[userspace-rcu.git] / rcuja / rcuja.c

/*
 * rcuja/rcuja.c
 *
 * Userspace RCU library - RCU Judy Array
 *
 * Copyright 2012 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#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);
}

/* 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
 * 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(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 *));
}

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 = node->u.data[0];
	cmm_smp_rmb();	/* read nr_child before values */
	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)
			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];
	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 ((struct rcu_ja_node_flag **) node->u.data)[n];
}

/* ja_node_get_nth: get nth item from a node */
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_flag = rcu_dereference(node_flag);
	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]);
	pointers[nr_child] = child_node_flag;
	(*nr_child_ptr)++;
	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;
}
Commit	Line	Data
61009379 MD	1	/*
	2	* rcuja/rcuja.c
	3	*
	4	* Userspace RCU library - RCU Judy Array
	5	*
	6	* Copyright 2012 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
	7	*
	8	* This library is free software; you can redistribute it and/or
	9	* modify it under the terms of the GNU Lesser General Public
	10	* License as published by the Free Software Foundation; either
	11	* version 2.1 of the License, or (at your option) any later version.
	12	*
	13	* This library is distributed in the hope that it will be useful,
	14	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	15	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	16	* Lesser General Public License for more details.
	17	*
	18	* You should have received a copy of the GNU Lesser General Public
	19	* License along with this library; if not, write to the Free Software
	20	* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
	21	*/
	22
e5227865	23	#include <stdint.h>
8e519e3c	24	#include <errno.h>
d68c6810	25	#include <limits.h>
61009379	26	#include <urcu/rcuja.h>
d68c6810 MD	27	#include <urcu/compiler.h>
	28	#include <urcu/arch.h>
	29	#include <assert.h>
8e519e3c MD	30	#include <urcu-pointer.h>
8e519e3c MD	31
61009379	32	#include "rcuja-internal.h"
d68c6810	33	#include "bitfield.h"
61009379	34
d68c6810	35	enum rcu_ja_type_class {
e5227865	36	RCU_JA_LINEAR = 0, /* Type A */
fd800776 MD	37	/* 32-bit: 1 to 25 children, 8 to 128 bytes */
	38	/* 64-bit: 1 to 28 children, 16 to 256 bytes */
	39	RCU_JA_POOL = 1, /* Type B */
	40	/* 32-bit: 26 to 100 children, 256 to 512 bytes */
	41	/* 64-bit: 29 to 112 children, 512 to 1024 bytes */
e5227865	42	RCU_JA_PIGEON = 2, /* Type C */
fd800776 MD	43	/* 32-bit: 101 to 256 children, 1024 bytes */
fd800776 MD	44	/* 64-bit: 113 to 256 children, 2048 bytes */
e5227865	45	/* Leaf nodes are implicit from their height in the tree */
1db4943c	46	RCU_JA_NR_TYPES,
e5227865 MD	47	};
e5227865 MD	48
d68c6810 MD	49	struct rcu_ja_type {
d68c6810 MD	50	enum rcu_ja_type_class type_class;
8e519e3c MD	51	uint16_t min_child; /* minimum number of children: 1 to 256 */
	52	uint16_t max_child; /* maximum number of children: 1 to 256 */
	53	uint16_t max_linear_child; /* per-pool max nr. children: 1 to 256 */
	54	uint16_t order; /* node size is (1 << order), in bytes */
fd800776 MD	55	uint16_t nr_pool_order; /* number of pools */
fd800776 MD	56	uint16_t pool_size_order; /* pool size */
e5227865 MD	57	};
e5227865 MD	58
d68c6810 MD	59	/*
	60	* Number of least significant pointer bits reserved to represent the
	61	* child type.
	62	*/
	63	#define JA_TYPE_BITS 3
	64	#define JA_TYPE_MAX_NR (1U << JA_TYPE_BITS)
	65	#define JA_TYPE_MASK (JA_TYPE_MAX_NR - 1)
	66	#define JA_PTR_MASK (~JA_TYPE_MASK)
	67
	68	#define JA_ENTRY_PER_NODE 256UL
	69
e5227865 MD	70	/*
e5227865 MD	71	* Iteration on the array to find the right node size for the number of
d68c6810	72	* children stops when it reaches .max_child == 256 (this is the largest
e5227865	73	* possible node size, which contains 256 children).
d68c6810 MD	74	* The min_child overlaps with the previous max_child to provide an
	75	* hysteresis loop to reallocation for patterns of cyclic add/removal
	76	* within the same node.
