jack1/drivers/alsa_midi/list.h

/* -*- Mode: C ; c-basic-offset: 2 -*- */
/*****************************************************************************
*
*   Linux kernel header adapted for user-mode
*   The 2.6.17-rt1 version was used.
*
*   Original copyright holders of this code are unknown, they were not
*   mentioned in the original file.
*
*   This program is free software; you can redistribute it and/or modify
*   it under the terms of the GNU General Public License as published by
*   the Free Software Foundation; version 2 of the License
*
*   This program is distributed in the hope that it will be useful,
*   but WITHOUT ANY WARRANTY; without even the implied warranty of
*   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
*   GNU General Public License for more details.
*
*   You should have received a copy of the GNU General Public License
*   along with this program; if not, write to the Free Software
*   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
*****************************************************************************/

#ifndef _LINUX_LIST_H
#define _LINUX_LIST_H

#include <stddef.h>

#if !defined(offsetof)
#define offsetof(TYPE, MEMBER) ((size_t)&((TYPE*)0)->MEMBER)
#endif

/**
 * container_of - cast a member of a structure out to the containing structure
 * @ptr:	the pointer to the member.
 * @type:	the type of the container struct this is embedded in.
 * @member:	the name of the member within the struct.
 *
 */
#define container_of(ptr, type, member) ({			\
						 const typeof( ((type*)0)->member ) * __mptr = (ptr);	 \
						 (type*)( (char*)__mptr - offsetof (type, member) ); })

#define prefetch(x) (x = x)

/*
 * These are non-NULL pointers that will result in page faults
 * under normal circumstances, used to verify that nobody uses
 * non-initialized list entries.
 */
#define LIST_POISON1  ((void*)0x00100100)
#define LIST_POISON2  ((void*)0x00200200)

/*
 * Simple doubly linked list implementation.
 *
 * Some of the internal functions ("__xxx") are useful when
 * manipulating whole lists rather than single entries, as
 * sometimes we already know the next/prev entries and we can
 * generate better code by using them directly rather than
 * using the generic single-entry routines.
 */

struct list_head {
	struct list_head *next, *prev;
};

#define LIST_HEAD_INIT(name) { &(name), &(name) }

#define LIST_HEAD(name)	\
	struct list_head name = LIST_HEAD_INIT (name)

static inline void INIT_LIST_HEAD (struct list_head *list)
{
	list->next = list;
	list->prev = list;
}

/*
 * 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 (struct list_head *new,
			       struct list_head *prev,
			       struct list_head *next)
{
	next->prev = new;
	new->next = next;
	new->prev = prev;
	prev->next = new;
}

/**
 * list_add - add a new entry
 * @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.
 */
static inline void list_add (struct list_head *new, struct list_head *head)
{
	__list_add (new, head, head->next);
}

/**
 * list_add_tail - add a new entry
 * @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.
 */
static inline void list_add_tail (struct list_head *new, struct list_head *head)
{
	__list_add (new, head->prev, head);
}

/*
 * 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;
//  smp_wmb();
	next->prev = new;
	prev->next = 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);
}

/*
 * Delete a list entry by making the prev/next entries
 * point to each other.
 *
 * This is only for internal list manipulation where we know
 * the prev/next entries already!
 */
static inline void __list_del (struct list_head * prev, struct list_head * next)
{
	next->prev = prev;
	prev->next = next;
}

/**
 * list_del - deletes entry from list.
 * @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.
 */
static inline void list_del (struct list_head *entry)
{
	__list_del (entry->prev, entry->next);
	entry->next = LIST_POISON1;
	entry->prev = LIST_POISON2;
}

/**
 * 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;
}

/*
 * 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.
 */
static inline void list_replace_rcu (struct list_head *old,
				     struct list_head *new)
{
	new->next = old->next;
	new->prev = old->prev;
//  smp_wmb();
	new->next->prev = new;
	new->prev->next = new;
	old->prev = LIST_POISON2;
}

/**
 * list_del_init - deletes entry from list and reinitialize it.
 * @entry: the element to delete from the list.
 */
static inline void list_del_init (struct list_head *entry)
{
	__list_del (entry->prev, entry->next);
	INIT_LIST_HEAD (entry);
}

