struct cds_ja_inode_flag *ja_linear_node_get_nth(const struct cds_ja_type *type,
struct cds_ja_inode *node,
struct cds_ja_inode_flag ***child_node_flag_ptr,
+ struct cds_ja_inode_flag **child_node_flag_v,
+ struct cds_ja_inode_flag ***node_flag_ptr,
uint8_t n)
{
uint8_t nr_child;
if (CMM_LOAD_SHARED(values[i]) == n)
break;
}
- if (i >= nr_child)
+ if (i >= nr_child) {
+ if (caa_unlikely(node_flag_ptr))
+ *node_flag_ptr = NULL;
return NULL;
+ }
pointers = (struct cds_ja_inode_flag **) align_ptr_size(&values[type->max_linear_child]);
ptr = rcu_dereference(pointers[i]);
if (caa_unlikely(child_node_flag_ptr) && ptr)
*child_node_flag_ptr = &pointers[i];
+ if (caa_unlikely(child_node_flag_v) && ptr)
+ *child_node_flag_v = ptr;
+ if (caa_unlikely(node_flag_ptr))
+ *node_flag_ptr = &pointers[i];
return ptr;
}
struct cds_ja_inode_flag *ja_pool_node_get_nth(const struct cds_ja_type *type,
struct cds_ja_inode *node,
struct cds_ja_inode_flag ***child_node_flag_ptr,
+ struct cds_ja_inode_flag **child_node_flag_v,
+ struct cds_ja_inode_flag ***node_flag_ptr,
uint8_t n)
{
struct cds_ja_inode *linear;
*/
linear = (struct cds_ja_inode *)
&node->u.data[((unsigned long) n >> (CHAR_BIT - type->nr_pool_order)) << type->pool_size_order];
- return ja_linear_node_get_nth(type, linear, child_node_flag_ptr, n);
+ return ja_linear_node_get_nth(type, linear, child_node_flag_ptr,
+ child_node_flag_v, node_flag_ptr, n);
}
static
struct cds_ja_inode_flag *ja_pigeon_node_get_nth(const struct cds_ja_type *type,
struct cds_ja_inode *node,
struct cds_ja_inode_flag ***child_node_flag_ptr,
+ struct cds_ja_inode_flag **child_node_flag_v,
+ struct cds_ja_inode_flag ***node_flag_ptr,
uint8_t n)
{
struct cds_ja_inode_flag **child_node_flag;
+ struct cds_ja_inode_flag *child_node_flag_read;
assert(type->type_class == RCU_JA_PIGEON);
child_node_flag = &((struct cds_ja_inode_flag **) node->u.data)[n];
+ child_node_flag_read = rcu_dereference(*child_node_flag);
dbg_printf("ja_pigeon_node_get_nth child_node_flag_ptr %p\n",
child_node_flag);
- if (caa_unlikely(child_node_flag_ptr) && *child_node_flag)
+ if (caa_unlikely(child_node_flag_ptr) && child_node_flag_read)
*child_node_flag_ptr = child_node_flag;
- return rcu_dereference(*child_node_flag);
+ if (caa_unlikely(child_node_flag_v) && child_node_flag_read)
+ *child_node_flag_v = child_node_flag_read;
+ if (caa_unlikely(node_flag_ptr))
+ *node_flag_ptr = child_node_flag;
+ return child_node_flag_read;
}
static
struct cds_ja_inode *node,
uint8_t i)
{
- return ja_pigeon_node_get_nth(type, node, NULL, i);
+ return ja_pigeon_node_get_nth(type, node, NULL, NULL, NULL, i);
}
/*
* node_flag is already rcu_dereference'd.
