+
+ /* Last level lookup succeded. We got an actual match. */
+ return (struct cds_ja_node *) node_flag;
+}
+
+static
+struct cds_ja_node *cds_ja_lookup_inequality(struct cds_ja *ja, uint64_t key,
+ uint64_t *result_key, enum ja_lookup_inequality mode)
+{
+ int tree_depth, level;
+ struct cds_ja_inode_flag *node_flag, *cur_node_depth[JA_MAX_DEPTH];
+ uint8_t cur_key[JA_MAX_DEPTH];
+ uint64_t _result_key = 0;
+ enum ja_direction dir;
+
+ switch (mode) {
+ case JA_LOOKUP_BE:
+ if (caa_unlikely(key > ja->key_max || key == 0))
+ return NULL;
+ break;
+ case JA_LOOKUP_AE:
+ if (caa_unlikely(key >= ja->key_max))
+ return NULL;
+ break;
+ default:
+ return NULL;
+ }
+
+ memset(cur_node_depth, 0, sizeof(cur_node_depth));
+ memset(cur_key, 0, sizeof(cur_key));
+ 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 NULL;
+
+ 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_key[level - 1] = iter_key;
+ cur_node_depth[level] = node_flag;
+ dbg_printf("cds_ja_lookup_inequality 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. */
+ if (result_key)
+ *result_key = key;
+ return (struct cds_ja_node *) node_flag;
+ }
+
+ /*
+ * Find highest value left/right of current node.
+ * Current node is cur_node_depth[level].
+ * Start at current level. If we cannot find any key left/right
+ * of ours, go one level up, seek highest value left/right of
+ * current (recursively), and when we find one, get the
+ * rightmost/leftmost child of its rightmost/leftmost child
+ * (recursively).
+ */
+ switch (mode) {
+ case JA_LOOKUP_BE:
+ dir = JA_LEFT;
+ break;
+ case JA_LOOKUP_AE:
+ dir = JA_RIGHT;
+ break;
+ default:
+ assert(0);
+ }
+ 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_leftright(cur_node_depth[level - 1],
+ iter_key, &cur_key[level - 1], dir);
+ dbg_printf("cds_ja_lookup_inequality find sibling from %u at %u finds node_flag %p\n",
+ (unsigned int) iter_key, (unsigned int) cur_key[level - 1],
+ node_flag);
+ /* If found left/right sibling, find rightmost/leftmost child. */
+ if (ja_node_ptr(node_flag))
+ break;
+ }
+
+ if (!level) {
+ /* Reached the root and could not find a left/right sibling. */
+ return NULL;
+ }
+
+ level++;
+
+ /*
+ * From this point, we are guaranteed to be able to find a
+ * "below than"/"above than" match. ja_attach_node() and
+ * ja_detach_node() both guarantee that it is not possible for a
+ * lookup to reach a dead-end.
+ */
+
+ /*
+ * Find rightmost/leftmost child of rightmost/leftmost child
+ * (recursively).
+ */
+ switch (mode) {
+ case JA_LOOKUP_BE:
+ dir = JA_RIGHTMOST;
+ break;
+ case JA_LOOKUP_AE:
+ dir = JA_LEFTMOST;
+ break;
+ default:
+ assert(0);
+ }
+ for (; level < tree_depth; level++) {
+ node_flag = ja_node_get_minmax(node_flag, &cur_key[level - 1], dir);
+ dbg_printf("cds_ja_lookup_inequality find minmax at %u finds node_flag %p\n",
+ (unsigned int) cur_key[level - 1],
+ node_flag);
+ if (!ja_node_ptr(node_flag))
+ break;
+ }
+
+ assert(level == tree_depth);
+
+ if (result_key) {
+ for (level = 1; level < tree_depth; level++) {
+ _result_key |= ((uint64_t) cur_key[level - 1])
+ << (JA_BITS_PER_BYTE * (tree_depth - level - 1));
+ }
+ *result_key = _result_key;
+ }
+ return (struct cds_ja_node *) node_flag;
+}
+
+struct cds_ja_node *cds_ja_lookup_below_equal(struct cds_ja *ja,
+ uint64_t key, uint64_t *result_key)
+{
+ dbg_printf("cds_ja_lookup_below_equal key %" PRIu64 "\n", key);
+ return cds_ja_lookup_inequality(ja, key, result_key, JA_LOOKUP_BE);
+}
+
+struct cds_ja_node *cds_ja_lookup_above_equal(struct cds_ja *ja,
+ uint64_t key, uint64_t *result_key)
+{
+ dbg_printf("cds_ja_lookup_above_equal key %" PRIu64 "\n", key);
+ return cds_ja_lookup_inequality(ja, key, result_key, JA_LOOKUP_AE);
+}
+
+/*
+ * We reached an unpopulated node. Create it and the children we need,
+ * and then attach the entire branch to the current node. This may
+ * trigger recompaction of the current node. Locks needed: node lock
+ * (for add), and, possibly, parent node lock (to update pointer due to
+ * node recompaction).
