowest
- * index that is at least @indexp and no more than @max.
- * If an entry is found, @indexp is updated to be the index of the entry.
- * This function is protected by the RCU read lock, so it may not find
- * entries which are being simultaneously added. It will not return an
- * %XA_RETRY_ENTRY; if you need to see retry entries, use xas_find().
- *
- * Context: Any context. Takes and releases the RCU lock.
- * Return: The entry, if found, otherwise %NULL.
- */
- void *xa_find(struct xarray *xa, unsigned long *indexp,
- unsigned long max, xa_mark_t filter)
- {
- XA_STATE(xas, xa, *indexp);
- void *entry;
- rcu_read_lock();
- do {
- if ((__force unsigned int)filter < XA_MAX_MARKS)
- entry = xas_find_marked(&xas, max, filter);
- else
- entry = xas_find(&xas, max);
- } while (xas_retry(&xas, entry));
- rcu_read_unlock();
- if (entry)
- *indexp = xas.xa_index;
- return entry;
- }
- EXPORT_SYMBOL(xa_find);
- static bool xas_sibling(struct xa_state *xas)
- {
- struct xa_node *node = xas->xa_node;
- unsigned long mask;
- if (!IS_ENABLED(CONFIG_XARRAY_MULTI) || !node)
- return false;
- mask = (XA_CHUNK_SIZE << node->shift) - 1;
- return (xas->xa_index & mask) >
- ((unsigned long)xas->xa_offset << node->shift);
- }
- /**
- * xa_find_after() - Search the XArray for a present entry.
- * @xa: XArray.
- * @indexp: Pointer to an index.
- * @max: Maximum index to search to.
- * @filter: Selection criterion.
- *
- * Finds the entry in @xa which matches the @filter and has the lowest
- * index that is above @indexp and no more than @max.
- * If an entry is found, @indexp is updated to be the index of the entry.
- * This function is protected by the RCU read lock, so it may miss entries
- * which are being simultaneously added. It will not return an
- * %XA_RETRY_ENTRY; if you need to see retry entries, use xas_find().
- *
- * Context: Any context. Takes and releases the RCU lock.
- * Return: The pointer, if found, otherwise %NULL.
- */
- void *xa_find_after(struct xarray *xa, unsigned long *indexp,
- unsigned long max, xa_mark_t filter)
- {
- XA_STATE(xas, xa, *indexp + 1);
- void *entry;
- if (xas.xa_index == 0)
- return NULL;
- rcu_read_lock();
- for (;;) {
- if ((__force unsigned int)filter < XA_MAX_MARKS)
- entry = xas_find_marked(&xas, max, filter);
- else
- entry = xas_find(&xas, max);
- if (xas_invalid(&xas))
- break;
- if (xas_sibling(&xas))
- continue;
- if (!xas_retry(&xas, entry))
- break;
- }
- rcu_read_unlock();
- if (entry)
- *indexp = xas.xa_index;
- return entry;
- }
- EXPORT_SYMBOL(xa_find_after);
- static unsigned int xas_extract_present(struct xa_state *xas, void **dst,
- unsigned long max, unsigned int n)
- {
- void *entry;
- unsigned int i = 0;
- rcu_read_lock();
- xas_for_each(xas, entry, max) {
- if (xas_retry(xas, entry))
- continue;
- dst[i++] = entry;
- if (i == n)
- break;
- }
- rcu_read_unlock();
- return i;
- }
- static unsigned int xas_extract_marked(struct xa_state *xas, void **dst,
- unsigned long max, unsigned int n, xa_mark_t mark)
- {
- void *entry;
- unsigned int i = 0;
- rcu_read_lock();
- xas_for_each_marked(xas, entry, max, mark) {
- if (xas_retry(xas, entry))
- continue;
- dst[i++] = entry;
- if (i == n)
- break;
- }
- rcu_read_unlock();
- return i;
- }
- /**
- * xa_extract() - Copy selected entries from the XArray into a normal array.
- * @xa: The source XArray to copy from.
- * @dst: The buffer to copy entries into.
- * @start: The first index in the XArray eligible to be selected.
- * @max: The last index in the XArray eligible to be selected.
- * @n: The maximum number of entries to copy.
- * @filter: Selection criterion.
- *
- * Copies up to @n entries that match @filter from the XArray. The
- * copied entries will have indices between @start and @max, inclusive.
- *
- * The @filter may be an XArray mark value, in which case entries which are
- * marked with that mark will be copied. It may also be %XA_PRESENT, in
- * which case all entries which are not %NULL will be copied.
- *
- * The entries returned may not represent a snapshot of the XArray at a
- * moment in time. For example, if another thread stores to index 5, then
- * index 10, calling xa_extract() may return the old contents of index 5
- * and the new contents of index 10. Indices not modified while this
- * function is running will not be skipped.
- *
- * If you need stronger guarantees, holding the xa_lock across calls to this
- * function will prevent concurrent modification.
- *
- * Context: Any context. Takes and releases the RCU lock.
- * Return: The number of entries copied.