/**
 * list_move - delete from one list and add as another's head
 * @list: the entry to move
 * @head: the head that will precede our entry
 */
static inline void list_move (struct list_head *list, struct list_head *head)
{
	__list_del (list->prev, list->next);
	list_add (list, head);
}

/**
 * list_move_tail - delete from one list and add as another's tail
 * @list: the entry to move
 * @head: the head that will follow our entry
 */
static inline void list_move_tail (struct list_head *list,
				   struct list_head *head)
{
	__list_del (list->prev, list->next);
	list_add_tail (list, head);
}

/**
 * list_empty - tests whether a list is empty
 * @head: the list to test.
 */
static inline int list_empty (const struct list_head *head)
{
	return head->next == head;
}

/**
 * list_empty_careful - tests whether a list is
 * empty _and_ checks that no other CPU might be
 * in the process of still modifying either member
 *
 * NOTE: using list_empty_careful() without synchronization
 * can only be safe if the only activity that can happen
 * to the list entry is list_del_init(). Eg. it cannot be used
 * if another CPU could re-list_add() it.
 *
 * @head: the list to test.
 */
static inline int list_empty_careful (const struct list_head *head)
{
	struct list_head *next = head->next;

	return (next == head) && (next == head->prev);
}

static inline void __list_splice (struct list_head *list,
				  struct list_head *head)
{
	struct list_head *first = list->next;
	struct list_head *last = list->prev;
	struct list_head *at = head->next;

	first->prev = head;
	head->next = first;

	last->next = at;
	at->prev = last;
}

/**
 * list_splice - join two lists
 * @list: the new list to add.
 * @head: the place to add it in the first list.
 */
static inline void list_splice (struct list_head *list, struct list_head *head)
{
	if (!list_empty (list)) {
		__list_splice (list, head);
	}
}

/**
 * list_splice_init - join two lists and reinitialise the emptied list.
 * @list: the new list to add.
 * @head: the place to add it in the first list.
 *
 * The list at @list is reinitialised
 */
static inline void list_splice_init (struct list_head *list,
				     struct list_head *head)
{
	if (!list_empty (list)) {
		__list_splice (list, head);
		INIT_LIST_HEAD (list);
	}
}

/**
 * list_entry - 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.
 */
#define list_entry(ptr, type, member) \
	container_of (ptr, type, member)

/**
 * list_for_each  - iterate over a list
 * @pos:  the &struct list_head to use as a loop counter.
 * @head: the head for your list.
 */
#define list_for_each(pos, head) \
	for (pos = (head)->next; prefetch (pos->next), pos != (head); \
	     pos = pos->next)

/**
 * __list_for_each  - iterate over a list
 * @pos:  the &struct list_head to use as a loop counter.
 * @head: the head for your list.
 *
 * This variant differs from list_for_each() in that it's the
 * simplest possible list iteration code, no prefetching is done.
 * Use this for code that knows the list to be very short (empty
 * or 1 entry) most of the time.
 */
#define __list_for_each(pos, head) \
	for (pos = (head)->next; pos != (head); pos = pos->next)

/**
 * list_for_each_prev - iterate over a list backwards
 * @pos:  the &struct list_head to use as a loop counter.
 * @head: the head for your list.
 */
#define list_for_each_prev(pos, head) \
	for (pos = (head)->prev; prefetch (pos->prev), pos != (head); \
	     pos = pos->prev)

/**
 * list_for_each_safe - iterate over a list safe against removal of list entry
 * @pos:  the &struct list_head to use as a loop counter.
 * @n:    another &struct list_head to use as temporary storage
 * @head: the head for your list.
 */
#define list_for_each_safe(pos, n, head) \
	for (pos = (head)->next, n = pos->next; pos != (head); \
	     pos = n, n = pos->next)

/**
 * list_for_each_entry  - iterate over list of given type
 * @pos:  the type * to use as a loop counter.
 * @head: the head for your list.
 * @member: the name of the list_struct within the struct.
 */
#define list_for_each_entry(pos, head, member)	      \
	for (pos = list_entry ((head)->next, typeof(*pos), member);  \
	     prefetch (pos->member.next), &pos->member != (head);  \
	     pos = list_entry (pos->member.next, typeof(*pos), member))

