* Copyright (C) 2001 Momchil Velikov
* Portions Copyright (C) 2001 Christoph Hellwig
* Copyright (C) 2006 Nick Piggin
+ * Copyright (C) 2012 Konstantin Khlebnikov
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
preempt_enable();
}
+/**
+ * struct radix_tree_iter - radix tree iterator state
+ *
+ * @index: index of current slot
+ * @next_index: next-to-last index for this chunk
+ * @tags: bit-mask for tag-iterating
+ *
+ * This radix tree iterator works in terms of "chunks" of slots. A chunk is a
+ * subinterval of slots contained within one radix tree leaf node. It is
+ * described by a pointer to its first slot and a struct radix_tree_iter
+ * which holds the chunk's position in the tree and its size. For tagged
+ * iteration radix_tree_iter also holds the slots' bit-mask for one chosen
+ * radix tree tag.
+ */
+struct radix_tree_iter {
+ unsigned long index;
+ unsigned long next_index;
+ unsigned long tags;
+};
+
+#define RADIX_TREE_ITER_TAG_MASK 0x00FF /* tag index in lower byte */
+#define RADIX_TREE_ITER_TAGGED 0x0100 /* lookup tagged slots */
+#define RADIX_TREE_ITER_CONTIG 0x0200 /* stop at first hole */
+
+/**
+ * radix_tree_iter_init - initialize radix tree iterator
+ *
+ * @iter: pointer to iterator state
+ * @start: iteration starting index
+ * Returns: NULL
+ */
+static __always_inline void **
+radix_tree_iter_init(struct radix_tree_iter *iter, unsigned long start)
+{
+ /*
+ * Leave iter->tags uninitialized. radix_tree_next_chunk() will fill it
+ * in the case of a successful tagged chunk lookup. If the lookup was
+ * unsuccessful or non-tagged then nobody cares about ->tags.
+ *
+ * Set index to zero to bypass next_index overflow protection.
+ * See the comment in radix_tree_next_chunk() for details.
+ */
+ iter->index = 0;
+ iter->next_index = start;
+ return NULL;
+}
+
+/**
+ * radix_tree_next_chunk - find next chunk of slots for iteration
+ *
+ * @root: radix tree root
+ * @iter: iterator state
+ * @flags: RADIX_TREE_ITER_* flags and tag index
+ * Returns: pointer to chunk first slot, or NULL if there no more left
+ *
+ * This function looks up the next chunk in the radix tree starting from
+ * @iter->next_index. It returns a pointer to the chunk's first slot.
+ * Also it fills @iter with data about chunk: position in the tree (index),
+ * its end (next_index), and constructs a bit mask for tagged iterating (tags).
+ */
+void **radix_tree_next_chunk(struct radix_tree_root *root,
+ struct radix_tree_iter *iter, unsigned flags);
+
+/**
+ * radix_tree_chunk_size - get current chunk size
+ *
+ * @iter: pointer to radix tree iterator
+ * Returns: current chunk size
+ */
+static __always_inline unsigned
+radix_tree_chunk_size(struct radix_tree_iter *iter)
+{
+ return iter->next_index - iter->index;
+}
+
+/**
+ * radix_tree_next_slot - find next slot in chunk
+ *
+ * @slot: pointer to current slot
+ * @iter: pointer to interator state
+ * @flags: RADIX_TREE_ITER_*, should be constant
+ * Returns: pointer to next slot, or NULL if there no more left
+ *
+ * This function updates @iter->index in the case of a successful lookup.
+ * For tagged lookup it also eats @iter->tags.
+ */
+static __always_inline void **
+radix_tree_next_slot(void **slot, struct radix_tree_iter *iter, unsigned flags)
+{
+ if (flags & RADIX_TREE_ITER_TAGGED) {
+ iter->tags >>= 1;
+ if (likely(iter->tags & 1ul)) {
+ iter->index++;
+ return slot + 1;
+ }
+ if (!(flags & RADIX_TREE_ITER_CONTIG) && likely(iter->tags)) {
+ unsigned offset = __ffs(iter->tags);
+
+ iter->tags >>= offset;
+ iter->index += offset + 1;
+ return slot + offset + 1;
+ }
+ } else {
+ unsigned size = radix_tree_chunk_size(iter) - 1;
+
+ while (size--) {
+ slot++;
+ iter->index++;
+ if (likely(*slot))
+ return slot;
+ if (flags & RADIX_TREE_ITER_CONTIG)
+ break;
+ }
+ }
+ return NULL;
+}
+
+/**
+ * radix_tree_for_each_chunk - iterate over chunks
+ *
+ * @slot: the void** variable for pointer to chunk first slot
+ * @root: the struct radix_tree_root pointer
+ * @iter: the struct radix_tree_iter pointer
+ * @start: iteration starting index
+ * @flags: RADIX_TREE_ITER_* and tag index
+ *
+ * Locks can be released and reacquired between iterations.
