* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
+#define _LGPL_SOURCE
+#include <stdint.h>
+#include <errno.h>
+#include <limits.h>
#include <urcu/rcuja.h>
+#include <urcu/compiler.h>
+#include <urcu/arch.h>
+#include <assert.h>
+#include <urcu-pointer.h>
+
#include "rcuja-internal.h"
+#include "bitfield.h"
+
+enum rcu_ja_type_class {
+ RCU_JA_LINEAR = 0, /* Type A */
+ /* 32-bit: 1 to 25 children, 8 to 128 bytes */
+ /* 64-bit: 1 to 28 children, 16 to 256 bytes */
+ RCU_JA_POOL = 1, /* Type B */
+ /* 32-bit: 26 to 100 children, 256 to 512 bytes */
+ /* 64-bit: 29 to 112 children, 512 to 1024 bytes */
+ RCU_JA_PIGEON = 2, /* Type C */
+ /* 32-bit: 101 to 256 children, 1024 bytes */
+ /* 64-bit: 113 to 256 children, 2048 bytes */
+ /* Leaf nodes are implicit from their height in the tree */
+ RCU_JA_NR_TYPES,
+};
+
+struct rcu_ja_type {
+ enum rcu_ja_type_class type_class;
+ uint16_t min_child; /* minimum number of children: 1 to 256 */
+ uint16_t max_child; /* maximum number of children: 1 to 256 */
+ uint16_t max_linear_child; /* per-pool max nr. children: 1 to 256 */
+ uint16_t order; /* node size is (1 << order), in bytes */
+ uint16_t nr_pool_order; /* number of pools */
+ uint16_t pool_size_order; /* pool size */
+};
+
+/*
+ * Number of least significant pointer bits reserved to represent the
+ * child type.
+ */
+#define JA_TYPE_BITS 3
+#define JA_TYPE_MAX_NR (1U << JA_TYPE_BITS)
+#define JA_TYPE_MASK (JA_TYPE_MAX_NR - 1)
+#define JA_PTR_MASK (~JA_TYPE_MASK)
+
+#define JA_ENTRY_PER_NODE 256UL
+
+/*
+ * 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
+ * possible node size, which contains 256 children).
+ * The min_child overlaps with the previous max_child to provide an
+ * hysteresis loop to reallocation for patterns of cyclic add/removal
+ * within the same node.
+ * The node the index within the following arrays is represented on 3
+ * bits. It identifies the node type, min/max number of children, and
+ * the size order.
+ * The max_child values for the RCU_JA_POOL below result from
+ * statistical approximation: over million populations, the max_child
+ * covers between 97% and 99% of the populations generated. Therefore, a
+ * fallback should exist to cover the rare extreme population unbalance
+ * cases, but it will not have a major impact on speed nor space
+ * consumption, since those are rare cases.
+ */
+
+#if (CAA_BITS_PER_LONG < 64)
+/* 32-bit pointers */
+enum {
+ ja_type_0_max_child = 1,
+ ja_type_1_max_child = 3,
+ ja_type_2_max_child = 6,
+ ja_type_3_max_child = 12,
+ ja_type_4_max_child = 25,
+ ja_type_5_max_child = 48,
+ ja_type_6_max_child = 92,
+ ja_type_7_max_child = 256,
+};
+
+enum {
+ ja_type_0_max_linear_child = 1,
+ ja_type_1_max_linear_child = 3,
+ ja_type_2_max_linear_child = 6,
+ ja_type_3_max_linear_child = 12,
+ ja_type_4_max_linear_child = 25,
+ ja_type_5_max_linear_child = 24,
+ ja_type_6_max_linear_child = 23,
+};
+
+enum {
+ ja_type_5_nr_pool_order = 1,
+ ja_type_6_nr_pool_order = 2,
+};
+
+const struct rcu_ja_type ja_types[] = {
+ { .type_class = RCU_JA_LINEAR, .min_child = 1, .max_child = ja_type_0_max_child, .max_linear_child = ja_type_0_max_linear_child, .order = 3, },
+ { .type_class = RCU_JA_LINEAR, .min_child = 1, .max_child = ja_type_1_max_child, .max_linear_child = ja_type_1_max_linear_child, .order = 4, },
+ { .type_class = RCU_JA_LINEAR, .min_child = 3, .max_child = ja_type_2_max_child, .max_linear_child = ja_type_2_max_linear_child, .order = 5, },
+ { .type_class = RCU_JA_LINEAR, .min_child = 4, .max_child = ja_type_3_max_child, .max_linear_child = ja_type_3_max_linear_child, .order = 6, },
+ { .type_class = RCU_JA_LINEAR, .min_child = 10, .max_child = ja_type_4_max_child, .max_linear_child = ja_type_4_max_linear_child, .order = 7, },
+
+ /* Pools may fill sooner than max_child */
+ { .type_class = RCU_JA_POOL, .min_child = 20, .max_child = ja_type_5_max_child, .max_linear_child = ja_type_5_max_linear_child, .order = 8, .nr_pool_order = ja_type_5_nr_pool_order, .pool_size_order = 7, },