/**
 * list_for_each_entry_reverse - iterate backwards over list of given type.
 * @pos:  the type * to use as a loop counter.
 * @head: the head for your list.
 * @member: the name of the list_struct within the struct.
 */
#define list_for_each_entry_reverse(pos, head, member)	    \
	for (pos = list_entry ((head)->prev, typeof(*pos), member);  \
	     prefetch (pos->member.prev), &pos->member != (head);  \
	     pos = list_entry (pos->member.prev, typeof(*pos), member))

/**
 * list_prepare_entry - prepare a pos entry for use as a start point in
 *      list_for_each_entry_continue
 * @pos:  the type * to use as a start point
 * @head: the head of the list
 * @member: the name of the list_struct within the struct.
 */
#define list_prepare_entry(pos, head, member) \
	((pos) ? : list_entry (head, typeof(*pos), member))

/**
 * list_for_each_entry_continue - iterate over list of given type
 *      continuing after existing point
 * @pos:  the type * to use as a loop counter.
 * @head: the head for your list.
 * @member: the name of the list_struct within the struct.
 */
#define list_for_each_entry_continue(pos, head, member)	    \
	for (pos = list_entry (pos->member.next, typeof(*pos), member);	 \
	     prefetch (pos->member.next), &pos->member != (head);  \
	     pos = list_entry (pos->member.next, typeof(*pos), member))

/**
 * list_for_each_entry_from - iterate over list of given type
 *      continuing from existing point
 * @pos:  the type * to use as a loop counter.
 * @head: the head for your list.
 * @member: the name of the list_struct within the struct.
 */
#define list_for_each_entry_from(pos, head, member)	  \
	for (; prefetch (pos->member.next), &pos->member != (head);  \
	     pos = list_entry (pos->member.next, typeof(*pos), member))

/**
 * list_for_each_entry_safe - iterate over list of given type safe against removal of list entry
 * @pos:  the type * to use as a loop counter.
 * @n:    another type * to use as temporary storage
 * @head: the head for your list.
 * @member: the name of the list_struct within the struct.
 */
#define list_for_each_entry_safe(pos, n, head, member)	    \
	for (pos = list_entry ((head)->next, typeof(*pos), member),  \
	     n = list_entry (pos->member.next, typeof(*pos), member); \
	     &pos->member != (head);	      \
	     pos = n, n = list_entry (n->member.next, typeof(*n), member))

/**
 * list_for_each_entry_safe_continue -  iterate over list of given type
 *      continuing after existing point safe against removal of list entry
 * @pos:  the type * to use as a loop counter.
 * @n:    another type * to use as temporary storage
 * @head: the head for your list.
 * @member: the name of the list_struct within the struct.
 */
#define list_for_each_entry_safe_continue(pos, n, head, member)	    \
	for (pos = list_entry (pos->member.next, typeof(*pos), member),	   \
	     n = list_entry (pos->member.next, typeof(*pos), member);	\
	     &pos->member != (head);		\
	     pos = n, n = list_entry (n->member.next, typeof(*n), member))

/**
 * list_for_each_entry_safe_from - iterate over list of given type
 *      from existing point safe against removal of list entry
 * @pos:  the type * to use as a loop counter.
 * @n:    another type * to use as temporary storage
 * @head: the head for your list.
 * @member: the name of the list_struct within the struct.
 */
#define list_for_each_entry_safe_from(pos, n, head, member)	  \
	for (n = list_entry (pos->member.next, typeof(*pos), member);	 \
	     &pos->member != (head);		\
	     pos = n, n = list_entry (n->member.next, typeof(*n), member))

/**
 * list_for_each_entry_safe_reverse - iterate backwards over list of given type safe against
 *              removal of list entry
 * @pos:  the type * to use as a loop counter.
 * @n:    another type * to use as temporary storage
 * @head: the head for your list.
 * @member: the name of the list_struct within the struct.
 */
#define list_for_each_entry_safe_reverse(pos, n, head, member)	  \
	for (pos = list_entry ((head)->prev, typeof(*pos), member),  \
	     n = list_entry (pos->member.prev, typeof(*pos), member); \
	     &pos->member != (head);	      \
	     pos = n, n = list_entry (n->member.prev, typeof(*n), member))