	77	* The node the index within the following arrays is represented on 3
	78	* bits. It identifies the node type, min/max number of children, and
	79	* the size order.
3d45251f MD	80	* The max_child values for the RCU_JA_POOL below result from
	81	* statistical approximation: over million populations, the max_child
	82	* covers between 97% and 99% of the populations generated. Therefore, a
	83	* fallback should exist to cover the rare extreme population unbalance
	84	* cases, but it will not have a major impact on speed nor space
	85	* consumption, since those are rare cases.
e5227865	86	*/
e5227865	87
d68c6810 MD	88	#if (CAA_BITS_PER_LONG < 64)
d68c6810 MD	89	/* 32-bit pointers */
1db4943c MD	90	enum {
	91	ja_type_0_max_child = 1,
	92	ja_type_1_max_child = 3,
	93	ja_type_2_max_child = 6,
	94	ja_type_3_max_child = 12,
	95	ja_type_4_max_child = 25,
	96	ja_type_5_max_child = 48,
	97	ja_type_6_max_child = 92,
	98	ja_type_7_max_child = 256,
	99	};
	100
8e519e3c MD	101	enum {
	102	ja_type_0_max_linear_child = 1,
	103	ja_type_1_max_linear_child = 3,
	104	ja_type_2_max_linear_child = 6,
	105	ja_type_3_max_linear_child = 12,
	106	ja_type_4_max_linear_child = 25,
	107	ja_type_5_max_linear_child = 24,
	108	ja_type_6_max_linear_child = 23,
	109	};
	110
1db4943c MD	111	enum {
	112	ja_type_5_nr_pool_order = 1,
	113	ja_type_6_nr_pool_order = 2,
	114	};
	115
d68c6810	116	const struct rcu_ja_type ja_types[] = {
8e519e3c MD	117	{ .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, },
	118	{ .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, },
	119	{ .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, },
	120	{ .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, },
	121	{ .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, },
e5227865	122
fd800776	123	/* Pools may fill sooner than max_child */
8e519e3c MD	124	{ .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, },
8e519e3c MD	125	{ .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, },
3d45251f MD	126
	127	/*
	128	* TODO: Upon node removal below min_child, if child pool is
	129	* filled beyond capacity, we need to roll back to pigeon.
	130	*/
1db4943c	131	{ .type_class = RCU_JA_PIGEON, .min_child = 89, .max_child = ja_type_7_max_child, .order = 10, },
d68c6810	132	};
d68c6810 MD	133	#else /* !(CAA_BITS_PER_LONG < 64) */
d68c6810 MD	134	/* 64-bit pointers */
1db4943c MD	135	enum {
	136	ja_type_0_max_child = 1,
	137	ja_type_1_max_child = 3,
	138	ja_type_2_max_child = 7,
	139	ja_type_3_max_child = 14,
	140	ja_type_4_max_child = 28,
	141	ja_type_5_max_child = 54,
	142	ja_type_6_max_child = 104,
	143	ja_type_7_max_child = 256,
	144	};
	145
8e519e3c MD	146	enum {
	147	ja_type_0_max_linear_child = 1,
	148	ja_type_1_max_linear_child = 3,
	149	ja_type_2_max_linear_child = 7,
	150	ja_type_3_max_linear_child = 14,
	151	ja_type_4_max_linear_child = 28,
	152	ja_type_5_max_linear_child = 27,
	153	ja_type_6_max_linear_child = 26,
	154	};
	155
1db4943c MD	156	enum {
	157	ja_type_5_nr_pool_order = 1,
	158	ja_type_6_nr_pool_order = 2,
	159	};
	160
d68c6810	161	const struct rcu_ja_type ja_types[] = {
8e519e3c MD	162	{ .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, },
	163	{ .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, },
	164	{ .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, },
	165	{ .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, },
	166	{ .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, },
e5227865	167
3d45251f	168	/* Pools may fill sooner than max_child. */
8e519e3c MD	169	{ .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, },
8e519e3c MD	170	{ .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, },
e5227865	171
3d45251f MD	172	/*
	173	* TODO: Upon node removal below min_child, if child pool is
	174	* filled beyond capacity, we need to roll back to pigeon.
