* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
+#define _LGPL_SOURCE
#include <stdint.h>
#include <errno.h>
#include <limits.h>
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 *) (((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));
}
return (uint8_t *) JA_ALIGN((unsigned long) ptr, sizeof(void *));
}
+/*
+ * The order in which values and pointers are does does not matter: if
+ * a value is missing, we return NULL. If a value is there, but its
+ * associated pointers is still NULL, we return NULL too.
+ */
static
struct rcu_ja_node_flag *ja_linear_node_get_nth(const struct rcu_ja_type *type,
struct rcu_ja_node *node,
assert(type->type_class == RCU_JA_LINEAR || type->type_class == RCU_JA_POOL);
- nr_child = node->u.data[0];
- cmm_smp_rmb(); /* read nr_child before values */
+ nr_child = CMM_LOAD_SHARED(node->u.data[0]);
+ 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++) {
- if (values[i] == n)
+ if (CMM_LOAD_SHARED(values[i]) == n)
break;
}
if (i >= nr_child)
return NULL;
- cmm_smp_rmb(); /* read values before pointer */
pointers = (struct rcu_ja_node_flag **) align_ptr_size(&values[type->max_linear_child]);
- ptr = pointers[i];
+ ptr = rcu_dereference(pointers[i]);
assert(ja_node_ptr(ptr) != NULL);
return ptr;
}
uint8_t n)
{
assert(type->type_class == RCU_JA_PIGEON);
- return ((struct rcu_ja_node_flag **) node->u.data)[n];
+ return rcu_dereference(((struct rcu_ja_node_flag **) node->u.data)[n]);
}
-/* ja_node_get_nth: get nth item from a node */
+/*
+ * ja_node_get_nth: get nth item from a node.
+ * node_flag is already rcu_dereference'd.
+ */
static
struct rcu_ja_node_flag *ja_node_get_nth(struct rcu_ja_node_flag *node_flag,
uint8_t n)
struct rcu_ja_node *node;
const struct rcu_ja_type *type;
- node_flag = rcu_dereference(node_flag);
node = ja_node_ptr(node_flag);
assert(node != NULL);
type_index = ja_node_type(node_flag);
return -ENOSPC;
}
pointers = (struct rcu_ja_node_flag **) align_ptr_size(&values[type->max_linear_child]);
- pointers[nr_child] = child_node_flag;
- (*nr_child_ptr)++;
+ assert(pointers[nr_child] == NULL);
+ rcu_assign_pointer(pointers[nr_child], 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);
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(struct rcu_ja_node_flag *node_flag, uint8_t n,
struct rcu_ja_node_flag *child_node_flag)
{
unsigned int type_index;
return 0;
}
+
+/*
+ * ja_node_recompact_add: recompact a node, adding a new child.
+ */
+static
+int ja_node_recompact_add(struct rcu_ja_node_flag **old_node_flag, uint8_t n,
+ struct rcu_ja_node_flag *child_node_flag)
+
+{
+ unsigned int old_type_index, new_type_index;
+ struct rcu_ja_node *old_node, *new_node;
+ const struct rcu_ja_type *old_type, *new_type;
+ struct rcu_ja_node_flag *new_node_flag;
+ unsigned int i;
+ int ret;
+
+ old_node = ja_node_ptr(*old_node_flag);
+ if (old_node == NULL) {
+ new_type_index = 0;
+ } else {
+ old_type_index = ja_node_type(*old_node_flag);
+ old_type = &ja_types[old_type_index];
+ 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);
+
+ 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_node_flag, i, iter);
+ assert(!ret);
+ }
+ /* add node */
+ ret = _ja_node_set_nth(new_node_flag, n, child_node_flag);
+ assert(!ret);
+ /* Replace the old node with the new recompacted one */
+ rcu_assign_pointer(*old_node_flag, new_node_flag);
+ /* TODO: free old_node (call_rcu) */
+ return 0;
+}
+
+static
+int ja_node_set_nth(struct rcu_ja_node_flag **node_flag, uint8_t n,
+ struct rcu_ja_node_flag *child_node_flag)
+{
+ int ret;
+
+ ret = _ja_node_set_nth(*node_flag, n, child_node_flag);
+ if (ret == -ENOSPC) {
+ /* Not enough space in node, need to recompact */
+ ret = ja_node_recompact_add(node_flag, n,
+ child_node_flag);
+ if (ret < 0)
+ return ret;
+ }
+ return ret;
+}
projects / userspace-rcu.git / blobdiff