backport-include/linux/rculist.h

#ifndef __BACKPORT_RCULIST_H
#define __BACKPORT_RCULIST_H
#include_next <linux/rculist.h>
#include <linux/version.h>

#if LINUX_VERSION_IS_LESS(3,9,0)
#include <backport/magic.h>
#define hlist_for_each_entry_rcu4(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)))

#define hlist_for_each_entry_rcu3(pos, head, member)				\
	for (pos = hlist_entry_safe (rcu_dereference_raw(hlist_first_rcu(head)),\
			typeof(*(pos)), member);				\
		pos;								\
		pos = hlist_entry_safe(rcu_dereference_raw(hlist_next_rcu(	\
			&(pos)->member)), typeof(*(pos)), member))

#undef hlist_for_each_entry_rcu
#define hlist_for_each_entry_rcu(...) \
	macro_dispatcher(hlist_for_each_entry_rcu, __VA_ARGS__)(__VA_ARGS__)
#endif /* < 3.9 */

#ifndef list_for_each_entry_continue_rcu
#define list_for_each_entry_continue_rcu(pos, head, member) 		\
	for (pos = list_entry_rcu(pos->member.next, typeof(*pos), member); \
	     prefetch(pos->member.next), &pos->member != (head);	\
	     pos = list_entry_rcu(pos->member.next, typeof(*pos), member))
#endif

#ifndef list_entry_rcu
#define list_entry_rcu(ptr, type, member) \
	container_of(rcu_dereference(ptr), type, member)
#endif

#ifndef list_first_or_null_rcu
/**
 * list_first_or_null_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 if the list is empty, it returns NULL.
 *
 * 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_or_null_rcu(ptr, type, member) \
({ \
	struct list_head *__ptr = (ptr); \
	struct list_head *__next = ACCESS_ONCE(__ptr->next); \
	likely(__ptr != __next) ? list_entry_rcu(__next, type, member) : NULL; \
})
#endif /* list_first_or_null_rcu */


#if LINUX_VERSION_IS_LESS(5,4,0)

/**
 * 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_head within the struct.
 * @cond...:	optional lockdep expression if called from non-RCU protection.
 *
 * 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().
 */
#undef list_for_each_entry_rcu
#define list_for_each_entry_rcu(pos, head, member, cond...)		\
	for (pos = list_entry_rcu((head)->next, typeof(*pos), member); \
		&pos->member != (head); \
		pos = list_entry_rcu(pos->member.next, typeof(*pos), member))
#endif /* < 5.4 */

#endif /* __BACKPORT_RCULIST_H */