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Diffstat (limited to 'lib/xarray.c')
| -rw-r--r-- | lib/xarray.c | 2301 |
1 files changed, 2301 insertions, 0 deletions
diff --git a/lib/xarray.c b/lib/xarray.c new file mode 100644 index 000000000..75da19a7a --- /dev/null +++ b/lib/xarray.c @@ -0,0 +1,2301 @@ +// 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 |