struct cds_ja_inode_flag **node_flag_ptr)
{
assert(type->type_class == RCU_JA_PIGEON);
+ dbg_printf("ja_pigeon_node_clear_ptr: clearing ptr: %p\n", *node_flag_ptr);
rcu_assign_pointer(*node_flag_ptr, NULL);
shadow_node->nr_child--;
return 0;
}
skip_copy:
- if (JA_RECOMPACT_ADD) {
+ if (mode == JA_RECOMPACT_ADD) {
/* add node */
ret = _ja_node_set_nth(new_type, new_node,
new_shadow_node,
}
}
+ if (*node_flag_ptr != NULL) {
+ /*
+ * Attach point is non-NULL: it 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 */
CDS_INIT_HLIST_HEAD(&head);
cds_hlist_add_head_rcu(&child_node->list, &head);
assert(!tmpret);
}
}
+unlock_parent:
if (parent_shadow_node)
rcuja_shadow_unlock(parent_shadow_node);
unlock_shadow:
struct cds_ja_shadow_node *shadow_node;
shadow_node = rcuja_shadow_lookup_lock(ja->ht, parent_node_flag);
- if (!shadow_node)
+ if (!shadow_node) {
+ dbg_printf("AGAIN3\n");
return -EAGAIN;
+ }
cds_hlist_add_head_rcu(&node->list, head);
rcuja_shadow_unlock(shadow_node);
return 0;
*parent2_node_flag;
int ret;
- if (caa_unlikely(key > ja->key_max))
+ if (caa_unlikely(key > ja->key_max)) {
return -EINVAL;
+ }
tree_depth = ja->tree_depth;
retry:
(struct cds_hlist_head *) node_flag_ptr,
new_node);
}
- if (ret == -EAGAIN)
+ if (ret == -EAGAIN || ret == -EEXIST)
goto retry;
end:
return ret;
* 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.
*/
static
int ja_detach_node(struct cds_ja *ja,
*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;
- uint8_t n;
+ int ret, i, nr_shadow = 0, nr_clear = 0, nr_branch = 0;
+ uint8_t n = 0;
- assert(nr_snapshot == ja->tree_depth - 1);
+ assert(nr_snapshot == ja->tree_depth + 1);
/*
* From the last internal level node going up, get the 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 - 1; i >= 1; i--) {
+ for (i = nr_snapshot - 2; i >= 1; i--) {
struct cds_ja_shadow_node *shadow_node;
shadow_node = rcuja_shadow_lookup_lock(ja->ht,
}
assert(shadow_node->nr_child > 0);
shadow_nodes[nr_shadow++] = shadow_node;
- nr_clear++;
- if (i == nr_snapshot - 1) {
- /*
- * Re-check that last internal node level has
- * only one child, else trigger a retry.
- */
- if (shadow_node->nr_child != 1) {
- ret = -EAGAIN;
- goto end;
- }
- }
+ if (shadow_node->nr_child == 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,
goto end;
}
shadow_nodes[nr_shadow++] = shadow_node;
- node_flag_ptr = snapshot_ptr[i];
- n = snapshot_n[i];
- parent_node_flag_ptr = snapshot_ptr[i - 1];
- parent_node_flag = snapshot[i - 1];
+ 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
}
/*
- * At this point, we want to delete all nodes in shadow_nodes
- * (except the last one, which is either the root or the parent
- * of the upmost node with 1 child). OK to as to free lock here,
- * because RCU read lock is held, and free only performed in
- * call_rcu.
+ * Check if node has been removed between RCU lookup and lock
+ * acquisition.
+ */
+ if (!*node_flag_ptr) {
+ ret = -ENOENT;
+ goto end;
+ }
+
+ /*
+ * 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 as 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 = 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_clear], /* of parent */
+ shadow_nodes[nr_branch - 1], /* of parent */
n);
+ 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);
static
int ja_unchain_node(struct cds_ja *ja,
struct cds_ja_inode_flag *parent_node_flag,
+ struct cds_hlist_head *head,
struct cds_ja_node *node)
{
struct cds_ja_shadow_node *shadow_node;
- int ret = 0;
+ struct cds_hlist_node *hlist_node;
+ int ret = 0, count = 0;
shadow_node = rcuja_shadow_lookup_lock(ja->ht, parent_node_flag);
if (!shadow_node)
return -EAGAIN;
/*
* Retry if another thread removed all but one of duplicates
- * since check.
