X-Git-Url: http://git.lttng.org./?a=blobdiff_plain;f=rcuja%2Frcuja.c;h=34f3191a39037c24a058d33f0ebfabc405c0a82c;hb=b1a90ce30f17800630d578f32a05c2ad5eac0cae;hp=75113954ccdb9dee09193a41321002b623bd6cfd;hpb=582a6ade5032f98b788f1d8ddae97d44acf46715;p=userspace-rcu.git

diff --git a/rcuja/rcuja.c b/rcuja/rcuja.c
index 7511395..34f3191 100644
--- a/rcuja/rcuja.c
+++ b/rcuja/rcuja.c
@@ -24,6 +24,7 @@
 #include <stdint.h>
 #include <errno.h>
 #include <limits.h>
+#include <string.h>
 #include <urcu/rcuja.h>
 #include <urcu/compiler.h>
 #include <urcu/arch.h>
@@ -35,6 +36,10 @@
 #include "rcuja-internal.h"
 #include "bitfield.h"
 
+#ifndef abs
+#define abs_int(a)	((int) (a) > 0 ? (int) (a) : -((int) (a)))
+#endif
+
 enum cds_ja_type_class {
 	RCU_JA_LINEAR = 0,	/* Type A */
 			/* 32-bit: 1 to 25 children, 8 to 128 bytes */
@@ -61,33 +66,6 @@ struct cds_ja_type {
 	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	(1UL << 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
-#define JA_LOG2_BITS_PER_BYTE	3U
-#define JA_BITS_PER_BYTE	(1U << JA_LOG2_BITS_PER_BYTE)
-
-#define JA_MAX_DEPTH	9	/* Maximum depth, including leafs */
-
-/*
- * Entry for NULL node is at index 8 of the table. It is never encoded
- * in flags.
- */
-#define NODE_INDEX_NULL		8
-
-/*
- * Number of removals needed on a fallback node before we try to shrink
- * it.
- */
-#define JA_FALLBACK_REMOVAL_COUNT	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
@@ -147,8 +125,8 @@ const struct cds_ja_type ja_types[] = {
 	{ .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.
+	 * Upon node removal below min_child, if child pool is filled
+	 * beyond capacity, we roll back to pigeon.
 	 */
 	{ .type_class = RCU_JA_PIGEON, .min_child = 89, .max_child = ja_type_7_max_child, .order = 10, },
 
@@ -195,8 +173,8 @@ const struct cds_ja_type ja_types[] = {
 	{ .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.
+	 * Upon node removal below min_child, if child pool is filled
+	 * beyond capacity, we roll back to pigeon.
 	 */
 	{ .type_class = RCU_JA_PIGEON, .min_child = 101, .max_child = ja_type_7_max_child, .order = 11, },
 
@@ -260,26 +238,23 @@ struct cds_ja_inode {
 	} u;
 };
 
-static
-struct cds_ja_inode_flag *ja_node_flag(struct cds_ja_inode *node,
-		unsigned long type)
-{
-	assert(type < (1UL << JA_TYPE_BITS));
-	return (struct cds_ja_inode_flag *) (((unsigned long) node) | type);
-}
+enum ja_recompact {
+	JA_RECOMPACT,
+	JA_RECOMPACT_ADD,
+	JA_RECOMPACT_DEL,
+};
 
 static
-struct cds_ja_inode *ja_node_ptr(struct cds_ja_inode_flag *node)
+struct cds_ja_inode *_ja_node_mask_ptr(struct cds_ja_inode_flag *node)
 {
 	return (struct cds_ja_inode *) (((unsigned long) node) & JA_PTR_MASK);
 }
 
-static
 unsigned long ja_node_type(struct cds_ja_inode_flag *node)
 {
 	unsigned long type;
 
-	if (ja_node_ptr(node) == NULL) {
+	if (_ja_node_mask_ptr(node) == NULL) {
 		return NODE_INDEX_NULL;
 	}
 	type = (unsigned int) ((unsigned long) node & JA_TYPE_MASK);
@@ -287,9 +262,42 @@ unsigned long ja_node_type(struct cds_ja_inode_flag *node)
 	return type;
 }
 
+struct cds_ja_inode *ja_node_ptr(struct cds_ja_inode_flag *node)
+{
+	unsigned long type_index = ja_node_type(node);
+	const struct cds_ja_type *type;
+
+	type = &ja_types[type_index];
+	switch (type->type_class) {
+	case RCU_JA_LINEAR:
+	case RCU_JA_PIGEON:	/* fall-through */
+	case RCU_JA_NULL:	/* fall-through */
+	default:		/* fall-through */
+		return _ja_node_mask_ptr(node);
+	case RCU_JA_POOL:
+		switch (type->nr_pool_order) {
+		case 1:
+			return (struct cds_ja_inode *) (((unsigned long) node) & ~(JA_POOL_1D_MASK | JA_TYPE_MASK));
+		case 2:
+			return (struct cds_ja_inode *) (((unsigned long) node) & ~(JA_POOL_2D_MASK | JA_POOL_1D_MASK | JA_TYPE_MASK));
+		default:
+			assert(0);
+		}
+	}
+}
+
 struct cds_ja_inode *alloc_cds_ja_node(const struct cds_ja_type *ja_type)
 {
-	return calloc(1U << ja_type->order, sizeof(char));
+	size_t len = 1U << ja_type->order;
+	void *p;
+	int ret;
+
+	ret = posix_memalign(&p, len, len);
+	if (ret || !p) {
+		return NULL;
+	}
+	memset(p, 0, len);
+	return p;
 }
 
 void free_cds_ja_node(struct cds_ja_inode *node)
@@ -313,7 +321,7 @@ uint8_t ja_linear_node_get_nr_child(const struct cds_ja_type *type,
 		struct cds_ja_inode *node)
 {
 	assert(type->type_class == RCU_JA_LINEAR || type->type_class == RCU_JA_POOL);
-	return CMM_LOAD_SHARED(node->u.data[0]);
+	return rcu_dereference(node->u.data[0]);
 }
 
 /*
@@ -325,6 +333,8 @@ static
 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;
@@ -345,13 +355,19 @@ struct cds_ja_inode_flag *ja_linear_node_get_nth(const struct cds_ja_type *type,
 		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]);
-	if (caa_unlikely(child_node_flag_ptr))
-		*child_node_flag_ptr = &pointers[i];
 	ptr = rcu_dereference(pointers[i]);
-	assert(ja_node_ptr(ptr) != NULL);
+	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;
 }
 
