include/linux/rculist.h - kernel/msm - Gitiles

 #ifndef _LINUX_RCULIST_H
 #define _LINUX_RCULIST_H

 #ifdef __KERNEL__

 /*
  * RCU-protected list version
  */
 #include <linux/list.h>
 #include <linux/rcupdate.h>

 /*
  * Why is there no list_empty_rcu()?  Because list_empty() serves this
  * purpose.  The list_empty() function fetches the RCU-protected pointer
  * and compares it to the address of the list head, but neither dereferences
  * this pointer itself nor provides this pointer to the caller.  Therefore,
  * it is not necessary to use rcu_dereference(), so that list_empty() can
  * be used anywhere you would want to use a list_empty_rcu().
  */

 /*
  * return the ->next pointer of a list_head in an rcu safe
  * way, we must not access it directly
  */
 #define list_next_rcu(list)	(*((struct list_head __rcu **)(&(list)->next)))

 /*
  * 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(list_next_rcu(prev), 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(list_next_rcu(new->prev), 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(list_next_rcu(head), first);
 	first->prev = head;
 	at->prev = last;
 }

 /**
  * list_entry_rcu - get the struct for this entry
  * @ptr:        the &struct list_head pointer.
  * @type:       the type of the struct this is embedded in.
  * @member:     the name of the list_struct within the struct.
  *
  * This primitive may safely run concurrently with the _rcu list-mutation
  * primitives such as list_add_rcu() as long as it's guarded by rcu_read_lock().
  */
 #define list_entry_rcu(ptr, type, member) \
 	({typeof (*ptr) __rcu *__ptr = (typeof (*ptr) __rcu __force *)ptr; \
 	 container_of((typeof(ptr))rcu_dereference_raw(__ptr), type, member); \
 	})

 /**
  * list_first_entry_rcu - get the first element from a list
  * @ptr:        the list head to take the element from.
  * @type:       the type of the struct this is embedded in.
  * @member:     the name of the list_struct within the struct.
  *
  * Note, that list is expected to be not empty.
  *
  * This primitive may safely run concurrently with the _rcu list-mutation
  * primitives such as list_add_rcu() as long as it's guarded by rcu_read_lock().
  */
 #define list_first_entry_rcu(ptr, type, member) \
 	list_entry_rcu((ptr)->next, type, member)

 /**
  * 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((head)->next, typeof(*pos), member); \
 		&pos->member != (head); \
 		pos = list_entry_rcu(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_raw(list_next_rcu(pos)); \
 		(pos) != (head); \
 		(pos) = rcu_dereference_raw(list_next_rcu(pos)))

 /**
  * list_for_each_entry_continue_rcu - continue iteration over 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.
  *
  * Continue to iterate over list of given type, continuing after
  * the current position.
  */
 #define list_for_each_entry_continue_rcu(pos, head, member) 		\
 	for (pos = list_entry_rcu(pos->member.next, typeof(*pos), member); \
 	     &pos->member != (head);	\
 	     pos = list_entry_rcu(pos->member.next, typeof(*pos), member))

 /**
  * 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(*(struct hlist_node __rcu **)new->pprev, new);
 	if (next)
 		new->next->pprev = &new->next;
 	old->pprev = LIST_POISON2;
 }

 /*
  * return the first or the next element in an RCU protected hlist
  */
 #define hlist_first_rcu(head)	(*((struct hlist_node __rcu **)(&(head)->first)))
 #define hlist_next_rcu(node)	(*((struct hlist_node __rcu **)(&(node)->next)))
 #define hlist_pprev_rcu(node)	(*((struct hlist_node __rcu **)((node)->pprev)))

 /**
  * 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(hlist_first_rcu(h), 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(hlist_pprev_rcu(n), 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(hlist_next_rcu(prev), n);
 	if (n->next)
 		n->next->pprev = &n->next;
 }

 #define __hlist_for_each_rcu(pos, head)				\
 	for (pos = rcu_dereference(hlist_first_rcu(head));	\
 	     pos;						\
 	     pos = rcu_dereference(hlist_next_rcu(pos)))

 /**
  * 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_raw(hlist_first_rcu(head));		\
 		pos &&							 \
 		({ tpos = hlist_entry(pos, typeof(*tpos), member); 1; }); \
 		pos = rcu_dereference_raw(hlist_next_rcu(pos)))

 /**
  * hlist_for_each_entry_rcu_bh - 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_bh(tpos, pos, head, member)		 \
 	for (pos = rcu_dereference_bh((head)->first);			 \
 		pos &&							 \
 		({ tpos = hlist_entry(pos, typeof(*tpos), member); 1; }); \
 		pos = rcu_dereference_bh(pos->next))

 /**
  * hlist_for_each_entry_continue_rcu - iterate over a hlist continuing after current point
  * @tpos:	the type * to use as a loop cursor.
  * @pos:	the &struct hlist_node to use as a loop cursor.
  * @member:	the name of the hlist_node within the struct.
  */
 #define hlist_for_each_entry_continue_rcu(tpos, pos, member)		\
 	for (pos = rcu_dereference((pos)->next);			\
 	     pos &&							\
 	     ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1; });  \
 	     pos = rcu_dereference(pos->next))

 /**
  * hlist_for_each_entry_continue_rcu_bh - iterate over a hlist continuing after current point
  * @tpos:	the type * to use as a loop cursor.
  * @pos:	the &struct hlist_node to use as a loop cursor.
  * @member:	the name of the hlist_node within the struct.
  */
 #define hlist_for_each_entry_continue_rcu_bh(tpos, pos, member)		\
 	for (pos = rcu_dereference_bh((pos)->next);			\
 	     pos &&							\
 	     ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1; });  \
 	     pos = rcu_dereference_bh(pos->next))