/**
 * list_for_each_rcu  - iterate over an rcu-protected list
 * @pos:  the &struct list_head to use as a loop counter.
 * @head: the head for your list.
 *
 * 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_rcu(pos, head) \
	for (pos = (head)->next; \
	     prefetch (rcu_dereference (pos)->next), pos != (head); \
	     pos = pos->next)

#define __list_for_each_rcu(pos, head) \
	for (pos = (head)->next; \
	     rcu_dereference (pos) != (head); \
	     pos = pos->next)

/**
 * list_for_each_safe_rcu - iterate over an rcu-protected list safe
 *          against removal of list entry
 * @pos:  the &struct list_head to use as a loop counter.
 * @n:    another &struct list_head to use as temporary storage
 * @head: the head for your list.
 *
 * 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_safe_rcu(pos, n, head) \
	for (pos = (head)->next; \
	     n = rcu_dereference (pos)->next, pos != (head); \
	     pos = n)

/**
 * list_for_each_entry_rcu  - iterate over rcu list of given type
 * @pos:  the type * to use as a loop counter.
 * @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 ((head)->next, typeof(*pos), member); \
	     prefetch (rcu_dereference (pos)->member.next), \
	     &pos->member != (head); \
	     pos = list_entry (pos->member.next, typeof(*pos), member))


/**
 * list_for_each_continue_rcu - iterate over an rcu-protected list
 *      continuing after existing point.
 * @pos:  the &struct list_head to use as a loop counter.
 * @head: the head for your list.
 *
 * 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) = (pos)->next; \
	     prefetch (rcu_dereference ((pos))->next), (pos) != (head);	\
	     (pos) = (pos)->next)

/*
 * Double linked lists with a single pointer list head.
 * Mostly useful for hash tables where the two pointer list head is
 * too wasteful.
 * You lose the ability to access the tail in O(1).
 */

struct hlist_head {
	struct hlist_node *first;
};

struct hlist_node {
	struct hlist_node *next, **pprev;
};

#define HLIST_HEAD_INIT { .first = NULL }
#define HLIST_HEAD(name) struct hlist_head name = {  .first	= NULL }
#define INIT_HLIST_HEAD(ptr) ((ptr)->first = NULL)
static inline void INIT_HLIST_NODE (struct hlist_node *h)
{
	h->next = NULL;
	h->pprev = NULL;
}

static inline int hlist_unhashed (const struct hlist_node *h)
{
	return !h->pprev;
}

static inline int hlist_empty (const struct hlist_head *h)
{
	return !h->first;
}

static inline void __hlist_del (struct hlist_node *n)
{
	struct hlist_node *next = n->next;
	struct hlist_node **pprev = n->pprev;

	*pprev = next;
	if (next) {
		next->pprev = pprev;
	}
}

static inline void hlist_del (struct hlist_node *n)
{
	__hlist_del (n);
	n->next = LIST_POISON1;
	n->pprev = LIST_POISON2;
}

/**
 * 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;
}

static inline void hlist_del_init (struct hlist_node *n)
{
	if (!hlist_unhashed (n)) {
		__hlist_del (n);
		INIT_HLIST_NODE (n);
	}
}

/*
 * 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;
//  smp_wmb();
	if (next) {
		new->next->pprev = &new->next;
	}
	*new->pprev = new;
	old->pprev = LIST_POISON2;
}

static inline void hlist_add_head (struct hlist_node *n, struct hlist_head *h)
{
	struct hlist_node *first = h->first;

	n->next = first;
	if (first) {
		first->pprev = &n->next;
	}
	h->first = n;
	n->pprev = &h->first;
}


/**
 * hlist_add_head_rcu - adds the specified element to the specified hlist,
 * while permitting racing traversals.
 * @n: the element to add to the hash list.
 * @h: the list to add to.
 *
 * 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;
//  smp_wmb();
	if (first) {
		first->pprev = &n->next;
	}
	h->first = n;
}