+ { .type_class = RCU_JA_POOL, .min_child = 45, .max_child = ja_type_6_max_child, .max_linear_child = ja_type_6_max_linear_child, .order = 9, .nr_pool_order = ja_type_6_nr_pool_order, .pool_size_order = 7, },
+
+ /*
+ * TODO: Upon node removal below min_child, if child pool is
+ * 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, },
+};
+#else /* !(CAA_BITS_PER_LONG < 64) */
+/* 64-bit pointers */
+enum {
+ ja_type_0_max_child = 1,
+ ja_type_1_max_child = 3,
+ ja_type_2_max_child = 7,
+ ja_type_3_max_child = 14,
+ ja_type_4_max_child = 28,
+ ja_type_5_max_child = 54,
+ ja_type_6_max_child = 104,
+ ja_type_7_max_child = 256,
+};
+
+enum {
+ ja_type_0_max_linear_child = 1,
+ ja_type_1_max_linear_child = 3,
+ ja_type_2_max_linear_child = 7,
+ ja_type_3_max_linear_child = 14,
+ ja_type_4_max_linear_child = 28,
+ ja_type_5_max_linear_child = 27,
+ ja_type_6_max_linear_child = 26,
+};
+
+enum {
+ ja_type_5_nr_pool_order = 1,
+ ja_type_6_nr_pool_order = 2,
+};
+
+const struct rcu_ja_type ja_types[] = {
+ { .type_class = RCU_JA_LINEAR, .min_child = 1, .max_child = ja_type_0_max_child, .max_linear_child = ja_type_0_max_linear_child, .order = 4, },
+ { .type_class = RCU_JA_LINEAR, .min_child = 1, .max_child = ja_type_1_max_child, .max_linear_child = ja_type_1_max_linear_child, .order = 5, },
+ { .type_class = RCU_JA_LINEAR, .min_child = 3, .max_child = ja_type_2_max_child, .max_linear_child = ja_type_2_max_linear_child, .order = 6, },
+ { .type_class = RCU_JA_LINEAR, .min_child = 5, .max_child = ja_type_3_max_child, .max_linear_child = ja_type_3_max_linear_child, .order = 7, },
+ { .type_class = RCU_JA_LINEAR, .min_child = 10, .max_child = ja_type_4_max_child, .max_linear_child = ja_type_4_max_linear_child, .order = 8, },
+
+ /* Pools may fill sooner than max_child. */
+ { .type_class = RCU_JA_POOL, .min_child = 22, .max_child = ja_type_5_max_child, .max_linear_child = ja_type_5_max_linear_child, .order = 9, .nr_pool_order = ja_type_5_nr_pool_order, .pool_size_order = 8, },
+ { .type_class = RCU_JA_POOL, .min_child = 51, .max_child = ja_type_6_max_child, .max_linear_child = ja_type_6_max_linear_child, .order = 10, .nr_pool_order = ja_type_6_nr_pool_order, .pool_size_order = 8, },
+
+ /*
+ * TODO: Upon node removal below min_child, if child pool is
+ * 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, },
+};
+#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);
+}
+
+/*
+ * The rcu_ja_node contains the compressed node data needed for
+ * read-side. For linear and pool node configurations, it starts with a
+ * byte counting the number of children in the node. Then, the
+ * node-specific data is placed.
+ * The node mutex, if any is needed, protecting concurrent updated of
+ * each node is placed in a separate hash table indexed by node address.
+ * For the pigeon configuration, the number of children is also kept in
+ * a separate hash table, indexed by node address, because it is only
+ * required for updates.
+ */
+
+#define DECLARE_LINEAR_NODE(index) \
+ struct { \
+ uint8_t nr_child; \
+ uint8_t child_value[ja_type_## index ##_max_linear_child]; \
+ struct rcu_ja_node_flag *child_ptr[ja_type_## index ##_max_linear_child]; \
+ }
+
+#define DECLARE_POOL_NODE(index) \
+ struct { \
+ struct { \
+ uint8_t nr_child; \
+ uint8_t child_value[ja_type_## index ##_max_linear_child]; \
+ struct rcu_ja_node_flag *child_ptr[ja_type_## index ##_max_linear_child]; \
+ } linear[1U << ja_type_## index ##_nr_pool_order]; \
+ }
+
+struct rcu_ja_node {
+ union {
+ /* Linear configuration */
+ DECLARE_LINEAR_NODE(0) conf_0;
+ DECLARE_LINEAR_NODE(1) conf_1;
+ DECLARE_LINEAR_NODE(2) conf_2;
+ DECLARE_LINEAR_NODE(3) conf_3;
+ DECLARE_LINEAR_NODE(4) conf_4;
+
+ /* Pool configuration */
+ DECLARE_POOL_NODE(5) conf_5;
+ DECLARE_POOL_NODE(6) conf_6;
+
+ /* Pigeon configuration */
+ struct {
+ struct rcu_ja_node_flag *child[ja_type_7_max_child];
+ } conf_7;
+ /* data aliasing nodes for computed accesses */
+ uint8_t data[sizeof(struct rcu_ja_node_flag *) * ja_type_7_max_child];
+ } u;
+};
+
+static