+ *
+ * First take node lock, check if recompaction is needed, then take
+ * parent lock (if needed). Then we can proceed to create the new
+ * branch. Publish the new branch, and release locks.
+ * TODO: we currently always take the parent lock even when not needed.
+ *
+ * ja_attach_node() ensures that a lookup will _never_ see a branch that
+ * leads to a dead-end: before attaching a branch, the entire content of
+ * the new branch is populated, thus creating a cluster, before
+ * attaching the cluster to the rest of the tree, thus making it visible
+ * to lookups.
+ */
+static
+int ja_attach_node(struct cds_ja *ja,
+ struct cds_ja_inode_flag **attach_node_flag_ptr,
+ struct cds_ja_inode_flag *attach_node_flag,
+ struct cds_ja_inode_flag *parent_attach_node_flag,
+ struct cds_ja_inode_flag **old_node_flag_ptr,
+ struct cds_ja_inode_flag *old_node_flag,
+ uint64_t key,
+ unsigned int level,
+ struct cds_ja_node *child_node)
+{
+ struct cds_ja_shadow_node *shadow_node = NULL,
+ *parent_shadow_node = NULL;
+ struct cds_ja_inode_flag *iter_node_flag, *iter_dest_node_flag;
+ int ret, i;
+ struct cds_ja_inode_flag *created_nodes[JA_MAX_DEPTH];
+ int nr_created_nodes = 0;
+
+ dbg_printf("Attach node at level %u (old_node_flag %p, attach_node_flag_ptr %p attach_node_flag %p, parent_attach_node_flag %p)\n",
+ level, old_node_flag, attach_node_flag_ptr, attach_node_flag, parent_attach_node_flag);
+
+ assert(!old_node_flag);
+ if (attach_node_flag) {
+ shadow_node = rcuja_shadow_lookup_lock(ja->ht, attach_node_flag);
+ if (!shadow_node) {
+ ret = -EAGAIN;
+ goto end;
+ }
+ }
+ if (parent_attach_node_flag) {
+ parent_shadow_node = rcuja_shadow_lookup_lock(ja->ht,
+ parent_attach_node_flag);
+ if (!parent_shadow_node) {
+ ret = -EAGAIN;
+ goto unlock_shadow;
+ }
+ }
+
+ if (old_node_flag_ptr && ja_node_ptr(*old_node_flag_ptr)) {
+ /*
+ * Target node has been updated between RCU lookup and
+ * lock acquisition. We need to re-try lookup and
+ * attach.
+ */
+ ret = -EAGAIN;
+ goto unlock_parent;
+ }
+
+ /*
+ * Perform a lookup query to handle the case where
+ * old_node_flag_ptr is NULL. We cannot use it to check if the
+ * node has been populated between RCU lookup and mutex
+ * acquisition.
+ */
+ if (!old_node_flag_ptr) {
+ uint8_t iter_key;
+ struct cds_ja_inode_flag *lookup_node_flag;
+ struct cds_ja_inode_flag **lookup_node_flag_ptr;
+
+ iter_key = (uint8_t) (key >> (JA_BITS_PER_BYTE * (ja->tree_depth - level)));
+ lookup_node_flag = ja_node_get_nth(attach_node_flag,
+ &lookup_node_flag_ptr,
+ iter_key);
+ if (lookup_node_flag) {
+ ret = -EEXIST;
+ goto unlock_parent;
+ }
+ }
+
+ if (attach_node_flag_ptr && ja_node_ptr(*attach_node_flag_ptr) !=
+ ja_node_ptr(attach_node_flag)) {
+ /*
+ * Target node has been updated between RCU lookup and
+ * lock acquisition. We need to re-try lookup and
+ * attach.