+ */
+#define radix_tree_for_each_chunk(slot, root, iter, start, flags) \
+ for (slot = radix_tree_iter_init(iter, start) ; \
+ (slot = radix_tree_next_chunk(root, iter, flags)) ;)
+
+/**
+ * radix_tree_for_each_chunk_slot - iterate over slots in one chunk
+ *
+ * @slot: the void** variable, at the beginning points to chunk first slot
+ * @iter: the struct radix_tree_iter pointer
+ * @flags: RADIX_TREE_ITER_*, should be constant
+ *
+ * This macro is designed to be nested inside radix_tree_for_each_chunk().
+ * @slot points to the radix tree slot, @iter->index contains its index.
+ */
+#define radix_tree_for_each_chunk_slot(slot, iter, flags) \
+ for (; slot ; slot = radix_tree_next_slot(slot, iter, flags))
+
+/**
+ * radix_tree_for_each_slot - iterate over non-empty slots
+ *
+ * @slot: the void** variable for pointer to slot
+ * @root: the struct radix_tree_root pointer
+ * @iter: the struct radix_tree_iter pointer
+ * @start: iteration starting index
+ *
+ * @slot points to radix tree slot, @iter->index contains its index.
+ */
+#define radix_tree_for_each_slot(slot, root, iter, start) \
+ for (slot = radix_tree_iter_init(iter, start) ; \
+ slot || (slot = radix_tree_next_chunk(root, iter, 0)) ; \
+ slot = radix_tree_next_slot(slot, iter, 0))
+
+/**
+ * radix_tree_for_each_contig - iterate over contiguous slots
+ *
+ * @slot: the void** variable for pointer to slot
+ * @root: the struct radix_tree_root pointer
+ * @iter: the struct radix_tree_iter pointer
+ * @start: iteration starting index
+ *
+ * @slot points to radix tree slot, @iter->index contains its index.
+ */
+#define radix_tree_for_each_contig(slot, root, iter, start) \
+ for (slot = radix_tree_iter_init(iter, start) ; \
+ slot || (slot = radix_tree_next_chunk(root, iter, \
+ RADIX_TREE_ITER_CONTIG)) ; \
+ slot = radix_tree_next_slot(slot, iter, \
+ RADIX_TREE_ITER_CONTIG))
+
+/**
+ * radix_tree_for_each_tagged - iterate over tagged slots
+ *
+ * @slot: the void** variable for pointer to slot
+ * @root: the struct radix_tree_root pointer
+ * @iter: the struct radix_tree_iter pointer
+ * @start: iteration starting index
+ * @tag: tag index
+ *
+ * @slot points to radix tree slot, @iter->index contains its index.
+ */
+#define radix_tree_for_each_tagged(slot, root, iter, start, tag) \
+ for (slot = radix_tree_iter_init(iter, start) ; \
+ slot || (slot = radix_tree_next_chunk(root, iter, \
+ RADIX_TREE_ITER_TAGGED | tag)) ; \
+ slot = radix_tree_next_slot(slot, iter, \
+ RADIX_TREE_ITER_TAGGED))
+
#endif /* _LINUX_RADIX_TREE_H */
* Portions Copyright (C) 2001 Christoph Hellwig
* Copyright (C) 2005 SGI, Christoph Lameter
* Copyright (C) 2006 Nick Piggin
+ * Copyright (C) 2012 Konstantin Khlebnikov
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
}
return 0;
}
+
+/**
+ * radix_tree_find_next_bit - find the next set bit in a memory region
+ *
+ * @addr: The address to base the search on
+ * @size: The bitmap size in bits
+ * @offset: The bitnumber to start searching at
+ *
+ * Unrollable variant of find_next_bit() for constant size arrays.
+ * Tail bits starting from size to roundup(size, BITS_PER_LONG) must be zero.
+ * Returns next bit offset, or size if nothing found.
+ */
+static __always_inline unsigned long
+radix_tree_find_next_bit(const unsigned long *addr,
+ unsigned long size, unsigned long offset)
+{
+ if (!__builtin_constant_p(size))
+ return find_next_bit(addr, size, offset);
+
+ if (offset < size) {
+ unsigned long tmp;
+
+ addr += offset / BITS_PER_LONG;
+ tmp = *addr >> (offset % BITS_PER_LONG);
+ if (tmp)
+ return __ffs(tmp) + offset;
+ offset = (offset + BITS_PER_LONG) & ~(BITS_PER_LONG - 1);
+ while (offset < size) {
+ tmp = *++addr;
+ if (tmp)
+ return __ffs(tmp) + offset;
+ offset += BITS_PER_LONG;
+ }
+ }
+ return size;
+}
+
/*
* This assumes that the caller has performed appropriate preallocation, and
* that the caller has pinned this thread of control to the current CPU.
