* x1: Value entry or tagged pointer
*
* Attempting to store internal entries in the XArray is a bug.
+ *
+ * Most internal entries are pointers to the next node in the tree.
+ * The following internal entries have a special meaning:
+ *
+ * 0-62: Sibling entries
+ * 256: Retry entry
*/
#define BITS_PER_XA_VALUE (BITS_PER_LONG - 1)
return (unsigned long)entry & 3UL;
}
+/*
+ * xa_mk_internal() - Create an internal entry.
+ * @v: Value to turn into an internal entry.
+ *
+ * Context: Any context.
+ * Return: An XArray internal entry corresponding to this value.
+ */
+static inline void *xa_mk_internal(unsigned long v)
+{
+ return (void *)((v << 2) | 2);
+}
+
+/*
+ * xa_to_internal() - Extract the value from an internal entry.
+ * @entry: XArray entry.
+ *
+ * Context: Any context.
+ * Return: The value which was stored in the internal entry.
+ */
+static inline unsigned long xa_to_internal(const void *entry)
+{
+ return (unsigned long)entry >> 2;
+}
+
+/*
+ * xa_is_internal() - Is the entry an internal entry?
+ * @entry: XArray entry.
+ *
+ * Context: Any context.
+ * Return: %true if the entry is an internal entry.
+ */
+static inline bool xa_is_internal(const void *entry)
+{
+ return ((unsigned long)entry & 3) == 2;
+}
+
#define xa_trylock(xa) spin_trylock(&(xa)->xa_lock)
#define xa_lock(xa) spin_lock(&(xa)->xa_lock)
#define xa_unlock(xa) spin_unlock(&(xa)->xa_lock)
#define xa_unlock_irqrestore(xa, flags) \
spin_unlock_irqrestore(&(xa)->xa_lock, flags)
+/* Everything below here is the Advanced API. Proceed with caution. */
+
+/*
+ * The xarray is constructed out of a set of 'chunks' of pointers. Choosing
+ * the best chunk size requires some tradeoffs. A power of two recommends
+ * itself so that we can walk the tree based purely on shifts and masks.
+ * Generally, the larger the better; as the number of slots per level of the
+ * tree increases, the less tall the tree needs to be. But that needs to be
+ * balanced against the memory consumption of each node. On a 64-bit system,
+ * xa_node is currently 576 bytes, and we get 7 of them per 4kB page. If we
+ * doubled the number of slots per node, we'd get only 3 nodes per 4kB page.
+ */
+#ifndef XA_CHUNK_SHIFT
+#define XA_CHUNK_SHIFT (CONFIG_BASE_SMALL ? 4 : 6)
+#endif
+#define XA_CHUNK_SIZE (1UL << XA_CHUNK_SHIFT)
+#define XA_CHUNK_MASK (XA_CHUNK_SIZE - 1)
+
+/* Private */
+static inline bool xa_is_node(const void *entry)
+{
+ return xa_is_internal(entry) && (unsigned long)entry > 4096;
+}
+
+/* Private */
+static inline void *xa_mk_sibling(unsigned int offset)
+{
+ return xa_mk_internal(offset);
+}
+
+/* Private */
+static inline unsigned long xa_to_sibling(const void *entry)
+{
+ return xa_to_internal(entry);
+}
+
+/**
+ * xa_is_sibling() - Is the entry a sibling entry?
+ * @entry: Entry retrieved from the XArray
+ *
+ * Return: %true if the entry is a sibling entry.
+ */
+static inline bool xa_is_sibling(const void *entry)
+{
+ return IS_ENABLED(CONFIG_XARRAY_MULTI) && xa_is_internal(entry) &&
+ (entry < xa_mk_sibling(XA_CHUNK_SIZE - 1));
+}
+
+#define XA_RETRY_ENTRY xa_mk_internal(256)
+
#endif /* _LINUX_XARRAY_H */
#include <linux/rcupdate.h>
#include <linux/slab.h>
#include <linux/string.h>
+#include <linux/xarray.h>
/* Number of nodes in fully populated tree of given height */
return (void *)((unsigned long)ptr | RADIX_TREE_INTERNAL_NODE);
}
-#define RADIX_TREE_RETRY node_to_entry(NULL)
-
-#ifdef CONFIG_RADIX_TREE_MULTIORDER
-/* Sibling slots point directly to another slot in the same node */
-static inline
-bool is_sibling_entry(const struct radix_tree_node *parent, void *node)
-{
- void __rcu **ptr = node;
- return (parent->slots <= ptr) &&
- (ptr < parent->slots + RADIX_TREE_MAP_SIZE);
-}
-#else
-static inline
-bool is_sibling_entry(const struct radix_tree_node *parent, void *node)
-{
- return false;
-}
-#endif
+#define RADIX_TREE_RETRY XA_RETRY_ENTRY