+ */
+ ret = -EAGAIN;
+ goto unlock_parent;
+ }
+
+ /* Create new branch, starting from bottom */
+ iter_node_flag = (struct cds_ja_inode_flag *) child_node;
+
+ for (i = ja->tree_depth - 1; i >= (int) level; i--) {
+ uint8_t iter_key;
+
+ iter_key = (uint8_t) (key >> (JA_BITS_PER_BYTE * (ja->tree_depth - i - 1)));
+ dbg_printf("branch creation level %d, key %u\n",
+ i, (unsigned int) iter_key);
+ iter_dest_node_flag = NULL;
+ ret = ja_node_set_nth(ja, &iter_dest_node_flag,
+ iter_key,
+ iter_node_flag,
+ NULL, i);
+ if (ret) {
+ dbg_printf("branch creation error %d\n", ret);
+ goto check_error;
+ }
+ created_nodes[nr_created_nodes++] = iter_dest_node_flag;
+ iter_node_flag = iter_dest_node_flag;
+ }
+ assert(level > 0);
+
+ /* Publish branch */
+ if (level == 1) {
+ /*
+ * Attaching to root node.
+ */
+ rcu_assign_pointer(ja->root, iter_node_flag);
+ } else {
+ uint8_t iter_key;
+
+ iter_key = (uint8_t) (key >> (JA_BITS_PER_BYTE * (ja->tree_depth - level)));
+ dbg_printf("publish branch at level %d, key %u\n",
+ level - 1, (unsigned int) iter_key);
+ /* We need to use set_nth on the previous level. */
+ iter_dest_node_flag = attach_node_flag;
+ ret = ja_node_set_nth(ja, &iter_dest_node_flag,
+ iter_key,
+ iter_node_flag,
+ shadow_node, level - 1);
+ if (ret) {
+ dbg_printf("branch publish error %d\n", ret);
+ goto check_error;
+ }
+ /*
+ * Attach branch
+ */
+ rcu_assign_pointer(*attach_node_flag_ptr, iter_dest_node_flag);
+ }
+
+ /* Success */
+ ret = 0;
+
+check_error:
+ if (ret) {
+ for (i = 0; i < nr_created_nodes; i++) {
+ int tmpret;
+ int flags;
+
+ flags = RCUJA_SHADOW_CLEAR_FREE_LOCK;
+ if (i)
+ flags |= RCUJA_SHADOW_CLEAR_FREE_NODE;
+ tmpret = rcuja_shadow_clear(ja->ht,
+ created_nodes[i],
+ NULL,
+ flags);
+ assert(!tmpret);
+ }
+ }
+unlock_parent:
+ if (parent_shadow_node)
+ rcuja_shadow_unlock(parent_shadow_node);
+unlock_shadow:
+ if (shadow_node)
+ rcuja_shadow_unlock(shadow_node);
+end:
+ return ret;
+}
+
+/*
+ * Lock the parent containing the pointer to list of duplicates, and add
+ * node to this list. Failure can happen if concurrent update changes
+ * the parent before we get the lock. We return -EAGAIN in that case.
+ * Return 0 on success, negative error value on failure.
+ */
+static
+int ja_chain_node(struct cds_ja *ja,
+ struct cds_ja_inode_flag *parent_node_flag,
+ struct cds_ja_inode_flag **node_flag_ptr,
+ struct cds_ja_inode_flag *node_flag,
+ struct cds_ja_node *last_node,
+ struct cds_ja_node *node)
+{
+ struct cds_ja_shadow_node *shadow_node;
+ struct cds_ja_node *iter_node;
+ int ret = 0, found = 0;
+
+ shadow_node = rcuja_shadow_lookup_lock(ja->ht, parent_node_flag);
+ if (!shadow_node) {
+ return -EAGAIN;
+ }
+ /*
+ * Ensure that previous node is still there at end of list.
+ */
+ iter_node = (struct cds_ja_node *) ja_node_ptr(node_flag);
+ if ((struct cds_ja_node *) ja_node_ptr(*node_flag_ptr) != iter_node) {
+ ret = -EAGAIN;
+ goto end;
+ }
+ cds_ja_for_each_duplicate(iter_node) {
+ if (iter_node == last_node)
+ found = 1;
+ }
+ if (!found) {
+ ret = -EAGAIN;
+ goto end;
+ }
+ /*
+ * Add node to tail of list to ensure that RCU traversals will
+ * always see either the prior node or the newly added if
+ * executed concurrently with a sequence of add followed by del
+ * on the same key. Safe against concurrent RCU read traversals.