*/
static
-struct cds_ja_inode_flag * ja_node_get_nth(struct cds_ja_inode_flag *node_flag,
+struct cds_ja_inode_flag *ja_node_get_nth(struct cds_ja_inode_flag *node_flag,
struct cds_ja_inode_flag ***child_node_flag_ptr,
+ struct cds_ja_inode_flag **child_node_flag,
+ struct cds_ja_inode_flag ***node_flag_ptr,
uint8_t n)
{
unsigned int type_index;
switch (type->type_class) {
case RCU_JA_LINEAR:
return ja_linear_node_get_nth(type, node,
- child_node_flag_ptr, n);
+ child_node_flag_ptr, child_node_flag,
+ node_flag_ptr, n);
case RCU_JA_POOL:
return ja_pool_node_get_nth(type, node,
- child_node_flag_ptr, n);
+ child_node_flag_ptr, child_node_flag,
+ node_flag_ptr, n);
case RCU_JA_PIGEON:
return ja_pigeon_node_get_nth(type, node,
- child_node_flag_ptr, n);
+ child_node_flag_ptr, child_node_flag,
+ node_flag_ptr, n);
default:
assert(0);
return (void *) -1UL;
ret = _ja_node_set_nth(new_type, new_node,
new_shadow_node,
n, child_node_flag);
+ if (new_type->type_class == RCU_JA_POOL && ret) {
+ goto fallback_toosmall;
+ }
assert(!ret);
}
/* Return pointer to new recompacted node through old_node_flag_ptr */
uint8_t iter_key;
iter_key = (uint8_t) (key >> (JA_BITS_PER_BYTE * (tree_depth - i - 1)));
- node_flag = ja_node_get_nth(node_flag, NULL,
+ node_flag = ja_node_get_nth(node_flag, NULL, NULL, NULL,
iter_key);
dbg_printf("cds_ja_lookup iter key lookup %u finds node_flag %p\n",
(unsigned int) iter_key, node_flag);
*/
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 **node_flag_ptr,
struct cds_ja_inode_flag *node_flag,
struct cds_ja_inode_flag *parent_node_flag,
}
}
+ if (node_flag_ptr && ja_node_ptr(*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;
+ }
+
+ 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 */
CDS_INIT_HLIST_HEAD(&head);
cds_hlist_add_head_rcu(&child_node->list, &head);
/* Publish new branch */
dbg_printf("Publish branch %p, replacing %p\n",
- iter_node_flag, *node_flag_ptr);
- rcu_assign_pointer(*node_flag_ptr, iter_node_flag);
+ iter_node_flag, *attach_node_flag_ptr);
+ rcu_assign_pointer(*attach_node_flag_ptr, iter_node_flag);
/* Success */
ret = 0;
assert(!tmpret);
}
}
+unlock_parent:
if (parent_shadow_node)
rcuja_shadow_unlock(parent_shadow_node);
unlock_shadow:
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_hlist_head *head,
struct cds_ja_node *node)
{
struct cds_ja_shadow_node *shadow_node;
+ int ret = 0;
shadow_node = rcuja_shadow_lookup_lock(ja->ht, parent_node_flag);
- if (!shadow_node)
+ if (!shadow_node) {
return -EAGAIN;
+ }
+ if (ja_node_ptr(*node_flag_ptr) != ja_node_ptr(node_flag)) {
+ ret = -EAGAIN;
+ goto end;
+ }
cds_hlist_add_head_rcu(&node->list, head);
+end:
rcuja_shadow_unlock(shadow_node);
- return 0;
+ return ret;
}
int cds_ja_add(struct cds_ja *ja, uint64_t key,
struct cds_ja_node *new_node)
{
unsigned int tree_depth, i;
- struct cds_ja_inode_flag **node_flag_ptr; /* in parent */
+ struct cds_ja_inode_flag **attach_node_flag_ptr,
+ **node_flag_ptr;
struct cds_ja_inode_flag *node_flag,
*parent_node_flag,
- *parent2_node_flag;
+ *parent2_node_flag,
+ *attach_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:
parent2_node_flag = NULL;
parent_node_flag =
(struct cds_ja_inode_flag *) &ja->root; /* Use root ptr address as key for mutex */
+ attach_node_flag_ptr = &ja->root;
+ attach_node_flag = rcu_dereference(ja->root);
node_flag_ptr = &ja->root;
node_flag = rcu_dereference(ja->root);
for (i = 1; i < tree_depth; i++) {
uint8_t iter_key;
- dbg_printf("cds_ja_add iter node_flag_ptr %p node_flag %p\n",
- *node_flag_ptr, node_flag);
+ dbg_printf("cds_ja_add iter attach_node_flag_ptr %p node_flag_ptr %p node_flag %p\n",
+ attach_node_flag_ptr, node_flag_ptr, node_flag);
if (!ja_node_ptr(node_flag)) {
- ret = ja_attach_node(ja, node_flag_ptr,
- parent_node_flag, parent2_node_flag,
+ ret = ja_attach_node(ja, attach_node_flag_ptr,
+ attach_node_flag,
+ node_flag_ptr,
+ parent_node_flag,
+ parent2_node_flag,
key, i, new_node);
if (ret == -EAGAIN || ret == -EEXIST)
goto retry;
parent2_node_flag = parent_node_flag;
parent_node_flag = node_flag;
node_flag = ja_node_get_nth(node_flag,
+ &attach_node_flag_ptr,
+ &attach_node_flag,
&node_flag_ptr,
iter_key);
- dbg_printf("cds_ja_add iter key lookup %u finds node_flag %p node_flag_ptr %p\n",
- (unsigned int) iter_key, node_flag, *node_flag_ptr);
+ dbg_printf("cds_ja_add iter key lookup %u finds node_flag %p attach_node_flag_ptr %p node_flag_ptr %p\n",
+ (unsigned int) iter_key, node_flag,
+ attach_node_flag_ptr,
+ node_flag_ptr);
}
/*
* level, or chain it if key is already present.
