#include <stdint.h>
#include "rcuja-internal.h"
-#include "bitfield.h"
#ifndef abs
#define abs_int(a) ((int) (a) > 0 ? (int) (a) : -((int) (a)))
return ptr;
}
+static
+struct cds_ja_inode_flag *ja_linear_node_get_left(const struct cds_ja_type *type,
+ struct cds_ja_inode *node,
+ unsigned int n)
+{
+ uint8_t nr_child;
+ uint8_t *values;
+ struct cds_ja_inode_flag **pointers;
+ struct cds_ja_inode_flag *ptr;
+ unsigned int i, match_idx;
+ int match_v = -1;
+
+ assert(type->type_class == RCU_JA_LINEAR || type->type_class == RCU_JA_POOL);
+
+ nr_child = ja_linear_node_get_nr_child(type, node);
+ cmm_smp_rmb(); /* read nr_child before values and pointers */
+ assert(nr_child <= type->max_linear_child);
+ assert(type->type_class != RCU_JA_LINEAR || nr_child >= type->min_child);
+
+ values = &node->u.data[1];
+ for (i = 0; i < nr_child; i++) {
+ unsigned int v;
+
+ v = CMM_LOAD_SHARED(values[i]);
+ if (v < n && (int) v > match_v) {
+ match_v = v;
+ match_idx = i;
+ }
+ }
+ if (match_v < 0) {
+ return NULL;
+ }
+ pointers = (struct cds_ja_inode_flag **) align_ptr_size(&values[type->max_linear_child]);
+ ptr = rcu_dereference(pointers[match_idx]);
+ return ptr;
+}
+
static
void ja_linear_node_get_ith_pos(const struct cds_ja_type *type,
struct cds_ja_inode *node,
&node->u.data[(unsigned int) i << type->pool_size_order];
}
+static
+struct cds_ja_inode_flag *ja_pool_node_get_left(const struct cds_ja_type *type,
+ struct cds_ja_inode *node,
+ unsigned int n)
+{
+ unsigned int pool_nr;
+ int match_v = -1;
+ struct cds_ja_inode_flag *match_node_flag = NULL;
+
+ assert(type->type_class == RCU_JA_POOL);
+
+ for (pool_nr = 0; pool_nr < (1U << type->nr_pool_order); pool_nr++) {
+ struct cds_ja_inode *pool =
+ ja_pool_node_get_ith_pool(type,
+ node, pool_nr);
+ uint8_t nr_child =
+ ja_linear_node_get_nr_child(type, pool);
+ unsigned int j;
+
+ for (j = 0; j < nr_child; j++) {
+ struct cds_ja_inode_flag *iter;
+ uint8_t v;
+
+ ja_linear_node_get_ith_pos(type, pool,
+ j, &v, &iter);
+ if (!iter)
+ continue;
+ if (v < n && (int) v > match_v) {
+ match_v = v;
+ match_node_flag = iter;
+ }
+ }
+ }
+ return match_node_flag;
+}
+
static
struct cds_ja_inode_flag *ja_pigeon_node_get_nth(const struct cds_ja_type *type,
struct cds_ja_inode *node,
return child_node_flag;
}
+static
+struct cds_ja_inode_flag *ja_pigeon_node_get_left(const struct cds_ja_type *type,
+ struct cds_ja_inode *node,
+ unsigned int n)
+{
+ struct cds_ja_inode_flag **child_node_flag_ptr;
+ struct cds_ja_inode_flag *child_node_flag;
+ int i;
+
+ assert(type->type_class == RCU_JA_PIGEON);
+
+ /* n - 1 is first value left of n */
+ for (i = n - 1; i >= 0; i--) {
+ child_node_flag_ptr = &((struct cds_ja_inode_flag **) node->u.data)[i];
+ child_node_flag = rcu_dereference(*child_node_flag_ptr);
+ if (child_node_flag) {
+ dbg_printf("ja_pigeon_node_get_left child_node_flag %p\n",
+ child_node_flag);
+ return child_node_flag;
+ }
+ }
+ return NULL;
+}
+
static
struct cds_ja_inode_flag *ja_pigeon_node_get_ith_pos(const struct cds_ja_type *type,
struct cds_ja_inode *node,
}
}
+static
+struct cds_ja_inode_flag *ja_node_get_left(struct cds_ja_inode_flag *node_flag,
+ unsigned int n)
+{
+ unsigned int type_index;
+ struct cds_ja_inode *node;
+ const struct cds_ja_type *type;
+
+ node = ja_node_ptr(node_flag);
+ assert(node != NULL);
+ type_index = ja_node_type(node_flag);
+ type = &ja_types[type_index];
+
+ switch (type->type_class) {
+ case RCU_JA_LINEAR:
+ return ja_linear_node_get_left(type, node, n);
+ case RCU_JA_POOL:
+ return ja_pool_node_get_left(type, node, n);
+ case RCU_JA_PIGEON:
+ return ja_pigeon_node_get_left(type, node, n);
+ default:
+ assert(0);
+ return (void *) -1UL;
+ }
+}
+
+static
+struct cds_ja_inode_flag *ja_node_get_rightmost(struct cds_ja_inode_flag *node_flag)
+{
+ return ja_node_get_left(node_flag, JA_ENTRY_PER_NODE);
+}
+
static
int ja_linear_node_set_nth(const struct cds_ja_type *type,
struct cds_ja_inode *node,
return head;
}
+/*
+ * cds_ja_lookup_lower_equal() may need to retry if a concurrent removal
+ * causes failure to find the previous node.