+ */
+ node->next = NULL;
+ rcu_assign_pointer(last_node->next, node);
+end:
+ rcuja_shadow_unlock(shadow_node);
+ return ret;
+}
+
+static
+int _cds_ja_add(struct cds_ja *ja, uint64_t key,
+ struct cds_ja_node *node,
+ struct cds_ja_node **unique_node_ret)
+{
+ unsigned int tree_depth, i;
+ struct cds_ja_inode_flag *attach_node_flag,
+ *parent_node_flag,
+ *parent2_node_flag,
+ *node_flag,
+ *parent_attach_node_flag;
+ struct cds_ja_inode_flag **attach_node_flag_ptr,
+ **parent_node_flag_ptr,
+ **node_flag_ptr;
+ int ret;
+
+ if (caa_unlikely(key > ja->key_max)) {
+ return -EINVAL;
+ }
+ tree_depth = ja->tree_depth;
+
+retry:
+ dbg_printf("cds_ja_add attempt: key %" PRIu64 ", node %p\n",
+ key, node);
+ parent2_node_flag = NULL;
+ parent_node_flag =
+ (struct cds_ja_inode_flag *) &ja->root; /* Use root ptr address as key for mutex */
+ parent_node_flag_ptr = NULL;
+ node_flag = rcu_dereference(ja->root);
+ node_flag_ptr = &ja->root;
+
+ /* Iterate on all internal levels */
+ for (i = 1; i < tree_depth; i++) {
+ uint8_t iter_key;
+
+ if (!ja_node_ptr(node_flag))
+ break;
+ dbg_printf("cds_ja_add iter parent2_node_flag %p parent_node_flag %p node_flag_ptr %p node_flag %p\n",
+ parent2_node_flag, parent_node_flag, node_flag_ptr, node_flag);
+ iter_key = (uint8_t) (key >> (JA_BITS_PER_BYTE * (tree_depth - i - 1)));
+ parent2_node_flag = parent_node_flag;
+ parent_node_flag = node_flag;
+ parent_node_flag_ptr = node_flag_ptr;
+ node_flag = ja_node_get_nth(node_flag,
+ &node_flag_ptr,
+ iter_key);
+ }
+
+ /*
+ * We reached either bottom of tree or internal NULL node,
+ * simply add node to last internal level, or chain it if key is
+ * already present.
+ */
+ if (!ja_node_ptr(node_flag)) {
+ dbg_printf("cds_ja_add NULL parent2_node_flag %p parent_node_flag %p node_flag_ptr %p node_flag %p\n",
+ parent2_node_flag, parent_node_flag, node_flag_ptr, node_flag);
+
+ attach_node_flag = parent_node_flag;
+ attach_node_flag_ptr = parent_node_flag_ptr;
+ parent_attach_node_flag = parent2_node_flag;
+
+ ret = ja_attach_node(ja, attach_node_flag_ptr,
+ attach_node_flag,
+ parent_attach_node_flag,
+ node_flag_ptr,
+ node_flag,
+ key, i, node);
+ } else {
+ struct cds_ja_node *iter_node, *last_node = NULL;
+
+ if (unique_node_ret) {
+ *unique_node_ret = (struct cds_ja_node *) ja_node_ptr(node_flag);
+ return -EEXIST;
+ }
+
+ /* Find last duplicate */
+ iter_node = (struct cds_ja_node *) ja_node_ptr(node_flag);
+ cds_ja_for_each_duplicate_rcu(iter_node)
+ last_node = iter_node;
+
+ dbg_printf("cds_ja_add duplicate parent2_node_flag %p parent_node_flag %p node_flag_ptr %p node_flag %p\n",
+ parent2_node_flag, parent_node_flag, node_flag_ptr, node_flag);
+
+ attach_node_flag = node_flag;
+ attach_node_flag_ptr = node_flag_ptr;
+ parent_attach_node_flag = parent_node_flag;
+
+ ret = ja_chain_node(ja,
+ parent_attach_node_flag,
+ attach_node_flag_ptr,
+ attach_node_flag,
+ last_node,
+ node);
+ }
+ if (ret == -EAGAIN || ret == -EEXIST)
+ goto retry;
+
+ return ret;
+}
+
+int cds_ja_add(struct cds_ja *ja, uint64_t key,
+ struct cds_ja_node *node)
+{
+ return _cds_ja_add(ja, key, node, NULL);
+}
+
+struct cds_ja_node *cds_ja_add_unique(struct cds_ja *ja, uint64_t key,
+ struct cds_ja_node *node)
+{
+ int ret;
+ struct cds_ja_node *ret_node;
+
+ ret = _cds_ja_add(ja, key, node, &ret_node);
+ if (ret == -EEXIST)
+ return ret_node;
+ else
+ return node;
+}
+
+/*
+ * Note: there is no need to lookup the pointer address associated with
+ * each node's nth item after taking the lock: it's already been done by
+ * cds_ja_del while holding the rcu read-side lock, and our node rules
+ * ensure that when a match value -> pointer is found in a node, it is
+ * _NEVER_ changed for that node without recompaction, and recompaction
+ * reallocates the node.