*/
if (!ja_node_ptr(node_flag)) {
- dbg_printf("cds_ja_add last node_flag_ptr %p node_flag %p\n",
- *node_flag_ptr, node_flag);
- ret = ja_attach_node(ja, node_flag_ptr, parent_node_flag,
+ dbg_printf("cds_ja_add attach_node_flag_ptr %p node_flag_ptr %p node_flag %p\n",
+ attach_node_flag_ptr, node_flag_ptr, node_flag);
+ ret = ja_attach_node(ja, attach_node_flag_ptr,
+ attach_node_flag,
+ node_flag_ptr, parent_node_flag,
parent2_node_flag, key, i, new_node);
} else {
ret = ja_chain_node(ja,
parent_node_flag,
- (struct cds_hlist_head *) node_flag_ptr,
+ node_flag_ptr,
+ node_flag,
+ (struct cds_hlist_head *) attach_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,
ret = -EAGAIN;
goto end;
}
- assert(shadow_node->nr_child > 0);
shadow_nodes[nr_shadow++] = shadow_node;
- if (shadow_node->nr_child == 1)
+
+ /*
+ * 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) {
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
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 as to free lock here, because RCU read lock is
- * held, and free only performed in call_rcu.
+ * 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++) {
&iter_node_flag, /* Old new parent ptr in its 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);
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_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_hlist_node *hlist_node;
- int ret = 0, count = 0;
+ struct cds_hlist_head hlist_head;
+ 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;
+ }
+ hlist_head.next = (struct cds_hlist_node *) ja_node_ptr(node_flag);
/*
* Retry if another thread removed all but one of duplicates
- * since check (that was performed without lock).
+ * 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).
*/
- cds_hlist_for_each_rcu(hlist_node, head, list) {
+ cds_hlist_for_each_rcu(hlist_node, &hlist_head) {
+ if (count == 0) {
+ /* FIXME: currently a work-around */
+ hlist_node->prev = (struct cds_hlist_node *) node_flag_ptr;
+ }
count++;
+ if (hlist_node == &node->list)
+ found++;
}
-
- if (count == 1) {
+ assert(found <= 1);
+ if (!found || count == 1) {
ret = -EAGAIN;
goto end;
}
cds_hlist_del_rcu(&node->list);
+ /*
+ * Validate that we indeed removed the node from linked list.
+ */
+ assert(ja_node_ptr(*node_flag_ptr) != (struct cds_ja_inode *) node);
end:
rcuja_shadow_unlock(shadow_node);
return ret;
struct cds_ja_inode_flag **snapshot_ptr[JA_MAX_DEPTH];
uint8_t snapshot_n[JA_MAX_DEPTH];
struct cds_ja_inode_flag *node_flag;
- struct cds_ja_inode_flag **prev_node_flag_ptr;
+ struct cds_ja_inode_flag **prev_node_flag_ptr,
+ **node_flag_ptr;
int nr_snapshot;
int ret;
snapshot[nr_snapshot++] = (struct cds_ja_inode_flag *) &ja->root;
node_flag = rcu_dereference(ja->root);
prev_node_flag_ptr = &ja->root;
+ node_flag_ptr = &ja->root;
/* Iterate on all internal levels */
for (i = 1; i < tree_depth; i++) {
snapshot[nr_snapshot++] = node_flag;
node_flag = ja_node_get_nth(node_flag,
&prev_node_flag_ptr,
+ NULL,
+ &node_flag_ptr,
iter_key);
dbg_printf("cds_ja_del iter key lookup %u finds node_flag %p, prev_node_flag_ptr %p\n",
(unsigned int) iter_key, node_flag,
prev_node_flag_ptr);
}
-
/*
* We reached bottom of tree, try to find the node we are trying
* to remove. Fail if we cannot find it.
snapshot_n, nr_snapshot, key, node);
} else {
ret = ja_unchain_node(ja, snapshot[nr_snapshot - 1],
- &hlist_head, match);
+ node_flag_ptr, node_flag, 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 / userspace-rcu.git / blobdiff