* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
+#define _LGPL_SOURCE
#include <stdint.h>
#include <errno.h>
#include <limits.h>
/* 64-bit: 113 to 256 children, 2048 bytes */
/* Leaf nodes are implicit from their height in the tree */
RCU_JA_NR_TYPES,
+
+ RCU_JA_NULL, /* not an encoded type, but keeps code regular */
};
struct rcu_ja_type {
#define JA_ENTRY_PER_NODE 256UL
+/*
+ * Entry for NULL node is at index 8 of the table. It is never encoded
+ * in flags.
+ */
+#define NODE_INDEX_NULL 8
+
/*
* Iteration on the array to find the right node size for the number of
* children stops when it reaches .max_child == 256 (this is the largest
ja_type_5_max_child = 48,
ja_type_6_max_child = 92,
ja_type_7_max_child = 256,
+ ja_type_8_max_child = 0, /* NULL */
};
enum {
* filled beyond capacity, we need to roll back to pigeon.
*/
{ .type_class = RCU_JA_PIGEON, .min_child = 89, .max_child = ja_type_7_max_child, .order = 10, },
+
+ { .type_class = RCU_JA_NULL, .min_child = 0, .max_child = ja_type_8_max_child, },
};
#else /* !(CAA_BITS_PER_LONG < 64) */
/* 64-bit pointers */
ja_type_5_max_child = 54,
ja_type_6_max_child = 104,
ja_type_7_max_child = 256,
+ ja_type_8_max_child = 256,
};
enum {
* filled beyond capacity, we need to roll back to pigeon.
*/
{ .type_class = RCU_JA_PIGEON, .min_child = 101, .max_child = ja_type_7_max_child, .order = 11, },
+
+ { .type_class = RCU_JA_NULL, .min_child = 0, .max_child = ja_type_8_max_child, },
};
#endif /* !(BITS_PER_LONG < 64) */
static inline __attribute__((unused))
void static_array_size_check(void)
{
- CAA_BUILD_BUG_ON(CAA_ARRAY_SIZE(ja_types) > JA_TYPE_MAX_NR);
+ CAA_BUILD_BUG_ON(CAA_ARRAY_SIZE(ja_types) < JA_TYPE_MAX_NR);
}
-/* Never declared. Opaque type used to store flagged node pointers. */
-struct rcu_ja_node_flag;
-
/*
* The rcu_ja_node contains the compressed node data needed for
* read-side. For linear and pool node configurations, it starts with a
return (struct rcu_ja_node_flag *) (((unsigned long) node) | type);
}
+static
+struct rcu_ja_node *ja_node_ptr(struct rcu_ja_node_flag *node)
+{
+ return (struct rcu_ja_node *) (((unsigned long) node) | JA_PTR_MASK);
+}
+
static
unsigned int ja_node_type(struct rcu_ja_node_flag *node)
{
unsigned int type;
+ if (ja_node_ptr(node) == NULL) {
+ return NODE_INDEX_NULL;
+ }
type = (unsigned int) ((unsigned long) node & JA_TYPE_MASK);
assert(type < RCU_JA_NR_TYPES);
return type;
}
-static
-struct rcu_ja_node *ja_node_ptr(struct rcu_ja_node_flag *node)
-{
- return (struct rcu_ja_node *) (((unsigned long) node) | JA_PTR_MASK);
-}
-
-struct rcu_ja_node *alloc_rcu_ja_node(struct rcu_ja_type *ja_type)
+struct rcu_ja_node *alloc_rcu_ja_node(const struct rcu_ja_type *ja_type)
{
return calloc(1U << ja_type->order, sizeof(char));
}
struct rcu_ja_node *linear;
assert(type->type_class == RCU_JA_POOL);
+ /*
+ * TODO: currently, we select the pool by highest bits. We
+ * should support various encodings.
+ */
linear = (struct rcu_ja_node *)
&node->u.data[((unsigned long) n >> (CHAR_BIT - type->nr_pool_order)) << type->pool_size_order];
return ja_linear_node_get_nth(type, linear, n);
}
}
+static
+unsigned int ja_get_nr_child(struct rcu_ja_shadow_node *shadow_node)
+{
+ return shadow_node->nr_child;
+}
+
static
int ja_linear_node_set_nth(const struct rcu_ja_type *type,
struct rcu_ja_node *node,
+ struct rcu_ja_shadow_node *shadow_node,
uint8_t n,
struct rcu_ja_node_flag *child_node_flag)
{
CMM_STORE_SHARED(values[nr_child], n);
cmm_smp_wmb(); /* write value and pointer before nr_child */
CMM_STORE_SHARED(*nr_child_ptr, nr_child + 1);
+ shadow_node->nr_child++;
return 0;
}
static
int ja_pool_node_set_nth(const struct rcu_ja_type *type,
struct rcu_ja_node *node,
+ struct rcu_ja_shadow_node *shadow_node,
uint8_t n,
struct rcu_ja_node_flag *child_node_flag)
{
assert(type->type_class == RCU_JA_POOL);
linear = (struct rcu_ja_node *)
&node->u.data[((unsigned long) n >> (CHAR_BIT - type->nr_pool_order)) << type->pool_size_order];
- return ja_linear_node_set_nth(type, linear, n, child_node_flag);
+ return ja_linear_node_set_nth(type, linear, shadow_node,
+ n, child_node_flag);
}
static
int ja_pigeon_node_set_nth(const struct rcu_ja_type *type,
struct rcu_ja_node *node,
+ struct rcu_ja_shadow_node *shadow_node,
uint8_t n,
struct rcu_ja_node_flag *child_node_flag)
{
if (*ptr != NULL)
return -EEXIST;
rcu_assign_pointer(*ptr, child_node_flag);
+ shadow_node->nr_child++;
return 0;
}
/*
- * ja_node_set_nth: set nth item within a node. Return an error
+ * _ja_node_set_nth: set nth item within a node. Return an error
* (negative error value) if it is already there.
