X-Git-Url: http://git.liburcu.org/?a=blobdiff_plain;f=rcuja%2Frcuja.c;h=97381437368d295380de5230bc9c72ed9217a9ca;hb=b306a0fe21a4bde8ce65d35bbf4a836bdb72be68;hp=adb7b493524559fe8238f674b08858508dda1c2d;hpb=be9a7474cac017c7d0bed96efdb86e50ed0f6376;p=userspace-rcu.git

diff --git a/rcuja/rcuja.c b/rcuja/rcuja.c
index adb7b49..9738143 100644
--- a/rcuja/rcuja.c
+++ b/rcuja/rcuja.c
@@ -29,6 +29,8 @@
 #include <urcu/arch.h>
 #include <assert.h>
 #include <urcu-pointer.h>
+#include <urcu/uatomic.h>
+#include <stdint.h>
 
 #include "rcuja-internal.h"
 #include "bitfield.h"
@@ -59,23 +61,6 @@ 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	(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
-
-/*
- * Entry for NULL node is at index 8 of the table. It is never encoded
- * in flags.
- */
-#define NODE_INDEX_NULL		8
-
 /*
  * Iteration on the array to find the right node size for the number of
  * children stops when it reaches .max_child == 256 (this is the largest
@@ -214,7 +199,7 @@ void static_array_size_check(void)
 	struct {										\
 		uint8_t nr_child;								\
 		uint8_t child_value[ja_type_## index ##_max_linear_child];			\
-		struct cds_ja_node_flag *child_ptr[ja_type_## index ##_max_linear_child];	\
+		struct cds_ja_inode_flag *child_ptr[ja_type_## index ##_max_linear_child];	\
 	}
 
 #define DECLARE_POOL_NODE(index)								\
@@ -222,11 +207,11 @@ void static_array_size_check(void)
 		struct {									\
 			uint8_t nr_child;							\
 			uint8_t child_value[ja_type_## index ##_max_linear_child];		\
-			struct cds_ja_node_flag *child_ptr[ja_type_## index ##_max_linear_child]; \
+			struct cds_ja_inode_flag *child_ptr[ja_type_## index ##_max_linear_child]; \
 		} linear[1U << ja_type_## index ##_nr_pool_order];				\
 	}
 
-struct cds_ja_node {
+struct cds_ja_inode {
 	union {
 		/* Linear configuration */
 		DECLARE_LINEAR_NODE(0) conf_0;
@@ -241,46 +226,25 @@ struct cds_ja_node {
 
 		/* Pigeon configuration */
 		struct {
-			struct cds_ja_node_flag *child[ja_type_7_max_child];
+			struct cds_ja_inode_flag *child[ja_type_7_max_child];
 		} conf_7;
 		/* data aliasing nodes for computed accesses */
-		uint8_t data[sizeof(struct cds_ja_node_flag *) * ja_type_7_max_child];
+		uint8_t data[sizeof(struct cds_ja_inode_flag *) * ja_type_7_max_child];
 	} u;
 };
 
-static
-struct cds_ja_node_flag *ja_node_flag(struct cds_ja_node *node,
-		unsigned int type)
-{
-	assert(type < RCU_JA_NR_TYPES);
-	return (struct cds_ja_node_flag *) (((unsigned long) node) | type);
-}
-
-static
-struct cds_ja_node *ja_node_ptr(struct cds_ja_node_flag *node)
-{
-	return (struct cds_ja_node *) (((unsigned long) node) | JA_PTR_MASK);
-}
-
-static
-unsigned int ja_node_type(struct cds_ja_node_flag *node)
-{
-	unsigned int type;
-
-	if (ja_node_ptr(node) == NULL) {
-		return NODE_INDEX_NULL;
-	}
-	type = (unsigned int) ((unsigned long) node & JA_TYPE_MASK);
-	assert(type < RCU_JA_NR_TYPES);
-	return type;
-}
+enum ja_recompact {
+	JA_RECOMPACT,
+	JA_RECOMPACT_ADD,
+	JA_RECOMPACT_DEL,
+};
 
-struct cds_ja_node *alloc_cds_ja_node(const struct cds_ja_type *ja_type)
+struct cds_ja_inode *alloc_cds_ja_node(const struct cds_ja_type *ja_type)
 {
 	return calloc(1U << ja_type->order, sizeof(char));
 }
 
-void free_cds_ja_node(struct cds_ja_node *node)
+void free_cds_ja_node(struct cds_ja_inode *node)
 {
 	free(node);
 }
@@ -298,10 +262,10 @@ uint8_t *align_ptr_size(uint8_t *ptr)
 
 static
 uint8_t ja_linear_node_get_nr_child(const struct cds_ja_type *type,
-		struct cds_ja_node *node)
+		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]);
 }
 
 /*
@@ -310,14 +274,15 @@ uint8_t ja_linear_node_get_nr_child(const struct cds_ja_type *type,
  * associated pointers is still NULL, we return NULL too.
  */
 static
-struct cds_ja_node_flag *ja_linear_node_get_nth(const struct cds_ja_type *type,
-		struct cds_ja_node *node,
+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,
 		uint8_t n)
 {
 	uint8_t nr_child;
 	uint8_t *values;
-	struct cds_ja_node_flag **pointers;
-	struct cds_ja_node_flag *ptr;
+	struct cds_ja_inode_flag **pointers;
+	struct cds_ja_inode_flag *ptr;
 	unsigned int i;
 
 	assert(type->type_class == RCU_JA_LINEAR || type->type_class == RCU_JA_POOL);
@@ -334,65 +299,83 @@ struct cds_ja_node_flag *ja_linear_node_get_nth(const struct cds_ja_type *type,
 	}
 	if (i >= nr_child)
 		return NULL;
-	pointers = (struct cds_ja_node_flag **) align_ptr_size(&values[type->max_linear_child]);
+	pointers = (struct cds_ja_inode_flag **) align_ptr_size(&values[type->max_linear_child]);
 	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];
 	return ptr;
 }
 
 static
-struct cds_ja_node_flag *ja_linear_node_get_ith_pos(const struct cds_ja_type *type,
-		struct cds_ja_node *node,
+void ja_linear_node_get_ith_pos(const struct cds_ja_type *type,
+		struct cds_ja_inode *node,
 		uint8_t i,
 		uint8_t *v,
-		struct cds_ja_node_flag **iter)
+		struct cds_ja_inode_flag **iter)
 {
 	uint8_t *values;
-	struct cds_ja_node_flag **pointers;
+	struct cds_ja_inode_flag **pointers;
 
 	assert(type->type_class == RCU_JA_LINEAR || type->type_class == RCU_JA_POOL);
 	assert(i < ja_linear_node_get_nr_child(type, node));
 
 	values = &node->u.data[1];
 	*v = values[i];
-	pointers = (struct cds_ja_node_flag **) align_ptr_size(&values[type->max_linear_child]);
+	pointers = (struct cds_ja_inode_flag **) align_ptr_size(&values[type->max_linear_child]);
 	*iter = pointers[i];
 }
 
 static
-struct cds_ja_node_flag *ja_pool_node_get_nth(const struct cds_ja_type *type,
-		struct cds_ja_node *node,
+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 ***child_node_flag_ptr,
 		uint8_t n)
 {
-	struct cds_ja_node *linear;
+	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_node *)
+	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, n);
+	return ja_linear_node_get_nth(type, linear, child_node_flag_ptr, n);
 }
 
 static
-struct cds_ja_node *ja_pool_node_get_ith_pool(const struct cds_ja_type *type,
-		struct cds_ja_node *node,
+struct cds_ja_inode *ja_pool_node_get_ith_pool(const struct cds_ja_type *type,
+		struct cds_ja_inode *node,
 		uint8_t i)
 {
 	assert(type->type_class == RCU_JA_POOL);
-	return (struct cds_ja_node *)
+	return (struct cds_ja_inode *)
 		&node->u.data[(unsigned int) i << type->pool_size_order];
 }
 
 static
-struct cds_ja_node_flag *ja_pigeon_node_get_nth(const struct cds_ja_type *type,
-		struct cds_ja_node *node,
+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,
 		uint8_t n)
 {
+	struct cds_ja_inode_flag **child_node_flag;
+
 	assert(type->type_class == RCU_JA_PIGEON);
-	return rcu_dereference(((struct cds_ja_node_flag **) node->u.data)[n]);
+	child_node_flag = &((struct cds_ja_inode_flag **) node->u.data)[n];
+	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)
+		*child_node_flag_ptr = child_node_flag;
+	return rcu_dereference(*child_node_flag);
+}
+
+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, i);
 }
 
 /*
@@ -400,11 +383,12 @@ struct cds_ja_node_flag *ja_pigeon_node_get_nth(const struct cds_ja_type *type,
  * node_flag is already rcu_dereference'd.
  */
 static
-struct cds_ja_node_flag *ja_node_get_nth(struct cds_ja_node_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,
 		uint8_t n)
 {
 	unsigned int type_index;
-	struct cds_ja_node *node;
+	struct cds_ja_inode *node;
 	const struct cds_ja_type *type;
 
 	node = ja_node_ptr(node_flag);
@@ -414,78 +398,89 @@ struct cds_ja_node_flag *ja_node_get_nth(struct cds_ja_node_flag *node_flag,
 
 	switch (type->type_class) {
 	case RCU_JA_LINEAR:
-		return ja_linear_node_get_nth(type, node, n);
+		return ja_linear_node_get_nth(type, node,
+				child_node_flag_ptr, n);
 	case RCU_JA_POOL:
-		return ja_pool_node_get_nth(type, node, n);
+		return ja_pool_node_get_nth(type, node,
+				child_node_flag_ptr, n);
 	case RCU_JA_PIGEON:
-		return ja_pigeon_node_get_nth(type, node, n);
+		return ja_pigeon_node_get_nth(type, node,
+				child_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_node *node,
+		struct cds_ja_inode *node,
 		struct cds_ja_shadow_node *shadow_node,
 		uint8_t n,
-		struct cds_ja_node_flag *child_node_flag)
+		struct cds_ja_inode_flag *child_node_flag)
 {
 	uint8_t nr_child;
 	uint8_t *values, *nr_child_ptr;
-	struct cds_ja_node_flag **pointers;
-	unsigned int i;
+	struct cds_ja_inode_flag **pointers;
+	unsigned int i, unused = 0;
 
 	assert(type->type_class == RCU_JA_LINEAR || type->type_class == RCU_JA_POOL);
 
 	nr_child_ptr = &node->u.data[0];
+	dbg_printf("linear set nth: nr_child_ptr %p\n", nr_child_ptr);
 	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];
+	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_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);
 	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),
+		(unsigned int) shadow_node->nr_child,
+		node, shadow_node);
+
 	return 0;
 }
 
 static
 int ja_pool_node_set_nth(const struct cds_ja_type *type,
-		struct cds_ja_node *node,
+		struct cds_ja_inode *node,
 		struct cds_ja_shadow_node *shadow_node,
 		uint8_t n,
-		struct cds_ja_node_flag *child_node_flag)
+		struct cds_ja_inode_flag *child_node_flag)
 {
-	struct cds_ja_node *linear;
+	struct cds_ja_inode *linear;
 
 	assert(type->type_class == RCU_JA_POOL);
-	linear = (struct cds_ja_node *)
+	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_set_nth(type, linear, shadow_node,
 			n, child_node_flag);
@@ -493,16 +488,16 @@ int ja_pool_node_set_nth(const struct cds_ja_type *type,
 
 static
 int ja_pigeon_node_set_nth(const struct cds_ja_type *type,
-		struct cds_ja_node *node,
+		struct cds_ja_inode *node,
 		struct cds_ja_shadow_node *shadow_node,
 		uint8_t n,
-		struct cds_ja_node_flag *child_node_flag)
+		struct cds_ja_inode_flag *child_node_flag)
 {
-	struct cds_ja_node_flag **ptr;
+	struct cds_ja_inode_flag **ptr;
 
 	assert(type->type_class == RCU_JA_PIGEON);
-	ptr = &((struct cds_ja_node_flag **) node->u.data)[n];
-	if (*ptr != NULL)
+	ptr = &((struct cds_ja_inode_flag **) node->u.data)[n];
+	if (*ptr)
 		return -EEXIST;
 	rcu_assign_pointer(*ptr, child_node_flag);
 	shadow_node->nr_child++;
@@ -512,14 +507,13 @@ 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_node *node,
+		struct cds_ja_inode *node,
 		struct cds_ja_shadow_node *shadow_node,
 		uint8_t n,
-		struct cds_ja_node_flag *child_node_flag)
+		struct cds_ja_inode_flag *child_node_flag)
 {
 	switch (type->type_class) {
 	case RCU_JA_LINEAR:
@@ -541,52 +535,181 @@ 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;
+}
+
 /*
  * 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, -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_node *old_node,
-		struct cds_ja_shadow_node **shadow_node,
-		struct cds_ja_node_flag **old_node_flag, uint8_t n,
-		struct cds_ja_node_flag *child_node_flag)
+		struct cds_ja_inode *old_node,
+		struct cds_ja_shadow_node *shadow_node,
+		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_node *new_node;
+	struct cds_ja_inode *new_node;
+	struct cds_ja_shadow_node *new_shadow_node = NULL;
 	const struct cds_ja_type *new_type;
-	struct cds_ja_node_flag *new_node_flag;
+	struct cds_ja_inode_flag *new_node_flag, *old_node_flag;
 	int ret;
+	int fallback = 0;
 
-	if (*shadow_node == NULL) {
-		new_type_index = 0;
-	} else {
-		new_type_index = old_type_index + 1;
-	}
-	new_type = &ja_types[new_type_index];
-	new_node = alloc_cds_ja_node(new_type);
-	if (!new_node)
-		return -ENOMEM;
-	new_node_flag = ja_node_flag(new_node, new_type_index);
+	old_node_flag = *old_node_flag_ptr;
 
-	ret = rcuja_shadow_set(ja->ht, new_node, *shadow_node);
-	if (ret)
-		return ret;
+	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);
+	}
 
-	if (*shadow_node == NULL) {
-		*shadow_node = rcuja_shadow_lookup_lock(ja->ht, new_node);
-		assert(*shadow_node);
+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];
+	if (new_type_index != NODE_INDEX_NULL) {
+		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_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;
 	}
 
-	/*
-	 * We need to clear nr_child, because it will be re-incremented
-	 * by _ja_node_set_nth().
-	 */
-	(*shadow_node)->nr_child = 0;
+	assert(mode != JA_RECOMPACT_ADD || old_type->type_class != RCU_JA_PIGEON);
+
+	if (new_type_index == NODE_INDEX_NULL)
+		goto skip_copy;
 
-	assert(old_type->type_class != RCU_JA_PIGEON);
 	switch (old_type->type_class) {
 	case RCU_JA_LINEAR:
 	{
@@ -595,14 +718,20 @@ int ja_node_recompact_add(struct cds_ja *ja,
 		unsigned int i;
 
 		for (i = 0; i < nr_child; i++) {
-			struct cds_ja_node_flag *iter;
+			struct cds_ja_inode_flag *iter;
 			uint8_t v;
 
 			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, *shadow_node,
+			if (mode == JA_RECOMPACT_DEL && *nullify_node_flag_ptr == iter)
+				continue;
+			ret = _ja_node_set_nth(new_type, new_node,
+					new_shadow_node,
 					v, iter);
+			if (new_type->type_class == RCU_JA_POOL && ret) {
+				goto fallback_toosmall;
+			}
 			assert(!ret);
 		}
 		break;
@@ -612,7 +741,7 @@ int ja_node_recompact_add(struct cds_ja *ja,
 		unsigned int pool_nr;
 
 		for (pool_nr = 0; pool_nr < (1U << old_type->nr_pool_order); pool_nr++) {
-			struct cds_ja_node *pool =
+			struct cds_ja_inode *pool =
 				ja_pool_node_get_ith_pool(old_type,
 					old_node, pool_nr);
 			uint8_t nr_child =
@@ -620,94 +749,879 @@ int ja_node_recompact_add(struct cds_ja *ja,
 			unsigned int j;
 
 			for (j = 0; j < nr_child; j++) {
-				struct cds_ja_node_flag *iter;
+				struct cds_ja_inode_flag *iter;
 				uint8_t v;
 
 				ja_linear_node_get_ith_pos(old_type, pool,
 						j, &v, &iter);
 				if (!iter)
 					continue;
-				ret = _ja_node_set_nth(new_type, new_node, *shadow_node,
+				if (mode == JA_RECOMPACT_DEL && *nullify_node_flag_ptr == iter)
+					continue;
+				ret = _ja_node_set_nth(new_type, new_node,
+						new_shadow_node,
 						v, iter);
+				if (new_type->type_class == RCU_JA_POOL
+						&& ret) {
+					goto fallback_toosmall;
+				}
 				assert(!ret);
 			}
 		}
 		break;
 	}
+	case RCU_JA_NULL:
+		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_shadow_node,
+					i, iter);
+			if (new_type->type_class == RCU_JA_POOL && ret) {
+				goto fallback_toosmall;
+			}
+			assert(!ret);
+		}
+		break;
+	}
 	default:
 		assert(0);
-		return -EINVAL;
+		ret = -EINVAL;
+		goto end;
+	}
+skip_copy:
+
+	if (mode == JA_RECOMPACT_ADD) {
+		/* 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 node through old_node_flag_ptr */
+	*old_node_flag_ptr = new_node_flag;
+	if (old_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);
 	}
 
-	/* add node */
-	ret = _ja_node_set_nth(new_type, new_node, *shadow_node,
-			n, child_node_flag);
-	assert(!ret);
-	/* Replace the old node with the new recompacted one */
-	rcu_assign_pointer(*old_node_flag, new_node_flag);
-	ret = rcuja_shadow_clear(ja->ht, old_node,
+	ret = 0;
+end:
+	return ret;
+
+fallback_toosmall:
+	/* fallback if next pool is too small */
+	assert(new_shadow_node);
+	ret = rcuja_shadow_clear(ja->ht, new_node_flag, new_shadow_node,
 			RCUJA_SHADOW_CLEAR_FREE_NODE);
 	assert(!ret);
-	return 0;
+
+	/* 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);
+	fallback = 1;
+	goto retry;
 }
 
+/*
+ * Return 0 on success, -EAGAIN if need to retry, or other negative
+ * error value otherwise.
+ */
 static
 int ja_node_set_nth(struct cds_ja *ja,
-		struct cds_ja_node_flag **node_flag, uint8_t n,
-		struct cds_ja_node_flag *child_node_flag)
+		struct cds_ja_inode_flag **node_flag, uint8_t n,
+		struct cds_ja_inode_flag *child_node_flag,
+		struct cds_ja_shadow_node *shadow_node)
 {
 	int ret;
 	unsigned int type_index;
 	const struct cds_ja_type *type;
-	struct cds_ja_node *node;
-	struct cds_ja_shadow_node *shadow_node = NULL;
+	struct cds_ja_inode *node;
+
+	dbg_printf("ja_node_set_nth for n=%u, node %p, shadow %p\n",
+		(unsigned int) n, ja_node_ptr(*node_flag), shadow_node);
 
 	node = ja_node_ptr(*node_flag);
 	type_index = ja_node_type(*node_flag);
 	type = &ja_types[type_index];
-	if (node != NULL) {
-		shadow_node = rcuja_shadow_lookup_lock(ja->ht, node);
-		assert(shadow_node);
-	}
 	ret = _ja_node_set_nth(type, node, shadow_node,
 			n, child_node_flag);
-	if (ret == -ENOSPC) {
+	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);
-		/* recompact always leave shadow_node locked */
+		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;
+}
+
+/*
+ * 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 head;
+	tree_depth = ja->tree_depth;
+	node_flag = rcu_dereference(ja->root);
+
+	/* level 0: root node */
+	if (!ja_node_ptr(node_flag))
+		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,
+			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 head;
+	}
+
+	/* Last level lookup succeded. We got an actual match. */
+	head.next = (struct cds_hlist_node *) node_flag;
+	return head;
+}
+
+/*
+ * We reached an unpopulated node. Create it and the children we need,
+ * and then attach the entire branch to the current node. This may
+ * trigger recompaction of the current node.  Locks needed: node lock
+ * (for add), and, possibly, parent node lock (to update pointer due to
+ * node recompaction).
+ *
+ * First take node lock, check if recompaction is needed, then take
+ * parent lock (if needed).  Then we can proceed to create the new
+ * branch. Publish the new branch, and release locks.
+ * TODO: we currently always take the parent lock even when not needed.
+ */
+static
+int ja_attach_node(struct cds_ja *ja,
+		struct cds_ja_inode_flag **node_flag_ptr,
+		struct cds_ja_inode_flag *node_flag,
+		struct cds_ja_inode_flag *parent_node_flag,
+		uint64_t key,
+		unsigned int level,
+		struct cds_ja_node *child_node)
+{
+	struct cds_ja_shadow_node *shadow_node = NULL,
+			*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;
+	struct cds_ja_inode_flag *iter_node_flag, *iter_dest_node_flag;
+	int ret, i;
+	struct cds_ja_inode_flag *created_nodes[JA_MAX_DEPTH];
+	int nr_created_nodes = 0;
+
+	dbg_printf("Attach node at level %u (node %p, node_flag %p)\n",
+		level, node, node_flag);
+
+	assert(node);
+	shadow_node = rcuja_shadow_lookup_lock(ja->ht, node_flag);
+	if (!shadow_node) {
+		ret = -EAGAIN;
+		goto end;
+	}
+	if (parent_node) {
+		parent_shadow_node = rcuja_shadow_lookup_lock(ja->ht,
+						parent_node_flag);
+		if (!parent_shadow_node) {
+			ret = -EAGAIN;
+			goto unlock_shadow;
+		}
 	}
+
+	if (*node_flag_ptr != NULL) {
+		/*
+		 * Attach point is non-NULL: it 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;
+
+	for (i = ja->tree_depth; i > (int) level; i--) {
+		uint8_t iter_key;
+
+		iter_key = (uint8_t) (key >> (JA_BITS_PER_BYTE * (ja->tree_depth - i)));
+		dbg_printf("branch creation level %d, key %u\n",
+				i - 1, (unsigned int) iter_key);
+		iter_dest_node_flag = NULL;
+		ret = ja_node_set_nth(ja, &iter_dest_node_flag,
+			iter_key,
+			iter_node_flag,
+			NULL);
+		if (ret)
+			goto check_error;
+		created_nodes[nr_created_nodes++] = iter_dest_node_flag;
+		iter_node_flag = iter_dest_node_flag;
+	}
+
+	if (level > 1) {
+		uint8_t iter_key;
+
+		iter_key = (uint8_t) (key >> (JA_BITS_PER_BYTE * (ja->tree_depth - level)));
+		/* We need to use set_nth on the previous level. */
+		iter_dest_node_flag = node_flag;
+		ret = ja_node_set_nth(ja, &iter_dest_node_flag,
+			iter_key,
+			iter_node_flag,
+			shadow_node);
+		if (ret)
+			goto check_error;
+		created_nodes[nr_created_nodes++] = iter_dest_node_flag;
+		iter_node_flag = iter_dest_node_flag;
+	}
+
+	/* 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);
+
+	/* Success */
+	ret = 0;
+
+check_error:
+	if (ret) {
+		for (i = 0; i < nr_created_nodes; i++) {
+			int tmpret;
+			int flags;
+
+			flags = RCUJA_SHADOW_CLEAR_FREE_LOCK;
+			if (i)
+				flags |= RCUJA_SHADOW_CLEAR_FREE_NODE;
+			tmpret = rcuja_shadow_clear(ja->ht,
+					created_nodes[i],
+					NULL,
+					flags);
+			assert(!tmpret);
+		}
+	}
+unlock_parent:
+	if (parent_shadow_node)
+		rcuja_shadow_unlock(parent_shadow_node);
+unlock_shadow:
+	if (shadow_node)
+		rcuja_shadow_unlock(shadow_node);
+end:
+	return ret;
+}
+
+/*
+ * 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_hlist_head *head,
+		struct cds_ja_node *node)
+{
+	struct cds_ja_shadow_node *shadow_node;
+
+	shadow_node = rcuja_shadow_lookup_lock(ja->ht, parent_node_flag);
+	if (!shadow_node) {
+		dbg_printf("AGAIN3\n");
+		return -EAGAIN;
+	}
+	cds_hlist_add_head_rcu(&node->list, head);
+	rcuja_shadow_unlock(shadow_node);
+	return 0;
+}
+
+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 *node_flag,
+		*parent_node_flag,
+		*parent2_node_flag;
+	int ret;
+
+	if (caa_unlikely(key > ja->key_max)) {
+		return -EINVAL;
+	}
+	tree_depth = ja->tree_depth;
+
+retry:
+	dbg_printf("cds_ja_add attempt: key %" PRIu64 ", node %p\n",
+		key, new_node);
+	parent2_node_flag = NULL;
+	parent_node_flag =
+		(struct cds_ja_inode_flag *) &ja->root;	/* Use root ptr address as key for mutex */
+	node_flag_ptr = &ja->root;
+	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);
+		if (!ja_node_ptr(node_flag)) {
+			ret = ja_attach_node(ja, node_flag_ptr,
+					parent_node_flag, parent2_node_flag,
+					key, i, new_node);
+			if (ret == -EAGAIN || ret == -EEXIST)
+				goto retry;
+			else
+				goto end;
+		}
+		iter_key = (uint8_t) (key >> (JA_BITS_PER_BYTE * (tree_depth - i - 1)));
+		parent2_node_flag = parent_node_flag;
+		parent_node_flag = node_flag;
+		node_flag = ja_node_get_nth(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);
+	}
+
+	/*
+	 * We reached bottom of tree, simply add node to last internal
+	 * 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,
+				parent2_node_flag, key, i, new_node);
+	} else {
+		ret = ja_chain_node(ja,
+			parent_node_flag,
+			(struct cds_hlist_head *) node_flag_ptr,
+			new_node);
+	}
+	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;
+		}
+		assert(shadow_node->nr_child > 0);
+		shadow_nodes[nr_shadow++] = shadow_node;
+		if (shadow_node->nr_child == 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;
+			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;
+			}
+			break;
+		}
+	}
+
+	/*
+	 * Check if node has been removed between RCU lookup and lock
+	 * acquisition.
+	 */
+	if (!*node_flag_ptr) {
+		ret = -ENOENT;
+		goto end;
+	}
+
+	/*
+	 * 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 as 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_hlist_head *head,
+		struct cds_ja_node *node)
+{
+	struct cds_ja_shadow_node *shadow_node;
+	struct cds_hlist_node *hlist_node;
+	int ret = 0, count = 0;
+
+	shadow_node = rcuja_shadow_lookup_lock(ja->ht, parent_node_flag);
+	if (!shadow_node)
+		return -EAGAIN;
+	/*
+	 * Retry if another thread removed all but one of duplicates
+	 * since check (that was performed without lock).
+	 */
+	cds_hlist_for_each_rcu(hlist_node, head, list) {
+		count++;
+	}
+
+	if (count == 1) {
+		ret = -EAGAIN;
+		goto end;
+	}
+	cds_hlist_del_rcu(&node->list);
+end:
 	rcuja_shadow_unlock(shadow_node);
 	return ret;
 }
 
-struct cds_ja *_cds_ja_new(const struct rcu_flavor_struct *flavor)
+/*
+ * 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;
+	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;
+
+	/* 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,
+			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],
+				&hlist_head, 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)
 {
 	struct cds_ja *ja;
+	int ret;
+	struct cds_ja_shadow_node *root_shadow_node;
 
 	ja = calloc(sizeof(*ja), 1);
 	if (!ja)
 		goto ja_error;
+
+	switch (key_bits) {
+	case 8:
+	case 16:
+	case 24:
+	case 32:
+	case 40:
+	case 48:
+	case 56:
+		ja->key_max = (1ULL << key_bits) - 1;
+		break;
+	case 64:
+		ja->key_max = UINT64_MAX;
+		break;
+	default:
+		goto check_error;
+	}
+
 	/* ja->root is NULL */
+	/* tree_depth 0 is for pointer to root node */
+	ja->tree_depth = (key_bits >> JA_LOG2_BITS_PER_BYTE) + 1;
+	assert(ja->tree_depth <= JA_MAX_DEPTH);
 	ja->ht = rcuja_create_ht(flavor);
 	if (!ja->ht)
 		goto ht_error;
+
+	/*
+	 * Note: we should not free this node until judy array destroy.
+	 */
+	root_shadow_node = rcuja_shadow_set(ja->ht,
+			(struct cds_ja_inode_flag *) &ja->root,
+			NULL, ja);
+	if (!root_shadow_node) {
+		ret = -ENOMEM;
+		goto ht_node_error;
+	}
+	root_shadow_node->level = 0;
+
 	return ja;
 
+ht_node_error:
+	ret = rcuja_delete_ht(ja->ht);
+	assert(!ret);
 ht_error:
+check_error:
 	free(ja);
 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);
-	return rcuja_delete_ht(ja->ht);
+		RCUJA_SHADOW_CLEAR_FREE_NODE | RCUJA_SHADOW_CLEAR_FREE_LOCK,
+		free_node_cb);
+	ret = rcuja_delete_ht(ja->ht);
+	if (ret)
+		return ret;
+	if (uatomic_read(&ja->nr_fallback))
+		fprintf(stderr,
+			"[warning] RCU Judy Array used %lu fallback node(s)\n",
+			uatomic_read(&ja->nr_fallback));
+	free(ja);
+	return 0;
 }