/* next must be != NULL */
static inline void hlist_add_before (struct hlist_node *n,
				     struct hlist_node *next)
{
	n->pprev = next->pprev;
	n->next = next;
	next->pprev = &n->next;
	*(n->pprev) = n;
}

static inline void hlist_add_after (struct hlist_node *n,
				    struct hlist_node *next)
{
	next->next = n->next;
	n->next = next;
	next->pprev = &n->next;

	if (next->next) {
		next->next->pprev  = &next->next;
	}
}

/**
 * hlist_add_before_rcu - adds the specified element to the specified hlist
 * before the specified node while permitting racing traversals.
 * @n: the new element to add to the hash list.
 * @next: the existing element to add the new element before.
 *
 * 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;
//  smp_wmb();
	next->pprev = &n->next;
	*(n->pprev) = n;
}

/**
 * hlist_add_after_rcu - adds the specified element to the specified hlist
 * after the specified node while permitting racing traversals.
 * @prev: the existing element to add the new element after.
 * @n: the new element to add to 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_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;
//  smp_wmb();
	prev->next = n;
	if (n->next) {
		n->next->pprev = &n->next;
	}
}

#define hlist_entry(ptr, type, member) container_of (ptr, type, member)

#define hlist_for_each(pos, head) \
	for (pos = (head)->first; pos && ({ prefetch (pos->next); 1; }); \
	     pos = pos->next)

#define hlist_for_each_safe(pos, n, head) \
	for (pos = (head)->first; pos && ({ n = pos->next; 1; }); \
	     pos = n)

/**
 * hlist_for_each_entry - iterate over list of given type
 * @tpos: the type * to use as a loop counter.
 * @pos:  the &struct hlist_node to use as a loop counter.
 * @head: the head for your list.
 * @member: the name of the hlist_node within the struct.
 */
#define hlist_for_each_entry(tpos, pos, head, member)	   \
	for (pos = (head)->first;	   \
	     pos && ({ prefetch (pos->next); 1; }) &&	   \
	     ({ tpos = hlist_entry (pos, typeof(*tpos), member); 1; });	\
	     pos = pos->next)

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

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

/**
 * hlist_for_each_entry_safe - iterate over list of given type safe against removal of list entry
 * @tpos: the type * to use as a loop counter.
 * @pos:  the &struct hlist_node to use as a loop counter.
 * @n:    another &struct hlist_node to use as temporary storage
 * @head: the head for your list.
 * @member: the name of the hlist_node within the struct.
 */
#define hlist_for_each_entry_safe(tpos, pos, n, head, member)	   \
	for (pos = (head)->first;	   \
	     pos && ({ n = pos->next; 1; }) &&	       \
	     ({ tpos = hlist_entry (pos, typeof(*tpos), member); 1; });	\
	     pos = n)

/**
 * hlist_for_each_entry_rcu - iterate over rcu list of given type
 * @tpos: the type * to use as a loop counter.
 * @pos:  the &struct hlist_node to use as a loop counter.
 * @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 = (head)->first;	   \
	     rcu_dereference (pos) && ({ prefetch (pos->next); 1; }) &&	  \
	     ({ tpos = hlist_entry (pos, typeof(*tpos), member); 1; });	\
	     pos = pos->next)

#endif

/**
 * __list_sort - sort the list using given comparator with merge-sort algorithm
 * @head: is a head of the list to be sorted
 * @member_offset: is machine offset inside the list entry structure to the
 *                 field of type struct list_head which links that entry with
 *                 the list.
 */
extern void __list_sort(struct list_head * head,
			int member_offset,
			int (*comparator)(void*, void*));

/**
 * list_sort - wrapper for __list_sort
 * @head: is a head of the list to be sorted
 * @type: is the type of list entry
 * @member: is the name of the field inside entry that links that entry with
 *          other entries in the list.
 * @comaprator: function comparing two entries, should return value lesser
 *              than 0 when the first argument is lesser than the second one.
 */
#define list_sort(head, type, member, comparator)			  \
	({								\
		 __list_sort (head,					  \
			      offsetof (type, member),			   \
			      (int (*)(void*, void*))comparator);	 \
	 })

void test_list_sort(void);