Commit 0ac398ef authored by Matthew Wilcox's avatar Matthew Wilcox

radix-tree: Add radix_tree_iter_delete

Factor the deletion code out into __radix_tree_delete() and provide a
nice iterator-based wrapper around it.  If we free the node, advance
the iterator to avoid reading from freed memory.
Signed-off-by: default avatarMatthew Wilcox <mawilcox@microsoft.com>
parent 30b888ba
...@@ -311,6 +311,8 @@ void __radix_tree_delete_node(struct radix_tree_root *root, ...@@ -311,6 +311,8 @@ void __radix_tree_delete_node(struct radix_tree_root *root,
struct radix_tree_node *node, struct radix_tree_node *node,
radix_tree_update_node_t update_node, radix_tree_update_node_t update_node,
void *private); void *private);
void radix_tree_iter_delete(struct radix_tree_root *,
struct radix_tree_iter *iter, void **slot);
void *radix_tree_delete_item(struct radix_tree_root *, unsigned long, void *); void *radix_tree_delete_item(struct radix_tree_root *, unsigned long, void *);
void *radix_tree_delete(struct radix_tree_root *, unsigned long); void *radix_tree_delete(struct radix_tree_root *, unsigned long);
void radix_tree_clear_tags(struct radix_tree_root *root, void radix_tree_clear_tags(struct radix_tree_root *root,
......
...@@ -581,10 +581,12 @@ static int radix_tree_extend(struct radix_tree_root *root, ...@@ -581,10 +581,12 @@ static int radix_tree_extend(struct radix_tree_root *root,
* radix_tree_shrink - shrink radix tree to minimum height * radix_tree_shrink - shrink radix tree to minimum height
* @root radix tree root * @root radix tree root
*/ */
static inline void radix_tree_shrink(struct radix_tree_root *root, static inline bool radix_tree_shrink(struct radix_tree_root *root,
radix_tree_update_node_t update_node, radix_tree_update_node_t update_node,
void *private) void *private)
{ {
bool shrunk = false;
for (;;) { for (;;) {
struct radix_tree_node *node = root->rnode; struct radix_tree_node *node = root->rnode;
struct radix_tree_node *child; struct radix_tree_node *child;
...@@ -645,20 +647,26 @@ static inline void radix_tree_shrink(struct radix_tree_root *root, ...@@ -645,20 +647,26 @@ static inline void radix_tree_shrink(struct radix_tree_root *root,
WARN_ON_ONCE(!list_empty(&node->private_list)); WARN_ON_ONCE(!list_empty(&node->private_list));
radix_tree_node_free(node); radix_tree_node_free(node);
shrunk = true;
} }
return shrunk;
} }
static void delete_node(struct radix_tree_root *root, static bool delete_node(struct radix_tree_root *root,
struct radix_tree_node *node, struct radix_tree_node *node,
radix_tree_update_node_t update_node, void *private) radix_tree_update_node_t update_node, void *private)
{ {
bool deleted = false;
do { do {
struct radix_tree_node *parent; struct radix_tree_node *parent;
if (node->count) { if (node->count) {
if (node == entry_to_node(root->rnode)) if (node == entry_to_node(root->rnode))
radix_tree_shrink(root, update_node, private); deleted |= radix_tree_shrink(root, update_node,
return; private);
return deleted;
} }
parent = node->parent; parent = node->parent;
...@@ -672,9 +680,12 @@ static void delete_node(struct radix_tree_root *root, ...@@ -672,9 +680,12 @@ static void delete_node(struct radix_tree_root *root,
WARN_ON_ONCE(!list_empty(&node->private_list)); WARN_ON_ONCE(!list_empty(&node->private_list));
radix_tree_node_free(node); radix_tree_node_free(node);
deleted = true;
node = parent; node = parent;
} while (node); } while (node);
return deleted;
} }
/** /**
...@@ -1859,25 +1870,55 @@ void __radix_tree_delete_node(struct radix_tree_root *root, ...@@ -1859,25 +1870,55 @@ void __radix_tree_delete_node(struct radix_tree_root *root,
delete_node(root, node, update_node, private); delete_node(root, node, update_node, private);
} }
static bool __radix_tree_delete(struct radix_tree_root *root,
struct radix_tree_node *node, void **slot)
{
unsigned offset = get_slot_offset(node, slot);
int tag;
for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++)
node_tag_clear(root, node, tag, offset);
replace_slot(root, node, slot, NULL, true);
return node && delete_node(root, node, NULL, NULL);
}
/** /**
* radix_tree_delete_item - delete an item from a radix tree * radix_tree_iter_delete - delete the entry at this iterator position
* @root: radix tree root * @root: radix tree root
* @index: index key * @iter: iterator state
* @item: expected item * @slot: pointer to slot
* *
* Remove @item at @index from the radix tree rooted at @root. * Delete the entry at the position currently pointed to by the iterator.
* This may result in the current node being freed; if it is, the iterator
* is advanced so that it will not reference the freed memory. This
* function may be called without any locking if there are no other threads
* which can access this tree.
*/
void radix_tree_iter_delete(struct radix_tree_root *root,
struct radix_tree_iter *iter, void **slot)
{
if (__radix_tree_delete(root, iter->node, slot))
iter->index = iter->next_index;
}
/**
* radix_tree_delete_item - delete an item from a radix tree
* @root: radix tree root
* @index: index key
* @item: expected item
*
* Remove @item at @index from the radix tree rooted at @root.
* *
* Returns the address of the deleted item, or NULL if it was not present * Return: the deleted entry, or %NULL if it was not present
* or the entry at the given @index was not @item. * or the entry at the given @index was not @item.
*/ */
void *radix_tree_delete_item(struct radix_tree_root *root, void *radix_tree_delete_item(struct radix_tree_root *root,
unsigned long index, void *item) unsigned long index, void *item)
{ {
struct radix_tree_node *node; struct radix_tree_node *node;
unsigned int offset;
void **slot; void **slot;
void *entry; void *entry;
int tag;
entry = __radix_tree_lookup(root, index, &node, &slot); entry = __radix_tree_lookup(root, index, &node, &slot);
if (!entry) if (!entry)
...@@ -1886,32 +1927,20 @@ void *radix_tree_delete_item(struct radix_tree_root *root, ...@@ -1886,32 +1927,20 @@ void *radix_tree_delete_item(struct radix_tree_root *root,
if (item && entry != item) if (item && entry != item)
return NULL; return NULL;
if (!node) { __radix_tree_delete(root, node, slot);
root_tag_clear_all(root);
root->rnode = NULL;
return entry;
}
offset = get_slot_offset(node, slot);
/* Clear all tags associated with the item to be deleted. */
for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++)
node_tag_clear(root, node, tag, offset);
__radix_tree_replace(root, node, slot, NULL, NULL, NULL);
return entry; return entry;
} }
EXPORT_SYMBOL(radix_tree_delete_item); EXPORT_SYMBOL(radix_tree_delete_item);
/** /**
* radix_tree_delete - delete an item from a radix tree * radix_tree_delete - delete an entry from a radix tree
* @root: radix tree root * @root: radix tree root
* @index: index key * @index: index key
* *
* Remove the item at @index from the radix tree rooted at @root. * Remove the entry at @index from the radix tree rooted at @root.
* *
* Returns the address of the deleted item, or NULL if it was not present. * Return: The deleted entry, or %NULL if it was not present.
*/ */
void *radix_tree_delete(struct radix_tree_root *root, unsigned long index) void *radix_tree_delete(struct radix_tree_root *root, unsigned long index)
{ {
......
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