	175	*/
1db4943c	176	{ .type_class = RCU_JA_PIGEON, .min_child = 101, .max_child = ja_type_7_max_child, .order = 11, },
e5227865	177	};
d68c6810	178	#endif /* !(BITS_PER_LONG < 64) */
e5227865	179
1db4943c MD	180	static inline __attribute__((unused))
	181	void static_array_size_check(void)
	182	{
	183	CAA_BUILD_BUG_ON(CAA_ARRAY_SIZE(ja_types) > JA_TYPE_MAX_NR);
	184	}
	185
	186	/* Never declared. Opaque type used to store flagged node pointers. */
	187	struct rcu_ja_node_flag;
	188
e5227865	189	/*
1db4943c MD	190	* The rcu_ja_node contains the compressed node data needed for
	191	* read-side. For linear and pool node configurations, it starts with a
	192	* byte counting the number of children in the node. Then, the
	193	* node-specific data is placed.
	194	* The node mutex, if any is needed, protecting concurrent updated of
	195	* each node is placed in a separate hash table indexed by node address.
	196	* For the pigeon configuration, the number of children is also kept in
	197	* a separate hash table, indexed by node address, because it is only
	198	* required for updates.
e5227865	199	*/
1db4943c	200
ff38c745 MD	201	#define DECLARE_LINEAR_NODE(index) \
	202	struct { \
	203	uint8_t nr_child; \
	204	uint8_t child_value[ja_type_## index ##_max_linear_child]; \
	205	struct rcu_ja_node_flag *child_ptr[ja_type_## index ##_max_linear_child]; \
	206	}
	207
	208	#define DECLARE_POOL_NODE(index) \
	209	struct { \
	210	struct { \
	211	uint8_t nr_child; \
	212	uint8_t child_value[ja_type_## index ##_max_linear_child]; \
	213	struct rcu_ja_node_flag *child_ptr[ja_type_## index ##_max_linear_child]; \
	214	} linear[1U << ja_type_## index ##_nr_pool_order]; \
	215	}
1db4943c	216
e5227865	217	struct rcu_ja_node {
1db4943c MD	218	union {
	219	/* Linear configuration */
	220	DECLARE_LINEAR_NODE(0) conf_0;
	221	DECLARE_LINEAR_NODE(1) conf_1;
	222	DECLARE_LINEAR_NODE(2) conf_2;
	223	DECLARE_LINEAR_NODE(3) conf_3;
	224	DECLARE_LINEAR_NODE(4) conf_4;
	225
	226	/* Pool configuration */
	227	DECLARE_POOL_NODE(5) conf_5;
	228	DECLARE_POOL_NODE(6) conf_6;
	229
	230	/* Pigeon configuration */
	231	struct {
	232	struct rcu_ja_node_flag *child[ja_type_7_max_child];
	233	} conf_7;
	234	/* data aliasing nodes for computed accesses */
	235	uint8_t data[sizeof(struct rcu_ja_node_flag ) ja_type_7_max_child];
	236	} u;
e5227865 MD	237	};
e5227865 MD	238
d68c6810	239	static
8e519e3c MD	240	struct rcu_ja_node_flag ja_node_flag(struct rcu_ja_node node,
8e519e3c MD	241	unsigned int type)
d68c6810	242	{
1db4943c	243	assert(type < RCU_JA_NR_TYPES);
d68c6810 MD	244	return (struct rcu_ja_node_flag *) (((unsigned long) node) \| type);
	245	}
	246
	247	static
	248	unsigned int ja_node_type(struct rcu_ja_node_flag *node)
	249	{
	250	unsigned int type;
	251
	252	type = (unsigned int) ((unsigned long) node & JA_TYPE_MASK);
1db4943c	253	assert(type < RCU_JA_NR_TYPES);
d68c6810 MD	254	return type;
	255	}
	256
	257	static
	258	struct rcu_ja_node ja_node_ptr(struct rcu_ja_node_flag node)
	259	{
	260	return (struct rcu_ja_node *) (((unsigned long) node) \| JA_PTR_MASK);
	261	}
	262
	263	struct rcu_ja_node alloc_rcu_ja_node(struct rcu_ja_type ja_type)
e5227865	264	{
1db4943c	265	return calloc(1U << ja_type->order, sizeof(char));