* TODO: exclusive access on node.
*/
static
-int ja_node_set_nth(struct rcu_ja_node_flag *node_flag, uint8_t n,
+int _ja_node_set_nth(const struct rcu_ja_type *type,
+ struct rcu_ja_node *node,
+ struct rcu_ja_shadow_node *shadow_node,
+ uint8_t n,
struct rcu_ja_node_flag *child_node_flag)
{
- unsigned int type_index;
- struct rcu_ja_node *node;
- const struct rcu_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_set_nth(type, node, n,
+ return ja_linear_node_set_nth(type, node, shadow_node, n,
child_node_flag);
case RCU_JA_POOL:
- return ja_pool_node_set_nth(type, node, n,
+ return ja_pool_node_set_nth(type, node, shadow_node, n,
child_node_flag);
case RCU_JA_PIGEON:
- return ja_pigeon_node_set_nth(type, node, n,
+ return ja_pigeon_node_set_nth(type, node, shadow_node, n,
child_node_flag);
+ case RCU_JA_NULL:
+ return -ENOSPC;
default:
assert(0);
return -EINVAL;
return 0;
}
+
+/*
+ * ja_node_recompact_add: recompact a node, adding a new child.
+ * TODO: for pool type, take selection bit(s) into account.
+ */
+static
+int ja_node_recompact_add(struct rcu_ja *ja,
+ unsigned int old_type_index,
+ const struct rcu_ja_type *old_type,
+ struct rcu_ja_node *old_node,
+ struct rcu_ja_shadow_node **shadow_node,
+ struct rcu_ja_node_flag **old_node_flag, uint8_t n,
+ struct rcu_ja_node_flag *child_node_flag)
+{
+ unsigned int new_type_index;
+ struct rcu_ja_node *new_node;
+ const struct rcu_ja_type *new_type;
+ struct rcu_ja_node_flag *new_node_flag;
+ unsigned int i;
+ int ret;
+
+ if (*shadow_node == NULL) {
+ new_type_index = 0;
+ } else {
+ new_type_index = old_type_index + 1;
+ }
+ new_type = &ja_types[new_type_index];
+ new_node = alloc_rcu_ja_node(new_type);
+ if (!new_node)
+ return -ENOMEM;
+ new_node_flag = ja_node_flag(new_node, new_type_index);
+
+ ret = rcuja_shadow_set(ja->ht, new_node, *shadow_node);
+ if (ret)
+ return ret;
+
+ if (*shadow_node == NULL) {
+ *shadow_node = rcuja_shadow_lookup_lock(ja->ht, new_node);
+ assert(*shadow_node);
+ }
+
+ (*shadow_node)->nr_child = 0;
+ for (i = 0; i < old_type->max_child; i++) {
+ struct rcu_ja_node_flag *iter;
+
+ iter = ja_node_get_nth(*old_node_flag, i);
+ if (!iter)
+ continue;
+ ret = _ja_node_set_nth(new_type, new_node, *shadow_node,
+ i, iter);
+ assert(!ret);
+ }
+ /* add node */
+ ret = _ja_node_set_nth(new_type, new_node, *shadow_node,
+ n, child_node_flag);
+ assert(!ret);
+ /* Replace the old node with the new recompacted one */
+ rcu_assign_pointer(*old_node_flag, new_node_flag);
+ ret = rcuja_shadow_clear(ja->ht, old_node,
+ RCUJA_SHADOW_CLEAR_FREE_NODE);
+ assert(!ret);
+ return 0;
+}
+
+static
+int ja_node_set_nth(struct rcu_ja *ja,
+ struct rcu_ja_node_flag **node_flag, uint8_t n,
+ struct rcu_ja_node_flag *child_node_flag)
+{
+ int ret;
+ unsigned int type_index;
+ const struct rcu_ja_type *type;
+ struct rcu_ja_node *node;
+ struct rcu_ja_shadow_node *shadow_node = NULL;
+
+ node = ja_node_ptr(*node_flag);
+ type_index = ja_node_type(*node_flag);
+ type = &ja_types[type_index];
+ if (node != NULL) {
+ shadow_node = rcuja_shadow_lookup_lock(ja->ht, node);
+ assert(shadow_node);
+ }
+ ret = _ja_node_set_nth(type, node, shadow_node,
+ n, child_node_flag);
+ if (ret == -ENOSPC) {
+ /* Not enough space in node, need to recompact. */
+ ret = ja_node_recompact_add(ja, type_index, type, node,
+ &shadow_node, node_flag, n, child_node_flag);
+ /* recompact always leave shadow_node locked */
+ }
+ rcuja_shadow_unlock(shadow_node);
+ return ret;
+}