static inline unsigned long
get_slot_offset(const struct radix_tree_node *parent, void __rcu **slot)
unsigned int offset = (index >> parent->shift) & RADIX_TREE_MAP_MASK;
void __rcu **entry = rcu_dereference_raw(parent->slots[offset]);
-#ifdef CONFIG_RADIX_TREE_MULTIORDER
- if (radix_tree_is_internal_node(entry)) {
- if (is_sibling_entry(parent, entry)) {
- void __rcu **sibentry;
- sibentry = (void __rcu **) entry_to_node(entry);
- offset = get_slot_offset(parent, sibentry);
- entry = rcu_dereference_raw(*sibentry);
- }
+ if (xa_is_sibling(entry)) {
+ offset = xa_to_sibling(entry);
+ entry = rcu_dereference_raw(parent->slots[offset]);
}
-#endif
*nodep = (void *)entry;
return offset;
} else if (!radix_tree_is_internal_node(entry)) {
pr_debug("radix entry %p offset %ld indices %lu-%lu parent %p\n",
entry, i, first, last, node);
- } else if (is_sibling_entry(node, entry)) {
+ } else if (xa_is_sibling(entry)) {
pr_debug("radix sblng %p offset %ld indices %lu-%lu parent %p val %p\n",
entry, i, first, last, node,
- *(void **)entry_to_node(entry));
+ node->slots[xa_to_sibling(entry)]);
} else {
dump_node(entry_to_node(entry), first);
}
for (;;) {
void *entry = rcu_dereference_raw(child->slots[offset]);
- if (radix_tree_is_internal_node(entry) && child->shift &&
- !is_sibling_entry(child, entry)) {
+ if (xa_is_node(entry) && child->shift) {
child = entry_to_node(entry);
offset = 0;
continue;
static inline int insert_entries(struct radix_tree_node *node,
void __rcu **slot, void *item, unsigned order, bool replace)
{
- struct radix_tree_node *child;
+ void *sibling;
unsigned i, n, tag, offset, tags = 0;
if (node) {
offset = offset & ~(n - 1);
slot = &node->slots[offset];
}
- child = node_to_entry(slot);
+ sibling = xa_mk_sibling(offset);
for (i = 0; i < n; i++) {
if (slot[i]) {
for (i = 0; i < n; i++) {
struct radix_tree_node *old = rcu_dereference_raw(slot[i]);
if (i) {
- rcu_assign_pointer(slot[i], child);
+ rcu_assign_pointer(slot[i], sibling);
for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++)
if (tags & (1 << tag))
tag_clear(node, tag, offset + i);
if (tags & (1 << tag))
tag_set(node, tag, offset);
}
- if (radix_tree_is_internal_node(old) &&
- !is_sibling_entry(node, old) &&
- (old != RADIX_TREE_RETRY))
+ if (xa_is_node(old))
radix_tree_free_nodes(old);
if (xa_is_value(old))
node->exceptional--;
void __rcu **slot, int count, int exceptional)
{
#ifdef CONFIG_RADIX_TREE_MULTIORDER
- void *ptr = node_to_entry(slot);
- unsigned offset = get_slot_offset(node, slot) + 1;
+ unsigned offset = get_slot_offset(node, slot);
+ void *ptr = xa_mk_sibling(offset);
- while (offset < RADIX_TREE_MAP_SIZE) {
+ while (++offset < RADIX_TREE_MAP_SIZE) {
if (rcu_dereference_raw(node->slots[offset]) != ptr)
break;
if (count < 0) {
node->count--;
}
node->exceptional += exceptional;
- offset++;
}
#endif
}
tags |= 1 << tag;
for (end = offset + 1; end < RADIX_TREE_MAP_SIZE; end++) {
- if (!is_sibling_entry(parent,
- rcu_dereference_raw(parent->slots[end])))
+ if (!xa_is_sibling(rcu_dereference_raw(parent->slots[end])))
break;
for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++)
if (tags & (1 << tag))
{
while (iter->index < iter->next_index) {
*nodep = rcu_dereference_raw(*slot);
- if (*nodep && !is_sibling_entry(iter->node, *nodep))
+ if (*nodep && !xa_is_sibling(*nodep))
return slot;
slot++;
iter->index = __radix_tree_iter_add(iter, 1);
while (++offset < RADIX_TREE_MAP_SIZE) {
void *slot = rcu_dereference_raw(
node->slots[offset]);
- if (is_sibling_entry(node, slot))
+ if (xa_is_sibling(slot))
continue;
if (slot)
break;
BUILD_BUG_ON(RADIX_TREE_MAX_TAGS + __GFP_BITS_SHIFT > 32);
BUILD_BUG_ON(ROOT_IS_IDR & ~GFP_ZONEMASK);
+ BUILD_BUG_ON(XA_CHUNK_SIZE > 255);
radix_tree_node_cachep = kmem_cache_create("radix_tree_node",
sizeof(struct radix_tree_node), 0,
SLAB_PANIC | SLAB_RECLAIM_ACCOUNT,
projects / openwrt / staging / blogic.git / commitdiff