+struct rcu_ja_node_flag *ja_node_flag(struct rcu_ja_node *node,
+ unsigned int type)
+{
+ assert(type < RCU_JA_NR_TYPES);
+ return (struct rcu_ja_node_flag *) (((unsigned long) node) | type);
+}
+
+static
+unsigned int ja_node_type(struct rcu_ja_node_flag *node)
+{
+ unsigned int type;
+
+ 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(const struct rcu_ja_type *ja_type)
+{
+ return calloc(1U << ja_type->order, sizeof(char));
+}
+
+void free_rcu_ja_node(struct rcu_ja_node *node)
+{
+ free(node);
+}
+
+#define __JA_ALIGN_MASK(v, mask) (((v) + (mask)) & ~(mask))
+#define JA_ALIGN(v, align) __JA_ALIGN_MASK(v, (typeof(v)) (align) - 1)
+#define __JA_FLOOR_MASK(v, mask) ((v) & ~(mask))
+#define JA_FLOOR(v, align) __JA_FLOOR_MASK(v, (typeof(v)) (align) - 1)
+
+static
+uint8_t *align_ptr_size(uint8_t *ptr)
+{
+ 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,
+ uint8_t n)
+{
+ uint8_t nr_child;
+ uint8_t *values;
+ struct rcu_ja_node_flag **pointers;
+ struct rcu_ja_node_flag *ptr;
+ unsigned int i;
+
+ assert(type->type_class == RCU_JA_LINEAR || type->type_class == RCU_JA_POOL);
+
+ 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 (CMM_LOAD_SHARED(values[i]) == n)
+ break;
+ }
+ if (i >= nr_child)
+ return NULL;
+ pointers = (struct rcu_ja_node_flag **) align_ptr_size(&values[type->max_linear_child]);
+ ptr = rcu_dereference(pointers[i]);
+ assert(ja_node_ptr(ptr) != NULL);
+ return ptr;
+}
+
+static
+struct rcu_ja_node_flag *ja_pool_node_get_nth(const struct rcu_ja_type *type,
+ struct rcu_ja_node *node,
+ uint8_t n)
+{
+ struct rcu_ja_node *linear;
+
+ 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_get_nth(type, linear, n);
+}
+
+static
+struct rcu_ja_node_flag *ja_pigeon_node_get_nth(const struct rcu_ja_type *type,
+ struct rcu_ja_node *node,
+ uint8_t n)
+{
+ assert(type->type_class == RCU_JA_PIGEON);
+ return rcu_dereference(((struct rcu_ja_node_flag **) node->u.data)[n]);
+}
+
+/*
+ * 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)
+{
+ 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_get_nth(type, node, n);
+ case RCU_JA_POOL:
+ return ja_pool_node_get_nth(type, node, n);
+ case RCU_JA_PIGEON:
+ return ja_pigeon_node_get_nth(type, node, n);
+ default:
+ assert(0);
+ return (void *) -1UL;
+ }
+}
+
+static
+int ja_linear_node_set_nth(const struct rcu_ja_type *type,
+ struct rcu_ja_node *node,
+ uint8_t n,
+ struct rcu_ja_node_flag *child_node_flag)
+{
+ uint8_t nr_child;
+ uint8_t *values, *nr_child_ptr;
+ struct rcu_ja_node_flag **pointers;
+ unsigned int i;
+
+ assert(type->type_class == RCU_JA_LINEAR || type->type_class == RCU_JA_POOL);
+
+ nr_child_ptr = &node->u.data[0];
+ nr_child = *nr_child_ptr;
+ 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)
+ return -EEXIST;
+ }
+ if (nr_child >= type->max_linear_child) {
+ /* No space left in this node type */
+ return -ENOSPC;
+ }
+ pointers = (struct rcu_ja_node_flag **) align_ptr_size(&values[type->max_linear_child]);
+ 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;
+}
+
+static
+int ja_pool_node_set_nth(const struct rcu_ja_type *type,
+ struct rcu_ja_node *node,
+ uint8_t n,
+ struct rcu_ja_node_flag *child_node_flag)
+{
+ struct rcu_ja_node *linear;
+
+ 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);
+}
+
+static
+int ja_pigeon_node_set_nth(const struct rcu_ja_type *type,
+ struct rcu_ja_node *node,
+ uint8_t n,
+ struct rcu_ja_node_flag *child_node_flag)
+{
+ struct rcu_ja_node_flag **ptr;
+
+ assert(type->type_class == RCU_JA_PIGEON);
+ ptr = &((struct rcu_ja_node_flag **) node->u.data)[n];
+ if (*ptr != NULL)
+ return -EEXIST;
+ rcu_assign_pointer(*ptr, child_node_flag);
+ return 0;
+}
+
+/*
+ * _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,
+ 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,
+ child_node_flag);
+ case RCU_JA_POOL:
+ return ja_pool_node_set_nth(type, node, n,
+ child_node_flag);
+ case RCU_JA_PIGEON:
+ return ja_pigeon_node_set_nth(type, node, n,
+ child_node_flag);
+ default:
+ assert(0);
+ return -EINVAL;
+ }
+
+ 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