 #endif	/* __KERNEL__ */
 #endif
	#ifndef _LINUX_RCULIST_H
	#define _LINUX_RCULIST_H

	#ifdef __KERNEL__

	/*
	* RCU-protected list version
	*/
	#include <linux/list.h>
	#include <linux/rcupdate.h>

	/*
	* Why is there no list_empty_rcu()? Because list_empty() serves this
	* purpose. The list_empty() function fetches the RCU-protected pointer
	* and compares it to the address of the list head, but neither dereferences
	* this pointer itself nor provides this pointer to the caller. Therefore,
	* it is not necessary to use rcu_dereference(), so that list_empty() can
	* be used anywhere you would want to use a list_empty_rcu().
	*/

	/*
	* return the ->next pointer of a list_head in an rcu safe
	* way, we must not access it directly
	*/
	#define list_next_rcu(list) (((struct list_head __rcu *)(&(list)->next)))

	/*
	* 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(list_next_rcu(prev), 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(list_next_rcu(new->prev), 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(list_next_rcu(head), first);
	first->prev = head;
	at->prev = last;
	}

	/**
	* list_entry_rcu - get the struct for this entry
	* @ptr: the &struct list_head pointer.
	* @type: the type of the struct this is embedded in.
	* @member: the name of the list_struct within the struct.
	*
	* This primitive may safely run concurrently with the _rcu list-mutation
	* primitives such as list_add_rcu() as long as it's guarded by rcu_read_lock().
	*/
	#define list_entry_rcu(ptr, type, member) \
	({typeof (ptr) __rcu __ptr = (typeof (ptr) __rcu __force )ptr; \
	container_of((typeof(ptr))rcu_dereference_raw(__ptr), type, member); \
	})

	/**
	* list_first_entry_rcu - get the first element from a list
	* @ptr: the list head to take the element from.
	* @type: the type of the struct this is embedded in.
	* @member: the name of the list_struct within the struct.
	*
	* Note, that list is expected to be not empty.
	*
	* This primitive may safely run concurrently with the _rcu list-mutation
	* primitives such as list_add_rcu() as long as it's guarded by rcu_read_lock().
	*/
	#define list_first_entry_rcu(ptr, type, member) \
	list_entry_rcu((ptr)->next, type, member)

	/**
	* 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((head)->next, typeof(*pos), member); \
	&pos->member != (head); \
	pos = list_entry_rcu(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_raw(list_next_rcu(pos)); \
	(pos) != (head); \
	(pos) = rcu_dereference_raw(list_next_rcu(pos)))

	/**
	* list_for_each_entry_continue_rcu - continue iteration over 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.
	*
	* Continue to iterate over list of given type, continuing after
	* the current position.
	*/
	#define list_for_each_entry_continue_rcu(pos, head, member) \
	for (pos = list_entry_rcu(pos->member.next, typeof(*pos), member); \
	&pos->member != (head); \
	pos = list_entry_rcu(pos->member.next, typeof(*pos), member))

	/**
	* 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((struct hlist_node __rcu *)new->pprev, new);
	if (next)
	new->next->pprev = &new->next;
	old->pprev = LIST_POISON2;
	}

	/*
	* return the first or the next element in an RCU protected hlist
	*/
	#define hlist_first_rcu(head) (((struct hlist_node __rcu *)(&(head)->first)))
	#define hlist_next_rcu(node) (((struct hlist_node __rcu *)(&(node)->next)))
	#define hlist_pprev_rcu(node) (((struct hlist_node __rcu *)((node)->pprev)))

	/**
	* 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(hlist_first_rcu(h), 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(hlist_pprev_rcu(n), 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(hlist_next_rcu(prev), n);
	if (n->next)
	n->next->pprev = &n->next;
	}

	#define __hlist_for_each_rcu(pos, head) \
	for (pos = rcu_dereference(hlist_first_rcu(head)); \
	pos; \
	pos = rcu_dereference(hlist_next_rcu(pos)))

	/**
	* 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_raw(hlist_first_rcu(head)); \
	pos && \
	({ tpos = hlist_entry(pos, typeof(*tpos), member); 1; }); \
	pos = rcu_dereference_raw(hlist_next_rcu(pos)))

	/**
	* hlist_for_each_entry_rcu_bh - 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_bh(tpos, pos, head, member) \
	for (pos = rcu_dereference_bh((head)->first); \
	pos && \
	({ tpos = hlist_entry(pos, typeof(*tpos), member); 1; }); \
	pos = rcu_dereference_bh(pos->next))

	/**
	* hlist_for_each_entry_continue_rcu - iterate over a hlist continuing after current point
	* @tpos: the type * to use as a loop cursor.
	* @pos: the &struct hlist_node to use as a loop cursor.
	* @member: the name of the hlist_node within the struct.
	*/
	#define hlist_for_each_entry_continue_rcu(tpos, pos, member) \
	for (pos = rcu_dereference((pos)->next); \
	pos && \
	({ tpos = hlist_entry(pos, typeof(*tpos), member); 1; }); \
	pos = rcu_dereference(pos->next))

	/**
	* hlist_for_each_entry_continue_rcu_bh - iterate over a hlist continuing after current point
	* @tpos: the type * to use as a loop cursor.
	* @pos: the &struct hlist_node to use as a loop cursor.
	* @member: the name of the hlist_node within the struct.
	*/
	#define hlist_for_each_entry_continue_rcu_bh(tpos, pos, member) \
	for (pos = rcu_dereference_bh((pos)->next); \
	pos && \
	({ tpos = hlist_entry(pos, typeof(*tpos), member); 1; }); \
	pos = rcu_dereference_bh(pos->next))


	#endif /* __KERNEL__ */
	#endif