e5227865 MD	266	}
	267
	268	void free_rcu_ja_node(struct rcu_ja_node *node)
	269	{
	270	free(node);
	271	}
	272
d68c6810 MD	273	#define __JA_ALIGN_MASK(v, mask) (((v) + (mask)) & ~(mask))
	274	#define JA_ALIGN(v, align) __JA_ALIGN_MASK(v, (typeof(v)) (align) - 1)
	275	#define __JA_FLOOR_MASK(v, mask) ((v) & ~(mask))
	276	#define JA_FLOOR(v, align) __JA_FLOOR_MASK(v, (typeof(v)) (align) - 1)
	277
	278	static
1db4943c	279	uint8_t align_ptr_size(uint8_t ptr)
d68c6810	280	{
1db4943c	281	return (uint8_t ) JA_ALIGN((unsigned long) ptr, sizeof(void ));
d68c6810 MD	282	}
	283
	284	static
	285	struct rcu_ja_node_flag ja_linear_node_get_nth(const struct rcu_ja_type type,
8e519e3c MD	286	struct rcu_ja_node *node,
8e519e3c MD	287	uint8_t n)
d68c6810 MD	288	{
	289	uint8_t nr_child;
	290	uint8_t *values;
1db4943c	291	struct rcu_ja_node_flag **pointers;
d68c6810 MD	292	struct rcu_ja_node_flag *ptr;
	293	unsigned int i;
	294
8e519e3c	295	assert(type->type_class == RCU_JA_LINEAR \|\| type->type_class == RCU_JA_POOL);
d68c6810	296
1db4943c	297	nr_child = node->u.data[0];
d68c6810	298	cmm_smp_rmb(); /* read nr_child before values */
8e519e3c MD	299	assert(nr_child <= type->max_linear_child);
8e519e3c MD	300	assert(type->type_class != RCU_JA_LINEAR \|\| nr_child >= type->min_child);
d68c6810	301
1db4943c	302	values = &node->u.data[1];
d68c6810 MD	303	for (i = 0; i < nr_child; i++) {
	304	if (values[i] == n)
	305	break;
	306	}
	307	if (i >= nr_child)
	308	return NULL;
	309	cmm_smp_rmb(); /* read values before pointer */
8e519e3c	310	pointers = (struct rcu_ja_node_flag **) align_ptr_size(&values[type->max_linear_child]);
d68c6810 MD	311	ptr = pointers[i];
	312	assert(ja_node_ptr(ptr) != NULL);
	313	return ptr;
	314	}
	315
d68c6810	316	static
fd800776	317	struct rcu_ja_node_flag ja_pool_node_get_nth(const struct rcu_ja_type type,
8e519e3c MD	318	struct rcu_ja_node *node,
8e519e3c MD	319	uint8_t n)
d68c6810	320	{
fd800776	321	struct rcu_ja_node *linear;
d68c6810	322
fd800776 MD	323	assert(type->type_class == RCU_JA_POOL);
fd800776 MD	324	linear = (struct rcu_ja_node *)
1db4943c	325	&node->u.data[((unsigned long) n >> (CHAR_BIT - type->nr_pool_order)) << type->pool_size_order];
8e519e3c	326	return ja_linear_node_get_nth(type, linear, n);
d68c6810 MD	327	}
	328
	329	static
	330	struct rcu_ja_node_flag ja_pigeon_node_get_nth(const struct rcu_ja_type type,
8e519e3c MD	331	struct rcu_ja_node *node,
8e519e3c MD	332	uint8_t n)
d68c6810 MD	333	{
d68c6810 MD	334	assert(type->type_class == RCU_JA_PIGEON);
1db4943c	335	return ((struct rcu_ja_node_flag **) node->u.data)[n];
d68c6810 MD	336	}
	337
	338	/* ja_node_get_nth: get nth item from a node */
	339	static
	340	struct rcu_ja_node_flag ja_node_get_nth(struct rcu_ja_node_flag node_flag,
8e519e3c	341	uint8_t n)
d68c6810 MD	342	{
	343	unsigned int type_index;
	344	struct rcu_ja_node *node;
	345	const struct rcu_ja_type *type;
	346
	347	node_flag = rcu_dereference(node_flag);
	348	node = ja_node_ptr(node_flag);
	349	assert(node != NULL);
	350	type_index = ja_node_type(node_flag);
	351	type = &ja_types[type_index];
	352
	353	switch (type->type_class) {
	354	case RCU_JA_LINEAR:
	355	return ja_linear_node_get_nth(type, node, n);
fd800776 MD	356	case RCU_JA_POOL:
fd800776 MD	357	return ja_pool_node_get_nth(type, node, n);
d68c6810 MD	358	case RCU_JA_PIGEON:
	359	return ja_pigeon_node_get_nth(type, node, n);
	360	default:
	361	assert(0);
	362	return (void *) -1UL;
	363	}
	364	}
	365
8e519e3c MD	366	static
	367	int ja_linear_node_set_nth(const struct rcu_ja_type *type,
	368	struct rcu_ja_node *node,
	369	uint8_t n,
	370	struct rcu_ja_node_flag *child_node_flag)
	371	{
	372	uint8_t nr_child;
	373	uint8_t values, nr_child_ptr;
	374	struct rcu_ja_node_flag **pointers;
	375	unsigned int i;
	376
	377	assert(type->type_class == RCU_JA_LINEAR \|\| type->type_class == RCU_JA_POOL);
	378
	379	nr_child_ptr = &node->u.data[0];
	380	nr_child = *nr_child_ptr;
	381	assert(nr_child <= type->max_linear_child);
	382	assert(type->type_class != RCU_JA_LINEAR \|\| nr_child >= type->min_child);
	383
	384	values = &node->u.data[1];
	385	for (i = 0; i < nr_child; i++) {
	386	if (values[i] == n)
	387	return -EEXIST;
	388	}
	389	if (nr_child >= type->max_linear_child) {
	390	/* No space left in this node type */
	391	return -ENOSPC;
	392	}
	393	pointers = (struct rcu_ja_node_flag **) align_ptr_size(&values[type->max_linear_child]);
	394	pointers[nr_child] = child_node_flag;
	395	(*nr_child_ptr)++;
	396	return 0;
	397	}
	398
	399	static
	400	int ja_pool_node_set_nth(const struct rcu_ja_type *type,
	401	struct rcu_ja_node *node,
	402	uint8_t n,
	403	struct rcu_ja_node_flag *child_node_flag)
	404	{
	405	struct rcu_ja_node *linear;
	406
	407	assert(type->type_class == RCU_JA_POOL);
	408	linear = (struct rcu_ja_node *)
	409	&node->u.data[((unsigned long) n >> (CHAR_BIT - type->nr_pool_order)) << type->pool_size_order];
	410	return ja_linear_node_set_nth(type, linear, n, child_node_flag);
	411	}
	412
	413	static
	414	int ja_pigeon_node_set_nth(const struct rcu_ja_type *type,
	415	struct rcu_ja_node *node,
	416	uint8_t n,
	417	struct rcu_ja_node_flag *child_node_flag)
	418	{
	419	struct rcu_ja_node_flag **ptr;
	420
	421	assert(type->type_class == RCU_JA_PIGEON);
	422	ptr = &((struct rcu_ja_node_flag **) node->u.data)[n];
	423	if (*ptr != NULL)
	424	return -EEXIST;
	425	rcu_assign_pointer(*ptr, child_node_flag);
	426	return 0;
	427	}
	428
d68c6810	429	/*
8e519e3c MD	430	* ja_node_set_nth: set nth item within a node. Return an error
	431	* (negative error value) if it is already there.
	432	* TODO: exclusive access on node.
d68c6810	433	*/
8e519e3c MD	434	static
	435	int ja_node_set_nth(struct rcu_ja_node_flag *node_flag, uint8_t n,
	436	struct rcu_ja_node_flag *child_node_flag)
	437	{
	438	unsigned int type_index;
	439	struct rcu_ja_node *node;
	440	const struct rcu_ja_type *type;
e5227865	441
8e519e3c MD	442	node = ja_node_ptr(node_flag);
	443	assert(node != NULL);
	444	type_index = ja_node_type(node_flag);
	445	type = &ja_types[type_index];
	446
	447	switch (type->type_class) {
	448	case RCU_JA_LINEAR:
	449	return ja_linear_node_set_nth(type, node, n,
	450	child_node_flag);
	451	case RCU_JA_POOL:
	452	return ja_pool_node_set_nth(type, node, n,
	453	child_node_flag);
	454	case RCU_JA_PIGEON:
	455	return ja_pigeon_node_set_nth(type, node, n,
	456	child_node_flag);
	457	default:
	458	assert(0);
	459	return -EINVAL;
	460	}
	461
	462	return 0;
	463	}