+ * However, when a child is removed from "linear" nodes, its pointer
+ * is set to NULL. We therefore check, while holding the locks, if this
+ * pointer is NULL, and return -ENOENT to the caller if it is the case.
+ *
+ * ja_detach_node() ensures that a lookup will _never_ see a branch that
+ * leads to a dead-end: when removing branch, it makes sure to perform
+ * the "cut" at the highest node that has only one child, effectively
+ * replacing it with a NULL pointer.
+ */
+static
+int ja_detach_node(struct cds_ja *ja,
+ struct cds_ja_inode_flag **snapshot,
+ struct cds_ja_inode_flag ***snapshot_ptr,
+ uint8_t *snapshot_n,
+ int nr_snapshot,
+ uint64_t key,
+ struct cds_ja_node *node)
+{
+ struct cds_ja_shadow_node *shadow_nodes[JA_MAX_DEPTH];
+ struct cds_ja_inode_flag **node_flag_ptr = NULL,
+ *parent_node_flag = NULL,
+ **parent_node_flag_ptr = NULL;
+ struct cds_ja_inode_flag *iter_node_flag;
+ int ret, i, nr_shadow = 0, nr_clear = 0, nr_branch = 0;
+ uint8_t n = 0;
+
+ assert(nr_snapshot == ja->tree_depth + 1);
+
+ /*
+ * From the last internal level node going up, get the node
+ * lock, check if the node has only one child left. If it is the
+ * case, we continue iterating upward. When we reach a node
+ * which has more that one child left, we lock the parent, and
+ * proceed to the node deletion (removing its children too).
+ */
+ for (i = nr_snapshot - 2; i >= 1; i--) {
+ struct cds_ja_shadow_node *shadow_node;
+
+ shadow_node = rcuja_shadow_lookup_lock(ja->ht,
+ snapshot[i]);
+ if (!shadow_node) {
+ ret = -EAGAIN;
+ goto end;
+ }
+ shadow_nodes[nr_shadow++] = shadow_node;
+
+ /*
+ * Check if node has been removed between RCU
+ * lookup and lock acquisition.
+ */
+ assert(snapshot_ptr[i + 1]);
+ if (ja_node_ptr(*snapshot_ptr[i + 1])
+ != ja_node_ptr(snapshot[i + 1])) {
+ ret = -ENOENT;
+ goto end;
+ }
+
+ assert(shadow_node->nr_child > 0);
+ if (shadow_node->nr_child == 1 && i > 1)
+ nr_clear++;
+ nr_branch++;
+ if (shadow_node->nr_child > 1 || i == 1) {
+ /* Lock parent and break */
+ shadow_node = rcuja_shadow_lookup_lock(ja->ht,
+ snapshot[i - 1]);
+ if (!shadow_node) {
+ ret = -EAGAIN;
+ goto end;
+ }
+ shadow_nodes[nr_shadow++] = shadow_node;
+
+ /*
+ * Check if node has been removed between RCU
+ * lookup and lock acquisition.
+ */
+ assert(snapshot_ptr[i]);
+ if (ja_node_ptr(*snapshot_ptr[i])
+ != ja_node_ptr(snapshot[i])) {
+ ret = -ENOENT;
+ goto end;
+ }
+
+ node_flag_ptr = snapshot_ptr[i + 1];
+ n = snapshot_n[i + 1];
+ parent_node_flag_ptr = snapshot_ptr[i];
+ parent_node_flag = snapshot[i];
+
+ if (i > 1) {
+ /*
+ * Lock parent's parent, in case we need
+ * to recompact parent.