+ * since check (that was performed without lock).
*/
- if (shadow_node->nr_child == 1) {
+ cds_hlist_for_each_rcu(hlist_node, head, list) {
+ count++;
+ }
+
+ if (count == 1) {
ret = -EAGAIN;
goto end;
}
uint8_t snapshot_n[JA_MAX_DEPTH];
struct cds_ja_inode_flag *node_flag;
struct cds_ja_inode_flag **prev_node_flag_ptr;
- int nr_snapshot = 0;
+ int nr_snapshot;
int ret;
if (caa_unlikely(key > ja->key_max))
tree_depth = ja->tree_depth;
retry:
+ nr_snapshot = 0;
dbg_printf("cds_ja_del attempt: key %" PRIu64 ", node %p\n",
key, node);
/* snapshot for level 0 is only for shadow node lookup */
- snapshot_n[nr_snapshot] = 0;
+ snapshot_n[0] = 0;
+ snapshot_n[1] = 0;
snapshot_ptr[nr_snapshot] = NULL;
snapshot[nr_snapshot++] = (struct cds_ja_inode_flag *) &ja->root;
node_flag = rcu_dereference(ja->root);
return -ENOENT;
}
iter_key = (uint8_t) (key >> (JA_BITS_PER_BYTE * (tree_depth - i - 1)));
- if (nr_snapshot <= 1)
- snapshot_n[nr_snapshot] = 0;
- else
- snapshot_n[nr_snapshot - 1] = iter_key;
-
+ snapshot_n[nr_snapshot + 1] = iter_key;
snapshot_ptr[nr_snapshot] = prev_node_flag_ptr;
snapshot[nr_snapshot++] = node_flag;
node_flag = ja_node_get_nth(node_flag,
* to remove. Fail if we cannot find it.
*/
if (!ja_node_ptr(node_flag)) {
+ dbg_printf("cds_ja_del: no node found for key %" PRIu64 "\n",
+ key);
return -ENOENT;
} else {
- struct cds_hlist_head *hlist_head;
+ struct cds_hlist_head hlist_head;
struct cds_hlist_node *hlist_node;
struct cds_ja_node *entry, *match = NULL;
int count = 0;
- hlist_head = (struct cds_hlist_head *) ja_node_ptr(node_flag);
+ hlist_head.next =
+ (struct cds_hlist_node *) ja_node_ptr(node_flag);
cds_hlist_for_each_entry_rcu(entry,
hlist_node,
- hlist_head,
+ &hlist_head,
list) {
+ dbg_printf("cds_ja_del: compare %p with entry %p\n", node, entry);
if (entry == node)
match = entry;
count++;
}
- if (!match)
+ if (!match) {
+ dbg_printf("cds_ja_del: no node match for node %p key %" PRIu64 "\n", node, key);
return -ENOENT;
+ }
assert(count > 0);
if (count == 1) {
/*
- * Removing last of duplicates.
+ * Removing last of duplicates. Last snapshot
+ * does not have a shadow node (external leafs).
*/
snapshot_ptr[nr_snapshot] = prev_node_flag_ptr;
snapshot[nr_snapshot++] = node_flag;
ret = ja_detach_node(ja, snapshot, snapshot_ptr,
snapshot_n, nr_snapshot, key, node);
} else {
- ret = ja_unchain_node(ja, node_flag, entry);
+ ret = ja_unchain_node(ja, snapshot[nr_snapshot - 1],
+ &hlist_head, match);
}
}
- if (ret == -EAGAIN)
+ /*
+ * Explanation of -ENOENT handling: caused by concurrent delete
+ * between RCU lookup and actual removal. Need to re-do the
+ * lookup and removal attempt.
+ */
+ if (ret == -EAGAIN || ret == -ENOENT)
goto retry;
return ret;
}
switch (key_bits) {
case 8:
- ja->key_max = UINT8_MAX;
- break;
case 16:
- ja->key_max = UINT16_MAX;
- break;
+ case 24:
case 32:
- ja->key_max = UINT32_MAX;
+ case 40:
+ case 48:
+ case 56:
+ ja->key_max = (1ULL << key_bits) - 1;
break;
case 64:
ja->key_max = UINT64_MAX;
projects / urcu.git / blobdiff