@@ -377,19 +393,43 @@ void ja_linear_node_get_ith_pos(const struct cds_ja_type *type,
 static
 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 *node_flag,
 		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;
 
 	assert(type->type_class == RCU_JA_POOL);
-	/*
-	 * TODO: currently, we select the pool by highest bits. We
-	 * should support various encodings.
-	 */
-	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);
+
+	switch (type->nr_pool_order) {
+	case 1:
+	{
+		unsigned long bitsel, index;
+
+		bitsel = ja_node_pool_1d_bitsel(node_flag);
+		assert(bitsel < CHAR_BIT);
+		index = ((unsigned long) n >> bitsel) & type->nr_pool_order;
+		linear = (struct cds_ja_inode *) &node->u.data[index << type->pool_size_order];
+		break;
+	}
+	case 2:
+	{
+		/*
+		 * TODO: currently, we select the pool by highest bits. We
+		 * should support various encodings.
+		 */
+		linear = (struct cds_ja_inode *)
+			&node->u.data[((unsigned long) n >> (CHAR_BIT - type->nr_pool_order)) << type->pool_size_order];
+		break;
+	}
+	default:
+		linear = NULL;
+		assert(0);
+	}
+	return ja_linear_node_get_nth(type, linear, child_node_flag_ptr,
+		child_node_flag_v, node_flag_ptr, n);
 }
 
 static
@@ -406,17 +446,33 @@ 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_flag *ja_pigeon_node_get_ith_pos(const struct cds_ja_type *type,
+		struct cds_ja_inode *node,
+		uint8_t i)
+{
+	return ja_pigeon_node_get_nth(type, node, NULL, NULL, NULL, i);
 }
 
 /*
@@ -424,8 +480,10 @@ struct cds_ja_inode_flag *ja_pigeon_node_get_nth(const struct cds_ja_type *type,
  * 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;
@@ -440,31 +498,22 @@ struct cds_ja_inode_flag * ja_node_get_nth(struct cds_ja_inode_flag *node_flag,
 	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);
+		return ja_pool_node_get_nth(type, node, node_flag,
+				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;
 	}
 }
 
-/*
- * TODO: use ja_get_nr_child to monitor limits triggering shrink
- * recompaction.
- * Also use ja_get_nr_child to make the difference between resize and
- * pool change of compaction bit(s).
- */
-static
-unsigned int ja_get_nr_child(struct cds_ja_shadow_node *shadow_node)
-{
-	return shadow_node->nr_child;
-}
-
 static
 int ja_linear_node_set_nth(const struct cds_ja_type *type,
 		struct cds_ja_inode *node,
@@ -475,7 +524,7 @@ int ja_linear_node_set_nth(const struct cds_ja_type *type,
 	uint8_t nr_child;
 	uint8_t *values, *nr_child_ptr;
 	struct cds_ja_inode_flag **pointers;
-	unsigned int i;
+	unsigned int i, unused = 0;
 
 	assert(type->type_class == RCU_JA_LINEAR || type->type_class == RCU_JA_POOL);
 
@@ -485,20 +534,35 @@ int ja_linear_node_set_nth(const struct cds_ja_type *type,
 	assert(nr_child <= type->max_linear_child);
 
 	values = &node->u.data[1];
+	pointers = (struct cds_ja_inode_flag **) align_ptr_size(&values[type->max_linear_child]);
+	/* Check if node value is already populated */
 	for (i = 0; i < nr_child; i++) {
-		if (values[i] == n)
-			return -EEXIST;
+		if (values[i] == n) {
+			if (pointers[i])
+				return -EEXIST;
+			else
+				break;
+		} else {
+			if (!pointers[i])
+				unused++;
+		}
 	}
-	if (nr_child >= type->max_linear_child) {
-		/* No space left in this node type */
-		return -ENOSPC;
+	if (i == nr_child && nr_child >= type->max_linear_child) {
+		if (unused)
+			return -ERANGE;	/* recompact node */
+		else
+			return -ENOSPC;	/* No space left in this node type */
+	}
+
+	assert(pointers[i] == NULL);
+	rcu_assign_pointer(pointers[i], child_node_flag);
+	/* If we expanded the nr_child, increment it */
+	if (i == nr_child) {
+		CMM_STORE_SHARED(values[nr_child], n);
+		/* write pointer and value before nr_child */
+		cmm_smp_wmb();
+		CMM_STORE_SHARED(*nr_child_ptr, nr_child + 1);
 	}
-	pointers = (struct cds_ja_inode_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);
 	shadow_node->nr_child++;
 	dbg_printf("linear set nth: %u child, shadow: %u child, for node %p shadow %p\n",
 		(unsigned int) CMM_LOAD_SHARED(*nr_child_ptr),
@@ -511,6 +575,7 @@ int ja_linear_node_set_nth(const struct cds_ja_type *type,
 static
 int ja_pool_node_set_nth(const struct cds_ja_type *type,
 		struct cds_ja_inode *node,
+		struct cds_ja_inode_flag *node_flag,
 		struct cds_ja_shadow_node *shadow_node,
 		uint8_t n,
 		struct cds_ja_inode_flag *child_node_flag)
@@ -518,8 +583,33 @@ int ja_pool_node_set_nth(const struct cds_ja_type *type,
 	struct cds_ja_inode *linear;
 
 	assert(type->type_class == RCU_JA_POOL);
-	linear = (struct cds_ja_inode *)
-		&node->u.data[((unsigned long) n >> (CHAR_BIT - type->nr_pool_order)) << type->pool_size_order];
+
+	switch (type->nr_pool_order) {
+	case 1:
+	{
+		unsigned long bitsel, index;
+
+		bitsel = ja_node_pool_1d_bitsel(node_flag);
+		assert(bitsel < CHAR_BIT);
+		index = ((unsigned long) n >> bitsel) & type->nr_pool_order;
+		linear = (struct cds_ja_inode *) &node->u.data[index << type->pool_size_order];
+		break;
+	}
+	case 2:
+	{
+		/*
+		 * TODO: currently, we select the pool by highest bits. We
+		 * should support various encodings.
+		 */
+		linear = (struct cds_ja_inode *)
+			&node->u.data[((unsigned long) n >> (CHAR_BIT - type->nr_pool_order)) << type->pool_size_order];
+		break;
+	}
+	default:
+		linear = NULL;
+		assert(0);
+	}
+
 	return ja_linear_node_set_nth(type, linear, shadow_node,
 			n, child_node_flag);
 }
@@ -545,11 +635,11 @@ int ja_pigeon_node_set_nth(const struct cds_ja_type *type,
 /*
  * _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(const struct cds_ja_type *type,
 		struct cds_ja_inode *node,
+		struct cds_ja_inode_flag *node_flag,
 		struct cds_ja_shadow_node *shadow_node,
 		uint8_t n,
 		struct cds_ja_inode_flag *child_node_flag)
@@ -559,7 +649,7 @@ int _ja_node_set_nth(const struct cds_ja_type *type,
 		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, shadow_node, n,
+		return ja_pool_node_set_nth(type, node, node_flag, shadow_node, n,
 				child_node_flag);
 	case RCU_JA_PIGEON:
 		return ja_pigeon_node_set_nth(type, node, shadow_node, n,
@@ -574,55 +664,350 @@ int _ja_node_set_nth(const struct cds_ja_type *type,
 	return 0;
 }
 
+static
+int ja_linear_node_clear_ptr(const struct cds_ja_type *type,
+		struct cds_ja_inode *node,
+		struct cds_ja_shadow_node *shadow_node,
+		struct cds_ja_inode_flag **node_flag_ptr)
+{
+	uint8_t nr_child;
+	uint8_t *nr_child_ptr;
+
+	assert(type->type_class == RCU_JA_LINEAR || type->type_class == RCU_JA_POOL);
+
+	nr_child_ptr = &node->u.data[0];
+	dbg_printf("linear clear ptr: nr_child_ptr %p\n", nr_child_ptr);
+	nr_child = *nr_child_ptr;
+	assert(nr_child <= type->max_linear_child);
+
+	if (shadow_node->fallback_removal_count) {
+		shadow_node->fallback_removal_count--;
+	} else {
+		if (shadow_node->nr_child <= type->min_child) {
+			/* We need to try recompacting the node */
+			return -EFBIG;
+		}
+	}
+	assert(*node_flag_ptr != NULL);
+	rcu_assign_pointer(*node_flag_ptr, NULL);
+	/*
+	 * Value and nr_child are never changed (would cause ABA issue).
+	 * Instead, we leave the pointer to NULL and recompact the node
+	 * once in a while. It is allowed to set a NULL pointer to a new
+	 * value without recompaction though.
+	 * Only update the shadow node accounting.
+	 */
+	shadow_node->nr_child--;
+	dbg_printf("linear clear ptr: %u child, shadow: %u child, for node %p shadow %p\n",
+		(unsigned int) CMM_LOAD_SHARED(*nr_child_ptr),
+		(unsigned int) shadow_node->nr_child,
+		node, shadow_node);
+
+	return 0;
+}
+
+static
+int ja_pool_node_clear_ptr(const struct cds_ja_type *type,
+		struct cds_ja_inode *node,
+		struct cds_ja_shadow_node *shadow_node,
+		struct cds_ja_inode_flag **node_flag_ptr,
+		uint8_t n)
+{
+	struct cds_ja_inode *linear;
+
+	assert(type->type_class == RCU_JA_POOL);
+	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_clear_ptr(type, linear, shadow_node, node_flag_ptr);
+}
+
+static
+int ja_pigeon_node_clear_ptr(const struct cds_ja_type *type,
+		struct cds_ja_inode *node,
+		struct cds_ja_shadow_node *shadow_node,
+		struct cds_ja_inode_flag **node_flag_ptr)
+{
+	assert(type->type_class == RCU_JA_PIGEON);
+	dbg_printf("ja_pigeon_node_clear_ptr: clearing ptr: %p\n", *node_flag_ptr);
+	rcu_assign_pointer(*node_flag_ptr, NULL);
+	shadow_node->nr_child--;
+	return 0;
+}
+
+/*
+ * _ja_node_clear_ptr: clear ptr item within a node. Return an error
+ * (negative error value) if it is not found (-ENOENT).
+ */
+static
+int _ja_node_clear_ptr(const struct cds_ja_type *type,
+		struct cds_ja_inode *node,
+		struct cds_ja_shadow_node *shadow_node,
+		struct cds_ja_inode_flag **node_flag_ptr,
+		uint8_t n)
+{
+	switch (type->type_class) {
+	case RCU_JA_LINEAR:
+		return ja_linear_node_clear_ptr(type, node, shadow_node, node_flag_ptr);
+	case RCU_JA_POOL:
+		return ja_pool_node_clear_ptr(type, node, shadow_node, node_flag_ptr, n);
+	case RCU_JA_PIGEON:
+		return ja_pigeon_node_clear_ptr(type, node, shadow_node, node_flag_ptr);
+	case RCU_JA_NULL:
+		return -ENOENT;
+	default:
+		assert(0);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+/*
+ * Calculate bit distribution. Returns the bit (0 to 7) that splits the
+ * distribution in two sub-distributions containing as much elements one
+ * compared to the other.
+ */
+static
+unsigned int ja_node_sum_distribution_1d(enum ja_recompact mode,
+		struct cds_ja *ja,
+		unsigned int type_index,
+		const struct cds_ja_type *type,
+		struct cds_ja_inode *node,
+		struct cds_ja_shadow_node *shadow_node,
+		uint8_t n,
+		struct cds_ja_inode_flag *child_node_flag,
+		struct cds_ja_inode_flag **nullify_node_flag_ptr)
+{
+	uint8_t nr_one[JA_BITS_PER_BYTE];
+	unsigned int bitsel = 0, bit_i, overall_best_distance = UINT_MAX;
+	unsigned int distrib_nr_child = 0;
+
+	memset(nr_one, 0, sizeof(nr_one));
+
+	switch (type->type_class) {
+	case RCU_JA_LINEAR:
+	{
+		uint8_t nr_child =
+			ja_linear_node_get_nr_child(type, node);
+		unsigned int i;
+
+		for (i = 0; i < nr_child; i++) {
+			struct cds_ja_inode_flag *iter;
+			unsigned int bit;
+			uint8_t v;
+
+			ja_linear_node_get_ith_pos(type, node, i, &v, &iter);
+			if (!iter)
+				continue;
+			if (mode == JA_RECOMPACT_DEL && *nullify_node_flag_ptr == iter)
+				continue;
+			for (bit = 0; bit < JA_BITS_PER_BYTE; bit++) {
+				if (v & (1U << bit))
+					nr_one[bit]++;
+			}
+			distrib_nr_child++;
+		}
+		break;
+	}
+	case RCU_JA_POOL:
+	{
+		unsigned int pool_nr;
+
+		for (pool_nr = 0; pool_nr < (1U << type->nr_pool_order); pool_nr++) {
+			struct cds_ja_inode *pool =
+				ja_pool_node_get_ith_pool(type,
+					node, pool_nr);
+			uint8_t nr_child =
+				ja_linear_node_get_nr_child(type, pool);
+			unsigned int j;
+
+			for (j = 0; j < nr_child; j++) {
+				struct cds_ja_inode_flag *iter;
+				unsigned int bit;
+				uint8_t v;
+
+				ja_linear_node_get_ith_pos(type, pool,
+						j, &v, &iter);
+				if (!iter)
+					continue;
+				if (mode == JA_RECOMPACT_DEL && *nullify_node_flag_ptr == iter)
+					continue;
+				for (bit = 0; bit < JA_BITS_PER_BYTE; bit++) {
+					if (v & (1U << bit))
+						nr_one[bit]++;
+				}
+				distrib_nr_child++;
+			}
+		}
+		break;
+	}
+	case RCU_JA_PIGEON:
+	{
+		uint8_t nr_child;
+		unsigned int i;
+
+		assert(mode == JA_RECOMPACT_DEL);
+		nr_child = shadow_node->nr_child;
+		for (i = 0; i < nr_child; i++) {
+			struct cds_ja_inode_flag *iter;
+			unsigned int bit;
+
+			iter = ja_pigeon_node_get_ith_pos(type, node, i);
+			if (!iter)
+				continue;
+			if (mode == JA_RECOMPACT_DEL && *nullify_node_flag_ptr == iter)
+				continue;
+			for (bit = 0; bit < JA_BITS_PER_BYTE; bit++) {
+				if (i & (1U << bit))
+					nr_one[bit]++;
+			}
+			distrib_nr_child++;
+		}
+		break;
+	}
+	case RCU_JA_NULL:
+		assert(mode == JA_RECOMPACT_ADD);
+		break;
+	default:
+		assert(0);
+		break;
+	}
+
+	if (mode == JA_RECOMPACT_ADD) {
+		unsigned int bit;
+
+		for (bit = 0; bit < JA_BITS_PER_BYTE; bit++) {
+			if (n & (1U << bit))
+				nr_one[bit]++;
+		}
+		distrib_nr_child++;
+	}
+
+	/*
+	 * The best bit selector is that for which the number of ones is
+	 * closest to half of the number of children in the
+	 * distribution.
+	 */
+	for (bit_i = 0; bit_i < JA_BITS_PER_BYTE; bit_i++) {
+		unsigned int distance_to_best;
+
+		distance_to_best = abs_int(nr_one[bit_i] - (distrib_nr_child >> 1U));
+		if (distance_to_best < overall_best_distance) {
+			overall_best_distance = distance_to_best;
+			bitsel = bit_i;
+		}
+	}
+	dbg_printf("1 dimension pool bit selection: (%u)\n", bitsel);
+	return bitsel;
+}
+
 /*
  * ja_node_recompact_add: recompact a node, adding a new child.
- * TODO: for pool type, take selection bit(s) into account.
- * Return 0 on success, -ENOENT if need to retry, or other negative
+ * Return 0 on success, -EAGAIN if need to retry, or other negative
  * error value otherwise.
  */
 static
-int ja_node_recompact_add(struct cds_ja *ja,
+int ja_node_recompact(enum ja_recompact mode,
+		struct cds_ja *ja,
 		unsigned int old_type_index,
 		const struct cds_ja_type *old_type,
 		struct cds_ja_inode *old_node,
 		struct cds_ja_shadow_node *shadow_node,
-		struct cds_ja_inode_flag **old_node_flag, uint8_t n,
-		struct cds_ja_inode_flag *child_node_flag)
+		struct cds_ja_inode_flag **old_node_flag_ptr, uint8_t n,
+		struct cds_ja_inode_flag *child_node_flag,
+		struct cds_ja_inode_flag **nullify_node_flag_ptr)
 {
 	unsigned int new_type_index;
 	struct cds_ja_inode *new_node;
-	struct cds_ja_shadow_node *new_shadow_node;
+	struct cds_ja_shadow_node *new_shadow_node = NULL;
 	const struct cds_ja_type *new_type;
-	struct cds_ja_inode_flag *new_node_flag;
+	struct cds_ja_inode_flag *new_node_flag, *old_node_flag;
 	int ret;
 	int fallback = 0;
 
-	if (!shadow_node || old_type_index == NODE_INDEX_NULL) {
-		new_type_index = 0;
-	} else {
-		new_type_index = old_type_index + 1;
+	old_node_flag = *old_node_flag_ptr;
+
+	switch (mode) {
+	case JA_RECOMPACT:
+		new_type_index = old_type_index;
+		break;
+	case JA_RECOMPACT_ADD:
+		if (!shadow_node || old_type_index == NODE_INDEX_NULL) {
+			new_type_index = 0;
+		} else {
+			new_type_index = old_type_index + 1;
+		}
+		break;
+	case JA_RECOMPACT_DEL:
+		if (old_type_index == 0) {
+			new_type_index = NODE_INDEX_NULL;
+		} else {
+			new_type_index = old_type_index - 1;
+		}
+		break;
+	default:
+		assert(0);
 	}
 
 retry:		/* for fallback */
 	dbg_printf("Recompact from type %d to type %d\n",
 			old_type_index, new_type_index);
 	new_type = &ja_types[new_type_index];
-	new_node = alloc_cds_ja_node(new_type);
-	if (!new_node)
-		return -ENOMEM;
-	new_node_flag = ja_node_flag(new_node, new_type_index);
-
-	dbg_printf("Recompact inherit lock from %p\n", shadow_node);
-	new_shadow_node = rcuja_shadow_set(ja->ht, new_node, shadow_node);
-	if (!new_shadow_node) {
-		free(new_node);
-		return -ENOMEM;
+	if (new_type_index != NODE_INDEX_NULL) {
+		new_node = alloc_cds_ja_node(new_type);
+		if (!new_node)
+			return -ENOMEM;
+
+		if (new_type->type_class == RCU_JA_POOL) {
+			switch (new_type->nr_pool_order) {
+			case 1:
+			{
+				unsigned int node_distrib_bitsel = 0;
+				node_distrib_bitsel =
+					ja_node_sum_distribution_1d(mode, ja,
+						old_type_index, old_type,
+						old_node, shadow_node,
+						n, child_node_flag,
+						nullify_node_flag_ptr);
+				assert(!((unsigned long) new_node & JA_POOL_1D_MASK));
+				new_node_flag = ja_node_flag_pool_1d(new_node,
+					new_type_index, node_distrib_bitsel);
+				break;
+			}
+			case 2:
+			{
+				/* TODO: pool order 2 in 2d */
+				assert(!((unsigned long) new_node & JA_POOL_1D_MASK));
+				assert(!((unsigned long) new_node & JA_POOL_2D_MASK));
+				new_node_flag = ja_node_flag(new_node, new_type_index);
+				break;
+			}
+			default:
+				assert(0);
+			}
+		} else {
+			new_node_flag = ja_node_flag(new_node, new_type_index);
+		}
+
+		dbg_printf("Recompact inherit lock from %p\n", shadow_node);
+		new_shadow_node = rcuja_shadow_set(ja->ht, new_node_flag, shadow_node, ja);
+		if (!new_shadow_node) {
+			free(new_node);
+			return -ENOMEM;
+		}
+		if (fallback)
+			new_shadow_node->fallback_removal_count =
+						JA_FALLBACK_REMOVAL_COUNT;
+	} else {
+		new_node = NULL;
+		new_node_flag = NULL;
 	}
-	if (fallback)
-		new_shadow_node->fallback_removal_count =
-					JA_FALLBACK_REMOVAL_COUNT;
 
-	assert(old_type->type_class != RCU_JA_PIGEON);
+	assert(mode != JA_RECOMPACT_ADD || old_type->type_class != RCU_JA_PIGEON);
+
+	if (new_type_index == NODE_INDEX_NULL)
+		goto skip_copy;
+
 	switch (old_type->type_class) {
 	case RCU_JA_LINEAR:
 	{
@@ -637,7 +1022,9 @@ retry:		/* for fallback */
 			ja_linear_node_get_ith_pos(old_type, old_node, i, &v, &iter);
 			if (!iter)
 				continue;
-			ret = _ja_node_set_nth(new_type, new_node,
+			if (mode == JA_RECOMPACT_DEL && *nullify_node_flag_ptr == iter)
+				continue;
+			ret = _ja_node_set_nth(new_type, new_node, new_node_flag,
 					new_shadow_node,
 					v, iter);
 			if (new_type->type_class == RCU_JA_POOL && ret) {
@@ -667,7 +1054,9 @@ retry:		/* for fallback */
 						j, &v, &iter);
 				if (!iter)
 					continue;
-				ret = _ja_node_set_nth(new_type, new_node,
+				if (mode == JA_RECOMPACT_DEL && *nullify_node_flag_ptr == iter)
+					continue;
+				ret = _ja_node_set_nth(new_type, new_node, new_node_flag,
 						new_shadow_node,
 						v, iter);
 				if (new_type->type_class == RCU_JA_POOL
@@ -680,25 +1069,65 @@ retry:		/* for fallback */
 		break;
 	}
 	case RCU_JA_NULL:
-		/* Nothing to copy */
+		assert(mode == JA_RECOMPACT_ADD);
 		break;
 	case RCU_JA_PIGEON:
+	{
+		uint8_t nr_child;
+		unsigned int i;
+
+		assert(mode == JA_RECOMPACT_DEL);
+		nr_child = shadow_node->nr_child;
+		for (i = 0; i < nr_child; i++) {
+			struct cds_ja_inode_flag *iter;
+
+			iter = ja_pigeon_node_get_ith_pos(old_type, old_node, i);
+			if (!iter)
+				continue;
+			if (mode == JA_RECOMPACT_DEL && *nullify_node_flag_ptr == iter)
+				continue;
+			ret = _ja_node_set_nth(new_type, new_node, new_node_flag,
+					new_shadow_node,
+					i, iter);
+			if (new_type->type_class == RCU_JA_POOL && ret) {
+				goto fallback_toosmall;
+			}
+			assert(!ret);
+		}
+		break;
+	}
 	default:
 		assert(0);
 		ret = -EINVAL;
 		goto end;
 	}
-
-	/* add node */
-	ret = _ja_node_set_nth(new_type, new_node,
-			new_shadow_node,
-			n, child_node_flag);
-	assert(!ret);
-	/* Return pointer to new recompacted new through old_node_flag */
-	*old_node_flag = new_node_flag;
+skip_copy:
+
+	if (mode == JA_RECOMPACT_ADD) {
+		/* add node */
+		ret = _ja_node_set_nth(new_type, new_node, new_node_flag,
+				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 */
+	*old_node_flag_ptr = new_node_flag;
 	if (old_node) {
-		ret = rcuja_shadow_clear(ja->ht, old_node, shadow_node,
-				RCUJA_SHADOW_CLEAR_FREE_NODE);
+		int flags;
+
+		flags = RCUJA_SHADOW_CLEAR_FREE_NODE;
+		/*
+		 * It is OK to free the lock associated with a node
+		 * going to NULL, since we are holding the parent lock.
+		 * This synchronizes removal with re-add of that node.
+		 */
+		if (new_type_index == NODE_INDEX_NULL)
+			flags = RCUJA_SHADOW_CLEAR_FREE_LOCK;
+		ret = rcuja_shadow_clear(ja->ht, old_node_flag, shadow_node,
+				flags);
 		assert(!ret);
 	}
 
@@ -708,11 +1137,12 @@ end:
 
 fallback_toosmall:
 	/* fallback if next pool is too small */
-	ret = rcuja_shadow_clear(ja->ht, new_node, new_shadow_node,
+	assert(new_shadow_node);
+	ret = rcuja_shadow_clear(ja->ht, new_node_flag, new_shadow_node,
 			RCUJA_SHADOW_CLEAR_FREE_NODE);
 	assert(!ret);
 
-	/* Last type: pigeon */
+	/* Choose fallback type: pigeon */
 	new_type_index = (1UL << JA_TYPE_BITS) - 1;
 	dbg_printf("Fallback to type %d\n", new_type_index);
 	uatomic_inc(&ja->nr_fallback);
@@ -721,7 +1151,7 @@ fallback_toosmall:
 }
 
 /*
- * Return 0 on success, -ENOENT if need to retry, or other negative
+ * Return 0 on success, -EAGAIN if need to retry, or other negative
  * error value otherwise.
  */
 static
@@ -741,44 +1171,85 @@ int ja_node_set_nth(struct cds_ja *ja,
 	node = ja_node_ptr(*node_flag);
 	type_index = ja_node_type(*node_flag);
 	type = &ja_types[type_index];
-	ret = _ja_node_set_nth(type, node, shadow_node,
+	ret = _ja_node_set_nth(type, node, *node_flag, shadow_node,
 			n, child_node_flag);
-	if (ret == -ENOSPC) {
+	switch (ret) {
+	case -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);
+		ret = ja_node_recompact(JA_RECOMPACT_ADD, ja, type_index, type, node,
+				shadow_node, node_flag, n, child_node_flag, NULL);
+		break;
+	case -ERANGE:
+		/* Node needs to be recompacted. */
+		ret = ja_node_recompact(JA_RECOMPACT, ja, type_index, type, node,
+				shadow_node, node_flag, n, child_node_flag, NULL);
+		break;
 	}
 	return ret;
 }
 
-struct cds_hlist_head *cds_ja_lookup(struct cds_ja *ja, uint64_t key)
+/*
+ * Return 0 on success, -EAGAIN if need to retry, or other negative
+ * error value otherwise.
+ */
+static
+int ja_node_clear_ptr(struct cds_ja *ja,
+		struct cds_ja_inode_flag **node_flag_ptr,	/* Pointer to location to nullify */
+		struct cds_ja_inode_flag **parent_node_flag_ptr,	/* Address of parent ptr in its parent */
+		struct cds_ja_shadow_node *shadow_node,		/* of parent */
+		uint8_t n)
+{
+	int ret;
+	unsigned int type_index;
+	const struct cds_ja_type *type;
+	struct cds_ja_inode *node;
+
+	dbg_printf("ja_node_clear_ptr for node %p, shadow %p, target ptr %p\n",
+		ja_node_ptr(*parent_node_flag_ptr), shadow_node, node_flag_ptr);
+
+	node = ja_node_ptr(*parent_node_flag_ptr);
+	type_index = ja_node_type(*parent_node_flag_ptr);
+	type = &ja_types[type_index];
+	ret = _ja_node_clear_ptr(type, node, shadow_node, node_flag_ptr, n);
+	if (ret == -EFBIG) {
+		/* Should to try recompaction. */
+		ret = ja_node_recompact(JA_RECOMPACT_DEL, ja, type_index, type, node,
+				shadow_node, parent_node_flag_ptr, n, NULL,
+				node_flag_ptr);
+	}
+	return ret;
+}
+
+struct cds_hlist_head cds_ja_lookup(struct cds_ja *ja, uint64_t key)
 {
 	unsigned int tree_depth, i;
 	struct cds_ja_inode_flag *node_flag;
+	struct cds_hlist_head head = { NULL };
 
 	if (caa_unlikely(key > ja->key_max))
-		return NULL;
+		return head;
 	tree_depth = ja->tree_depth;
 	node_flag = rcu_dereference(ja->root);
 
 	/* level 0: root node */
 	if (!ja_node_ptr(node_flag))
-		return NULL;
+		return head;
 
 	for (i = 1; i < tree_depth; i++) {
 		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);
 		if (!ja_node_ptr(node_flag))
-			return NULL;
+			return head;
 	}
 
 	/* Last level lookup succeded. We got an actual match. */
-	return (struct cds_hlist_head *) node_flag;
+	head.next = (struct cds_hlist_node *) node_flag;
+	return head;
 }
 
 /*
@@ -795,6 +1266,8 @@ struct cds_hlist_head *cds_ja_lookup(struct cds_ja *ja, uint64_t key)
  */
 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,
@@ -803,8 +1276,7 @@ int ja_attach_node(struct cds_ja *ja,
 		struct cds_ja_node *child_node)
 {
 	struct cds_ja_shadow_node *shadow_node = NULL,
-			*parent_shadow_node = NULL,
-			*iter_shadow_node;
+			*parent_shadow_node = NULL;
 	struct cds_ja_inode *node = ja_node_ptr(node_flag);
 	struct cds_ja_inode *parent_node = ja_node_ptr(parent_node_flag);
 	struct cds_hlist_head head;
@@ -817,35 +1289,46 @@ int ja_attach_node(struct cds_ja *ja,
 		level, node, node_flag);
 
 	assert(node);
-	shadow_node = rcuja_shadow_lookup_lock(ja->ht, node);
+	shadow_node = rcuja_shadow_lookup_lock(ja->ht, node_flag);
 	if (!shadow_node) {
-		ret = -ENOENT;
+		ret = -EAGAIN;
 		goto end;
 	}
 	if (parent_node) {
 		parent_shadow_node = rcuja_shadow_lookup_lock(ja->ht,
-						parent_node);
+						parent_node_flag);
 		if (!parent_shadow_node) {
-			ret = -ENOENT;
+			ret = -EAGAIN;
 			goto unlock_shadow;
 		}
 	}
 
+	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);
 	iter_node_flag = (struct cds_ja_inode_flag *) head.next;
 
-	/* Create shadow node for the leaf node */
-	dbg_printf("leaf shadow node creation\n");
-	iter_shadow_node = rcuja_shadow_set(ja->ht,
-			ja_node_ptr(iter_node_flag), NULL);
-	if (!iter_shadow_node) {
-		ret = -ENOMEM;
-		goto check_error;
-	}
-	created_nodes[nr_created_nodes++] = iter_node_flag;
-
 	for (i = ja->tree_depth; i > (int) level; i--) {
 		uint8_t iter_key;
 
@@ -881,8 +1364,8 @@ int ja_attach_node(struct cds_ja *ja,
 
 	/* 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;
@@ -897,12 +1380,13 @@ check_error:
 			if (i)
 				flags |= RCUJA_SHADOW_CLEAR_FREE_NODE;
 			tmpret = rcuja_shadow_clear(ja->ht,
-					ja_node_ptr(created_nodes[i]),
+					created_nodes[i],
 					NULL,
 					flags);
 			assert(!tmpret);
 		}
 	}
+unlock_parent:
 	if (parent_shadow_node)
 		rcuja_shadow_unlock(parent_shadow_node);
 unlock_shadow:
@@ -913,39 +1397,51 @@ end:
 }
 
 /*
- * Lock the hlist head shadow node mutex, and add node to list of
- * duplicates. Failure can happen if concurrent removal removes the last
- * node with same key before we get the lock.
+ * Lock the parent containing the hlist head pointer, and add node to list of
+ * duplicates. Failure can happen if concurrent update changes the
+ * parent before we get the lock. We return -EAGAIN in that case.
  * Return 0 on success, negative error value on failure.
  */
 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,
-		(struct cds_ja_inode *) head);
-	if (!shadow_node)
-		return -ENOENT;
+	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;
+	}
 	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:
@@ -954,20 +1450,25 @@ 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(*node_flag_ptr);
+	node_flag = rcu_dereference(ja->root);
 
 	/* Iterate on all internal levels */
 	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 == -ENOENT || ret == -EEXIST)
+			if (ret == -EAGAIN || ret == -EEXIST)
 				goto retry;
 			else
 				goto end;
@@ -976,10 +1477,14 @@ 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);
 	}
 
 	/*
@@ -987,21 +1492,342 @@ retry:
 	 * 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,
-			(struct cds_hlist_head *) ja_node_ptr(node_flag),
+			parent_node_flag,
+			node_flag_ptr,
+			node_flag,
+			(struct cds_hlist_head *) attach_node_flag_ptr,
 			new_node);
 	}
-	if (ret == -ENOENT)
+	if (ret == -EAGAIN || ret == -EEXIST)
 		goto retry;
 end:
 	return ret;
 }
 
+/*
+ * Note: there is no need to lookup the pointer address associated with
+ * each node's nth item after taking the lock: it's already been done by
+ * cds_ja_del while holding the rcu read-side lock, and our node rules
+ * 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,
+		struct cds_ja_inode_flag **snapshot,
+		struct cds_ja_inode_flag ***snapshot_ptr,
+		uint8_t *snapshot_n,
+		int nr_snapshot,
+		uint64_t key,
+		struct cds_ja_node *node)
+{
+	struct cds_ja_shadow_node *shadow_nodes[JA_MAX_DEPTH];
+	struct cds_ja_inode_flag **node_flag_ptr = NULL,
+			*parent_node_flag = NULL,
+			**parent_node_flag_ptr = NULL;
+	struct cds_ja_inode_flag *iter_node_flag;
+	int ret, i, nr_shadow = 0, nr_clear = 0, nr_branch = 0;
+	uint8_t n = 0;
+
+	assert(nr_snapshot == ja->tree_depth + 1);
+
+	/*
+	 * From the last internal level node going up, get the node
+	 * lock, check if the node has only one child left. If it is the
+	 * case, we continue iterating upward. When we reach a node
+	 * which has more that one child left, we lock the parent, and
+	 * proceed to the node deletion (removing its children too).
+	 */
+	for (i = nr_snapshot - 2; i >= 1; i--) {
+		struct cds_ja_shadow_node *shadow_node;
+
+		shadow_node = rcuja_shadow_lookup_lock(ja->ht,
+					snapshot[i]);
+		if (!shadow_node) {
+			ret = -EAGAIN;
+			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;
+		}
+
+		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) {
+			/* Lock parent and break */
+			shadow_node = rcuja_shadow_lookup_lock(ja->ht,
+					snapshot[i - 1]);
+			if (!shadow_node) {
+				ret = -EAGAIN;
+				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
+				 * to recompact parent.
+				 */
+				shadow_node = rcuja_shadow_lookup_lock(ja->ht,
+						snapshot[i - 2]);
+				if (!shadow_node) {
+					ret = -EAGAIN;
+					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 free lock here, because RCU read lock is held,
+	 * and free only performed in call_rcu.
+	 */
+
+	for (i = 0; i < nr_clear; i++) {
+		ret = rcuja_shadow_clear(ja->ht,
+				shadow_nodes[i]->node_flag,
+				shadow_nodes[i],
+				RCUJA_SHADOW_CLEAR_FREE_NODE
+				| RCUJA_SHADOW_CLEAR_FREE_LOCK);
+		assert(!ret);
+	}
+
+	iter_node_flag = parent_node_flag;
+	/* Remove from parent */
+	ret = ja_node_clear_ptr(ja,
+		node_flag_ptr, 		/* Pointer to location to nullify */
+		&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);
+	/* Update address of parent ptr in its parent */
+	rcu_assign_pointer(*parent_node_flag_ptr, iter_node_flag);
+
+end:
+	for (i = 0; i < nr_shadow; i++)
+		rcuja_shadow_unlock(shadow_nodes[i]);
+	return ret;
+}
+
+static
+int ja_unchain_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_ja_node *node)
+{
+	struct cds_ja_shadow_node *shadow_node;
+	struct cds_hlist_node *hlist_node;
+	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 (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, &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++;
+	}
+	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;
+}
+
+/*
+ * Called with RCU read lock held.
+ */
+int cds_ja_del(struct cds_ja *ja, uint64_t key,
+		struct cds_ja_node *node)
+{
+	unsigned int tree_depth, i;
+	struct cds_ja_inode_flag *snapshot[JA_MAX_DEPTH];
+	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,
+		**node_flag_ptr;
+	int nr_snapshot;
+	int ret;
+
+	if (caa_unlikely(key > ja->key_max))
+		return -EINVAL;
+	tree_depth = ja->tree_depth;
+
+retry:
+	nr_snapshot = 0;
+	dbg_printf("cds_ja_del attempt: key %" PRIu64 ", node %p\n",
+		key, node);
+
+	/* snapshot for level 0 is only for shadow node lookup */
+	snapshot_n[0] = 0;
+	snapshot_n[1] = 0;
+	snapshot_ptr[nr_snapshot] = NULL;
+	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++) {
+		uint8_t iter_key;
+
+		dbg_printf("cds_ja_del iter node_flag %p\n",
+				node_flag);
+		if (!ja_node_ptr(node_flag)) {
+			return -ENOENT;
+		}
+		iter_key = (uint8_t) (key >> (JA_BITS_PER_BYTE * (tree_depth - i - 1)));
+		snapshot_n[nr_snapshot + 1] = iter_key;
+		snapshot_ptr[nr_snapshot] = prev_node_flag_ptr;
+		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.
+	 */
+	if (!ja_node_ptr(node_flag)) {
+		dbg_printf("cds_ja_del: no node found for key %" PRIu64 "\n",
+				key);
+		return -ENOENT;
+	} else {
+		struct cds_hlist_head hlist_head;
+		struct cds_hlist_node *hlist_node;
+		struct cds_ja_node *entry, *match = NULL;
+		int count = 0;
+
+		hlist_head.next =
+			(struct cds_hlist_node *) ja_node_ptr(node_flag);
+		cds_hlist_for_each_entry_rcu(entry,
+				hlist_node,
+				&hlist_head,
+				list) {
+			dbg_printf("cds_ja_del: compare %p with entry %p\n", node, entry);
+			if (entry == node)
+				match = entry;
+			count++;
+		}
+		if (!match) {
+			dbg_printf("cds_ja_del: no node match for node %p key %" PRIu64 "\n", node, key);
+			return -ENOENT;
+		}
+		assert(count > 0);
+		if (count == 1) {
+			/*
+			 * Removing last of duplicates. Last snapshot
+			 * does not have a shadow node (external leafs).
+			 */
+			snapshot_ptr[nr_snapshot] = prev_node_flag_ptr;
+			snapshot[nr_snapshot++] = node_flag;
+			ret = ja_detach_node(ja, snapshot, snapshot_ptr,
+					snapshot_n, nr_snapshot, key, node);
+		} else {
+			ret = ja_unchain_node(ja, snapshot[nr_snapshot - 1],
+				node_flag_ptr, node_flag, match);
+		}
+	}
+	/*
+	 * 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;
+}
+
 struct cds_ja *_cds_ja_new(unsigned int key_bits,
 		const struct rcu_flavor_struct *flavor)
 {
@@ -1015,13 +1841,13 @@ struct cds_ja *_cds_ja_new(unsigned int key_bits,
 
 	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;
@@ -1042,13 +1868,13 @@ struct cds_ja *_cds_ja_new(unsigned int key_bits,
 	 * Note: we should not free this node until judy array destroy.
 	 */
 	root_shadow_node = rcuja_shadow_set(ja->ht,
-			ja_node_ptr((struct cds_ja_inode_flag *) &ja->root),
-			NULL);
+			(struct cds_ja_inode_flag *) &ja->root,
+			NULL, ja);
 	if (!root_shadow_node) {
 		ret = -ENOMEM;
 		goto ht_node_error;
 	}
-	root_shadow_node->is_root = 1;
+	root_shadow_node->level = 0;
 
 	return ja;
 
@@ -1062,16 +1888,119 @@ ja_error:
 	return NULL;
 }
 
+/*
+ * Called from RCU read-side CS.
+ */
+__attribute__((visibility("protected")))
+void rcuja_free_all_children(struct cds_ja_shadow_node *shadow_node,
+		struct cds_ja_inode_flag *node_flag,
+		void (*free_node_cb)(struct rcu_head *head))
+{
+	const struct rcu_flavor_struct *flavor;
+	unsigned int type_index;
+	struct cds_ja_inode *node;
+	const struct cds_ja_type *type;
+
+	flavor = cds_lfht_rcu_flavor(shadow_node->ja->ht);
+	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:
+	{
+		uint8_t nr_child =
+			ja_linear_node_get_nr_child(type, node);
+		unsigned int i;
+
+		for (i = 0; i < nr_child; i++) {
+			struct cds_ja_inode_flag *iter;
+			struct cds_hlist_head head;
+			struct cds_ja_node *entry;
+			struct cds_hlist_node *pos;
+			uint8_t v;
+
+			ja_linear_node_get_ith_pos(type, node, i, &v, &iter);
+			if (!iter)
+				continue;
+			head.next = (struct cds_hlist_node *) iter;
+			cds_hlist_for_each_entry_rcu(entry, pos, &head, list) {
+				flavor->update_call_rcu(&entry->head, free_node_cb);
+			}
+		}
+		break;
+	}
+	case RCU_JA_POOL:
+	{
+		unsigned int pool_nr;
+
+		for (pool_nr = 0; pool_nr < (1U << type->nr_pool_order); pool_nr++) {
+			struct cds_ja_inode *pool =
+				ja_pool_node_get_ith_pool(type, node, pool_nr);
+			uint8_t nr_child =
+				ja_linear_node_get_nr_child(type, pool);
+			unsigned int j;
+
+			for (j = 0; j < nr_child; j++) {
+				struct cds_ja_inode_flag *iter;
+				struct cds_hlist_head head;
+				struct cds_ja_node *entry;
+				struct cds_hlist_node *pos;
+				uint8_t v;
+
+				ja_linear_node_get_ith_pos(type, node, j, &v, &iter);
+				if (!iter)
+					continue;
+				head.next = (struct cds_hlist_node *) iter;
+				cds_hlist_for_each_entry_rcu(entry, pos, &head, list) {
+					flavor->update_call_rcu(&entry->head, free_node_cb);
+				}
+			}
+		}
+		break;
+	}
+	case RCU_JA_NULL:
+		break;
+	case RCU_JA_PIGEON:
+	{
+		uint8_t nr_child;
+		unsigned int i;
+
+		nr_child = shadow_node->nr_child;
+		for (i = 0; i < nr_child; i++) {
+			struct cds_ja_inode_flag *iter;
+			struct cds_hlist_head head;
+			struct cds_ja_node *entry;
+			struct cds_hlist_node *pos;
+
+			iter = ja_pigeon_node_get_ith_pos(type, node, i);
+			if (!iter)
+				continue;
+			head.next = (struct cds_hlist_node *) iter;
+			cds_hlist_for_each_entry_rcu(entry, pos, &head, list) {
+				flavor->update_call_rcu(&entry->head, free_node_cb);
+			}
+		}
+		break;
+	}
+	default:
+		assert(0);
+	}
+}
+
 /*
  * There should be no more concurrent add to the judy array while it is
  * being destroyed (ensured by the caller).
  */
-int cds_ja_destroy(struct cds_ja *ja)
+int cds_ja_destroy(struct cds_ja *ja,
+		void (*free_node_cb)(struct rcu_head *head))
 {
 	int ret;
 
 	rcuja_shadow_prune(ja->ht,
-		RCUJA_SHADOW_CLEAR_FREE_NODE | RCUJA_SHADOW_CLEAR_FREE_LOCK);
+		RCUJA_SHADOW_CLEAR_FREE_NODE | RCUJA_SHADOW_CLEAR_FREE_LOCK,
+		free_node_cb);
 	ret = rcuja_delete_ht(ja->ht);
 	if (ret)
 		return ret;