+ */
+struct cds_hlist_head cds_ja_lookup_lower_equal(struct cds_ja *ja, uint64_t key)
+{
+ int tree_depth, level;
+ struct cds_ja_inode_flag *node_flag, *cur_node_depth[JA_MAX_DEPTH];
+ struct cds_hlist_head head = { NULL };
+
+ if (caa_unlikely(key > ja->key_max || !key))
+ return head;
+
+retry:
+ memset(cur_node_depth, 0, sizeof(cur_node_depth));
+ tree_depth = ja->tree_depth;
+ node_flag = rcu_dereference(ja->root);
+ cur_node_depth[0] = node_flag;
+
+ /* level 0: root node */
+ if (!ja_node_ptr(node_flag))
+ return head;
+
+ for (level = 1; level < tree_depth; level++) {
+ uint8_t iter_key;
+
+ iter_key = (uint8_t) (key >> (JA_BITS_PER_BYTE * (tree_depth - level - 1)));
+ node_flag = ja_node_get_nth(node_flag, NULL, iter_key);
+ if (!ja_node_ptr(node_flag))
+ break;
+ cur_node_depth[level] = node_flag;
+ dbg_printf("cds_ja_lookup iter key lookup %u finds node_flag %p\n",
+ (unsigned int) iter_key, node_flag);
+ }
+
+ if (level == tree_depth) {
+ /* Last level lookup succeded. We got an equal match. */
+ head.next = (struct cds_hlist_node *) node_flag;
+ return head;
+ }
+
+ /*
+ * Find highest value left of current node.
+ * Current node is cur_node_depth[level].
+ * Start at current level. If we cannot find any key left of
+ * ours, go one level up, seek highest value left of current
+ * (recursively), and when we find one, get the rightmost child
+ * of its rightmost child (recursively).
+ */
+ for (; level > 0; level--) {
+ uint8_t iter_key;
+
+ iter_key = (uint8_t) (key >> (JA_BITS_PER_BYTE * (tree_depth - level - 1)));
+ node_flag = ja_node_get_left(cur_node_depth[level - 1],
+ iter_key);
+ /* If found left sibling, find rightmost child. */
+ if (ja_node_ptr(node_flag))
+ break;
+ }
+
+ if (!level) {
+ /* Reached the root and could not find a left sibling. */
+ return head;
+ }
+
+ level++;
+
+ /*
+ * From this point, we should be able to find a "lower than"
+ * match. The only reason why we could fail to find such a match
+ * would be due to a concurrent removal of the branch that
+ * contains the match. If this happens, we have no choice but to
+ * retry the entire lookup. Indeed, just because we reached a
+ * dead-end due to concurrent removal of the branch does not
+ * mean that other match don't exist. However, this requires
+ * going up into the tree, hence the retry.
+ */
+
+ /* Find rightmost child of rightmost child (recursively). */
+ for (; level < tree_depth; level++) {
+ node_flag = ja_node_get_rightmost(node_flag);
+ /* If found left sibling, find rightmost child. */
+ if (!ja_node_ptr(node_flag))
+ break;
+ }
+
+ if (level != tree_depth) {
+ /*
+ * We did not get a match. Caused by concurrent removal.
+ * We need to retry the entire lookup.
+ */
+ goto retry;
+ }
+
+ /* Last level lookup succeded. We got a "lower than" match. */
+ head.next = (struct cds_hlist_node *) node_flag;
+ return head;
+}
+
/*
* We reached an unpopulated node. Create it and the children we need,
* and then attach the entire branch to the current node. This may
projects / userspace-rcu.git / blobdiff