+ */
+ shadow_node = rcuja_shadow_lookup_lock(ja->ht,
+ snapshot[i - 2]);
+ if (!shadow_node) {
+ ret = -EAGAIN;
+ goto end;
+ }
+ shadow_nodes[nr_shadow++] = shadow_node;
+
+ /*
+ * Check if node has been removed between RCU
+ * lookup and lock acquisition.
+ */
+ assert(snapshot_ptr[i - 1]);
+ if (ja_node_ptr(*snapshot_ptr[i - 1])
+ != ja_node_ptr(snapshot[i - 1])) {
+ ret = -ENOENT;
+ goto end;
+ }
+ }
+
+ break;
+ }
+ }
+
+ /*
+ * At this point, we want to delete all nodes that are about to
+ * be removed from shadow_nodes (except the last one, which is
+ * either the root or the parent of the upmost node with 1
+ * child). OK to free lock here, because RCU read lock is held,
+ * and free only performed in call_rcu.
+ */
+
+ for (i = 0; i < nr_clear; i++) {
+ ret = rcuja_shadow_clear(ja->ht,
+ shadow_nodes[i]->node_flag,
+ shadow_nodes[i],
+ RCUJA_SHADOW_CLEAR_FREE_NODE
+ | RCUJA_SHADOW_CLEAR_FREE_LOCK);
+ assert(!ret);
+ }
+
+ iter_node_flag = parent_node_flag;
+ /* Remove from parent */
+ ret = ja_node_clear_ptr(ja,
+ node_flag_ptr, /* Pointer to location to nullify */
+ &iter_node_flag, /* Old new parent ptr in its parent */
+ shadow_nodes[nr_branch - 1], /* of parent */
+ n, nr_branch - 1);
+ if (ret)
+ goto end;
+
+ dbg_printf("ja_detach_node: publish %p instead of %p\n",
+ iter_node_flag, *parent_node_flag_ptr);
+ /* Update address of parent ptr in its parent */
+ rcu_assign_pointer(*parent_node_flag_ptr, iter_node_flag);
+
+end:
+ for (i = 0; i < nr_shadow; i++)
+ rcuja_shadow_unlock(shadow_nodes[i]);
+ return ret;
+}
+
+static
+int ja_unchain_node(struct cds_ja *ja,
+ struct cds_ja_inode_flag *parent_node_flag,
+ struct cds_ja_inode_flag **node_flag_ptr,
+ struct cds_ja_inode_flag *node_flag,
+ struct cds_ja_node *node)
+{
+ struct cds_ja_shadow_node *shadow_node;
+ struct cds_ja_node *iter_node, **iter_node_ptr, **prev_node_ptr = NULL;
+ int ret = 0, count = 0, found = 0;
+
+ shadow_node = rcuja_shadow_lookup_lock(ja->ht, parent_node_flag);
+ if (!shadow_node)
+ return -EAGAIN;
+ if (ja_node_ptr(*node_flag_ptr) != ja_node_ptr(node_flag)) {
+ ret = -EAGAIN;
+ goto end;
+ }
+ /*
+ * Find the previous node's next pointer pointing to our node,
+ * so we can update it. Retry if another thread removed all but
+ * one of duplicates since check (this check was performed
+ * without lock). Ensure that the node we are about to remove is
+ * still in the list (while holding lock). No need for RCU
+ * traversal here since we hold the lock on the parent.
+ */
+ iter_node_ptr = (struct cds_ja_node **) node_flag_ptr;
+ iter_node = (struct cds_ja_node *) ja_node_ptr(node_flag);
+ cds_ja_for_each_duplicate(iter_node) {
+ count++;
+ if (iter_node == node) {
+ prev_node_ptr = iter_node_ptr;
+ found++;
+ }
+ iter_node_ptr = &iter_node->next;
+ }
+ assert(found <= 1);
+ if (!found || count == 1) {
+ ret = -EAGAIN;
+ goto end;
+ }
+ CMM_STORE_SHARED(*prev_node_ptr, node->next);
+ /*
+ * Validate that we indeed removed the node from linked list.
+ */
+ assert(ja_node_ptr(*node_flag_ptr) != (struct cds_ja_inode *) node);
+end: