#ifndef _LINUX_RCULIST_H

#define _LINUX_RCULIST_H

#ifdef __KERNEL__

/*

 * RCU-protected list version

 */

#include <linux/list.h>

#include <linux/rcupdate.h>

/*

 * Insert a new entry between two known consecutive entries.

 *

 * This is only for internal list manipulation where we know

 * the prev/next entries already!

 */

static inline void __list_add_rcu(struct list_head *new,

		struct list_head *prev, struct list_head *next)

{

	new->next = next;

	new->prev = prev;

	rcu_assign_pointer(prev->next, new);

	next->prev = new;

}

/**

 * list_add_rcu - add a new entry to rcu-protected list

 * @new: new entry to be added

 * @head: list head to add it after

 *

 * Insert a new entry after the specified head.

 * This is good for implementing stacks.

 *

 * The caller must take whatever precautions are necessary

 * (such as holding appropriate locks) to avoid racing

 * with another list-mutation primitive, such as list_add_rcu()

 * or list_del_rcu(), running on this same list.

 * However, it is perfectly legal to run concurrently with

 * the _rcu list-traversal primitives, such as

 * list_for_each_entry_rcu().

 */

static inline void list_add_rcu(struct list_head *new, struct list_head *head)

{

	__list_add_rcu(new, head, head->next);

}

/**

 * list_add_tail_rcu - add a new entry to rcu-protected list

 * @new: new entry to be added

 * @head: list head to add it before

 *

 * Insert a new entry before the specified head.

 * This is useful for implementing queues.

 *

 * The caller must take whatever precautions are necessary

 * (such as holding appropriate locks) to avoid racing

 * with another list-mutation primitive, such as list_add_tail_rcu()

 * or list_del_rcu(), running on this same list.

 * However, it is perfectly legal to run concurrently with

 * the _rcu list-traversal primitives, such as

 * list_for_each_entry_rcu().

 */

static inline void list_add_tail_rcu(struct list_head *new,

					struct list_head *head)

{

	__list_add_rcu(new, head->prev, head);

}

/**

 * list_del_rcu - deletes entry from list without re-initialization

 * @entry: the element to delete from the list.

 *

 * Note: list_empty() on entry does not return true after this,

 * the entry is in an undefined state. It is useful for RCU based

 * lockfree traversal.

 *

 * In particular, it means that we can not poison the forward

 * pointers that may still be used for walking the list.

 *

 * The caller must take whatever precautions are necessary

 * (such as holding appropriate locks) to avoid racing

 * with another list-mutation primitive, such as list_del_rcu()

 * or list_add_rcu(), running on this same list.

 * However, it is perfectly legal to run concurrently with

 * the _rcu list-traversal primitives, such as

 * list_for_each_entry_rcu().

 *

 * Note that the caller is not permitted to immediately free

 * the newly deleted entry.  Instead, either synchronize_rcu()

 * or call_rcu() must be used to defer freeing until an RCU

 * grace period has elapsed.

 */

static inline void list_del_rcu(struct list_head *entry)

{

	__list_del(entry->prev, entry->next);

	entry->prev = LIST_POISON2;

}

/**

 * hlist_del_init_rcu - deletes entry from hash list with re-initialization

 * @n: the element to delete from the hash list.

 *

 * Note: list_unhashed() on the node return true after this. It is

 * useful for RCU based read lockfree traversal if the writer side

 * must know if the list entry is still hashed or already unhashed.

 *

 * In particular, it means that we can not poison the forward pointers

 * that may still be used for walking the hash list and we can only

 * zero the pprev pointer so list_unhashed() will return true after

 * this.

 *

 * The caller must take whatever precautions are necessary (such as

 * holding appropriate locks) to avoid racing with another

 * list-mutation primitive, such as hlist_add_head_rcu() or

 * hlist_del_rcu(), running on this same list.  However, it is

 * perfectly legal to run concurrently with the _rcu list-traversal

 * primitives, such as hlist_for_each_entry_rcu().

 */

static inline void hlist_del_init_rcu(struct hlist_node *n)

{

	if (!hlist_unhashed(n)) {

		__hlist_del(n);

		n->pprev = NULL;

	}

}

/**

 * list_replace_rcu - replace old entry by new one

 * @old : the element to be replaced

 * @new : the new element to insert

 *

 * The @old entry will be replaced with the @new entry atomically.

 * Note: @old should not be empty.

 */

static inline void list_replace_rcu(struct list_head *old,

				struct list_head *new)

{

	new->next = old->next;

	new->prev = old->prev;

	rcu_assign_pointer(new->prev->next, new);

	new->next->prev = new;

	old->prev = LIST_POISON2;

}

/**

 * list_splice_init_rcu - splice an RCU-protected list into an existing list.

 * @list:	the RCU-protected list to splice

 * @head:	the place in the list to splice the first list into

 * @sync:	function to sync: synchronize_rcu(), synchronize_sched(), ...

 *

 * @head can be RCU-read traversed concurrently with this function.

 *

 * Note that this function blocks.

 *

 * Important note: the caller must take whatever action is necessary to

 *	prevent any other updates to @head.  In principle, it is possible

 *	to modify the list as soon as sync() begins execution.

 *	If this sort of thing becomes necessary, an alternative version

 *	based on call_rcu() could be created.  But only if -really-

 *	needed -- there is no shortage of RCU API members.

 */

static inline void list_splice_init_rcu(struct list_head *list,

					struct list_head *head,

					void (*sync)(void))

{

	struct list_head *first = list->next;

	struct list_head *last = list->prev;

	struct list_head *at = head->next;

	if (list_empty(head))

		return;

	/* "first" and "last" tracking list, so initialize it. */

	INIT_LIST_HEAD(list);

	/*

	 * At this point, the list body still points to the source list.

	 * Wait for any readers to finish using the list before splicing

	 * the list body into the new list.  Any new readers will see

	 * an empty list.

	 */

	sync();

	/*

	 * Readers are finished with the source list, so perform splice.

	 * The order is important if the new list is global and accessible

	 * to concurrent RCU readers.  Note that RCU readers are not

	 * permitted to traverse the prev pointers without excluding

	 * this function.

	 */

	last->next = at;

	rcu_assign_pointer(head->next, first);

	first->prev = head;

	at->prev = last;

}

#define __list_for_each_rcu(pos, head) \

	for (pos = rcu_dereference((head)->next); \

		pos != (head); \

		pos = rcu_dereference(pos->next))

/**

 * list_for_each_entry_rcu	-	iterate over rcu list of given type

 * @pos:	the type * to use as a loop cursor.

 * @head:	the head for your list.

 * @member:	the name of the list_struct within the struct.

 *

 * This list-traversal primitive may safely run concurrently with

 * the _rcu list-mutation primitives such as list_add_rcu()

 * as long as the traversal is guarded by rcu_read_lock().

 */

#define list_for_each_entry_rcu(pos, head, member) \

	for (pos = list_entry(rcu_dereference((head)->next), typeof(*pos), member); \

		prefetch(pos->member.next), &pos->member != (head); \

		pos = list_entry(rcu_dereference(pos->member.next), typeof(*pos), member))

/**

 * list_for_each_continue_rcu

 * @pos:	the &struct list_head to use as a loop cursor.

 * @head:	the head for your list.

 *

 * Iterate over an rcu-protected list, continuing after current point.

 *

 * This list-traversal primitive may safely run concurrently with

 * the _rcu list-mutation primitives such as list_add_rcu()

 * as long as the traversal is guarded by rcu_read_lock().

 */

#define list_for_each_continue_rcu(pos, head) \

	for ((pos) = rcu_dereference((pos)->next); \

		prefetch((pos)->next), (pos) != (head); \

		(pos) = rcu_dereference((pos)->next))

/**

 * hlist_del_rcu - deletes entry from hash list without re-initialization

 * @n: the element to delete from the hash list.

 *

 * Note: list_unhashed() on entry does not return true after this,

 * the entry is in an undefined state. It is useful for RCU based

 * lockfree traversal.

 *

 * In particular, it means that we can not poison the forward

 * pointers that may still be used for walking the hash list.

 *

 * The caller must take whatever precautions are necessary

 * (such as holding appropriate locks) to avoid racing

 * with another list-mutation primitive, such as hlist_add_head_rcu()

 * or hlist_del_rcu(), running on this same list.

 * However, it is perfectly legal to run concurrently with

 * the _rcu list-traversal primitives, such as

 * hlist_for_each_entry().

 */

static inline void hlist_del_rcu(struct hlist_node *n)

{

	__hlist_del(n);

	n->pprev = LIST_POISON2;

}

/**

 * hlist_replace_rcu - replace old entry by new one

 * @old : the element to be replaced

 * @new : the new element to insert

 *

 * The @old entry will be replaced with the @new entry atomically.

 */

static inline void hlist_replace_rcu(struct hlist_node *old,

					struct hlist_node *new)

{

	struct hlist_node *next = old->next;

	new->next = next;

	new->pprev = old->pprev;

	rcu_assign_pointer(*new->pprev, new);

	if (next)

		new->next->pprev = &new->next;

	old->pprev = LIST_POISON2;

}

/**

 * hlist_add_head_rcu

 * @n: the element to add to the hash list.

 * @h: the list to add to.

 *

 * Description:

 * Adds the specified element to the specified hlist,

 * while permitting racing traversals.

 *

 * The caller must take whatever precautions are necessary

 * (such as holding appropriate locks) to avoid racing

 * with another list-mutation primitive, such as hlist_add_head_rcu()

 * or hlist_del_rcu(), running on this same list.

 * However, it is perfectly legal to run concurrently with

 * the _rcu list-traversal primitives, such as

 * hlist_for_each_entry_rcu(), used to prevent memory-consistency

 * problems on Alpha CPUs.  Regardless of the type of CPU, the

 * list-traversal primitive must be guarded by rcu_read_lock().

 */

static inline void hlist_add_head_rcu(struct hlist_node *n,

					struct hlist_head *h)

{

	struct hlist_node *first = h->first;

	n->next = first;

	n->pprev = &h->first;

	rcu_assign_pointer(h->first, n);

	if (first)

		first->pprev = &n->next;

}

/**

 * hlist_add_before_rcu

 * @n: the new element to add to the hash list.

 * @next: the existing element to add the new element before.

 *

 * Description:

 * Adds the specified element to the specified hlist

 * before the specified node while permitting racing traversals.

 *

 * The caller must take whatever precautions are necessary

 * (such as holding appropriate locks) to avoid racing

 * with another list-mutation primitive, such as hlist_add_head_rcu()

 * or hlist_del_rcu(), running on this same list.

 * However, it is perfectly legal to run concurrently with

 * the _rcu list-traversal primitives, such as

 * hlist_for_each_entry_rcu(), used to prevent memory-consistency

 * problems on Alpha CPUs.

 */

static inline void hlist_add_before_rcu(struct hlist_node *n,

					struct hlist_node *next)

{

	n->pprev = next->pprev;

	n->next = next;

	rcu_assign_pointer(*(n->pprev), n);

	next->pprev = &n->next;

}

/**

 * hlist_add_after_rcu

 * @prev: the existing element to add the new element after.

 * @n: the new element to add to the hash list.

 *

 * Description:

 * Adds the specified element to the specified hlist

 * after the specified node while permitting racing traversals.

 *

 * The caller must take whatever precautions are necessary

 * (such as holding appropriate locks) to avoid racing

 * with another list-mutation primitive, such as hlist_add_head_rcu()

 * or hlist_del_rcu(), running on this same list.

 * However, it is perfectly legal to run concurrently with

 * the _rcu list-traversal primitives, such as

 * hlist_for_each_entry_rcu(), used to prevent memory-consistency

 * problems on Alpha CPUs.

 */

static inline void hlist_add_after_rcu(struct hlist_node *prev,

				       struct hlist_node *n)

{

	n->next = prev->next;

	n->pprev = &prev->next;

	rcu_assign_pointer(prev->next, n);

	if (n->next)

		n->next->pprev = &n->next;

}

/**

 * hlist_for_each_entry_rcu - iterate over rcu list of given type

 * @tpos:	the type * to use as a loop cursor.

 * @pos:	the &struct hlist_node to use as a loop cursor.

 * @head:	the head for your list.

 * @member:	the name of the hlist_node within the struct.

 *

 * This list-traversal primitive may safely run concurrently with

 * the _rcu list-mutation primitives such as hlist_add_head_rcu()

 * as long as the traversal is guarded by rcu_read_lock().

 */

#define hlist_for_each_entry_rcu(tpos, pos, head, member)		 \

	for (pos = rcu_dereference((head)->first);			 \

		pos && ({ prefetch(pos->next); 1; }) &&			 \

		({ tpos = hlist_entry(pos, typeof(*tpos), member); 1; }); \

		pos = rcu_dereference(pos->next))

#endif	/* __KERNEL__ */

#endif