- */
- unsigned int xa_extract(struct xarray *xa, void **dst, unsigned long start,
- unsigned long max, unsigned int n, xa_mark_t filter)
- {
- XA_STATE(xas, xa, start);
- if (!n)
- return 0;
- if ((__force unsigned int)filter < XA_MAX_MARKS)
- return xas_extract_marked(&xas, dst, max, n, filter);
- return xas_extract_present(&xas, dst, max, n);
- }
- EXPORT_SYMBOL(xa_extract);
- /**
- * xa_delete_node() - Private interface for workingset code.
- * @node: Node to be removed from the tree.
- * @update: Function to call to update ancestor nodes.
- *
- * Context: xa_lock must be held on entry and will not be released.
- */
- void xa_delete_node(struct xa_node *node, xa_update_node_t update)
- {
- struct xa_state xas = {
- .xa = node->array,
- .xa_index = (unsigned long)node->offset <<
- (node->shift + XA_CHUNK_SHIFT),
- .xa_shift = node->shift + XA_CHUNK_SHIFT,
- .xa_offset = node->offset,
- .xa_node = xa_parent_locked(node->array, node),
- .xa_update = update,
- };
- xas_store(&xas, NULL);
- }
- EXPORT_SYMBOL_GPL(xa_delete_node); /* For the benefit of the test suite */
- /**
- * xa_destroy() - Free all internal data structures.
- * @xa: XArray.
- *
- * After calling this function, the XArray is empty and has freed all memory
- * allocated for its internal data structures. You are responsible for
- * freeing the objects referenced by the XArray.
- *
- * Context: Any context. Takes and releases the xa_lock, interrupt-safe.
- */
- void xa_destroy(struct xarray *xa)
- {
- XA_STATE(xas, xa, 0);
- unsigned long flags;
- void *entry;
- xas.xa_node = NULL;
- xas_lock_irqsave(&xas, flags);
- entry = xa_head_locked(xa);
- RCU_INIT_POINTER(xa->xa_head, NULL);
- xas_init_marks(&xas);
- if (xa_zero_busy(xa))
- xa_mark_clear(xa, XA_FREE_MARK);
- /* lockdep checks we're still holding the lock in xas_free_nodes() */
- if (xa_is_node(entry))
- xas_free_nodes(&xas, xa_to_node(entry));
- xas_unlock_irqrestore(&xas, flags);
- }
- EXPORT_SYMBOL(xa_destroy);
- #ifdef XA_DEBUG
- void xa_dump_node(const struct xa_node *node)
- {
- unsigned i, j;
- if (!node)
- return;
- if ((unsigned long)node & 3) {
- pr_cont("node %px\n", node);
- return;
- }
- pr_cont("node %px %s %d parent %px shift %d count %d values %d "
- "array %px list %px %px marks",
- node, node->parent ? "offset" : "max", node->offset,
- node->parent, node->shift, node->count, node->nr_values,
- node->array, node->private_list.prev, node->private_list.next);
- for (i = 0; i < XA_MAX_MARKS; i++)
- for (j = 0; j < XA_MARK_LONGS; j++)
- pr_cont(" %lx", node->marks[i][j]);
- pr_cont("\n");
- }
- void xa_dump_index(unsigned long index, unsigned int shift)
- {
- if (!shift)
- pr_info("%lu: ", index);
- else if (shift >= BITS_PER_LONG)
- pr_info("0-%lu: ", ~0UL);
- else
- pr_info("%lu-%lu: ", index, index | ((1UL << shift) - 1));
- }
- void xa_dump_entry(const void *entry, unsigned long index, unsigned long shift)
- {
- if (!entry)
- return;
- xa_dump_index(index, shift);
- if (xa_is_node(entry)) {
- if (shift == 0) {
- pr_cont("%px\n", entry);
- } else {
- unsigned long i;
- struct xa_node *node = xa_to_node(entry);
- xa_dump_node(node);
- for (i = 0; i < XA_CHUNK_SIZE; i++)
- xa_dump_entry(node->slots[i],
- index + (i << node->shift), node->shift);
- }
- } else if (xa_is_value(entry))
- pr_cont("value %ld (0x%lx) [%px]\n", xa_to_value(entry),
- xa_to_value(entry), entry);
- else if (!xa_is_internal(entry))
- pr_cont("%px\n", entry);
- else if (xa_is_retry(entry))
- pr_cont("retry (%ld)\n", xa_to_internal(entry));
- else if (xa_is_sibling(entry))
- pr_cont("sibling (slot %ld)\n", xa_to_sibling(entry));
- else if (xa_is_zero(entry))
- pr_cont("zero (%ld)\n", xa_to_internal(entry));
- else
- pr_cont("UNKNOWN ENTRY (%px)\n", entry);
- }
- void xa_dump(const struct xarray *xa)
- {
- void *entry = xa->xa_head;
- unsigned int shift = 0;
- pr_info("xarray: %px head %px flags %x marks %d %d %d\n", xa, entry,
- xa->xa_flags, xa_marked(xa, XA_MARK_0),
- xa_marked(xa, XA_MARK_1), xa_marked(xa, XA_MARK_2));
- if (xa_is_node(entry))
- shift = xa_to_node(entry)->shift + XA_CHUNK_SHIFT;
- xa_dump_entry(entry, 0, shift);
- }
- #endif
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