}
EXPORT_SYMBOL(radix_tree_tag_get);
+/**
+ * radix_tree_next_chunk - find next chunk of slots for iteration
+ *
+ * @root: radix tree root
+ * @iter: iterator state
+ * @flags: RADIX_TREE_ITER_* flags and tag index
+ * Returns: pointer to chunk first slot, or NULL if iteration is over
+ */
+void **radix_tree_next_chunk(struct radix_tree_root *root,
+ struct radix_tree_iter *iter, unsigned flags)
+{
+ unsigned shift, tag = flags & RADIX_TREE_ITER_TAG_MASK;
+ struct radix_tree_node *rnode, *node;
+ unsigned long index, offset;
+
+ if ((flags & RADIX_TREE_ITER_TAGGED) && !root_tag_get(root, tag))
+ return NULL;
+
+ /*
+ * Catch next_index overflow after ~0UL. iter->index never overflows
+ * during iterating; it can be zero only at the beginning.
+ * And we cannot overflow iter->next_index in a single step,
+ * because RADIX_TREE_MAP_SHIFT < BITS_PER_LONG.
+ */
+ index = iter->next_index;
+ if (!index && iter->index)
+ return NULL;
+
+ rnode = rcu_dereference_raw(root->rnode);
+ if (radix_tree_is_indirect_ptr(rnode)) {
+ rnode = indirect_to_ptr(rnode);
+ } else if (rnode && !index) {
+ /* Single-slot tree */
+ iter->index = 0;
+ iter->next_index = 1;
+ iter->tags = 1;
+ return (void **)&root->rnode;
+ } else
+ return NULL;
+
+restart:
+ shift = (rnode->height - 1) * RADIX_TREE_MAP_SHIFT;
+ offset = index >> shift;
+
+ /* Index outside of the tree */
+ if (offset >= RADIX_TREE_MAP_SIZE)
+ return NULL;
+
+ node = rnode;
+ while (1) {
+ if ((flags & RADIX_TREE_ITER_TAGGED) ?
+ !test_bit(offset, node->tags[tag]) :
+ !node->slots[offset]) {
+ /* Hole detected */
+ if (flags & RADIX_TREE_ITER_CONTIG)
+ return NULL;
+
+ if (flags & RADIX_TREE_ITER_TAGGED)
+ offset = radix_tree_find_next_bit(
+ node->tags[tag],
+ RADIX_TREE_MAP_SIZE,
+ offset + 1);
+ else
+ while (++offset < RADIX_TREE_MAP_SIZE) {
+ if (node->slots[offset])
+ break;
+ }
+ index &= ~((RADIX_TREE_MAP_SIZE << shift) - 1);
+ index += offset << shift;
+ /* Overflow after ~0UL */
+ if (!index)
+ return NULL;
+ if (offset == RADIX_TREE_MAP_SIZE)
+ goto restart;
+ }
+
+ /* This is leaf-node */
+ if (!shift)
+ break;
+
+ node = rcu_dereference_raw(node->slots[offset]);
+ if (node == NULL)
+ goto restart;
+ shift -= RADIX_TREE_MAP_SHIFT;
+ offset = (index >> shift) & RADIX_TREE_MAP_MASK;
+ }
+
+ /* Update the iterator state */
+ iter->index = index;
+ iter->next_index = (index | RADIX_TREE_MAP_MASK) + 1;
+
+ /* Construct iter->tags bit-mask from node->tags[tag] array */
+ if (flags & RADIX_TREE_ITER_TAGGED) {
+ unsigned tag_long, tag_bit;
+
+ tag_long = offset / BITS_PER_LONG;
+ tag_bit = offset % BITS_PER_LONG;
+ iter->tags = node->tags[tag][tag_long] >> tag_bit;
+ /* This never happens if RADIX_TREE_TAG_LONGS == 1 */
+ if (tag_long < RADIX_TREE_TAG_LONGS - 1) {
+ /* Pick tags from next element */
+ if (tag_bit)
+ iter->tags |= node->tags[tag][tag_long + 1] <<
+ (BITS_PER_LONG - tag_bit);
+ /* Clip chunk size, here only BITS_PER_LONG tags */
+ iter->next_index = index + BITS_PER_LONG;
+ }
+ }
+
+ return node->slots + offset;
+}
+EXPORT_SYMBOL(radix_tree_next_chunk);
+
/**
* radix_tree_range_tag_if_tagged - for each item in given range set given
* tag if item has another tag set
projects / people / ms / linux.git / commitdiff
