linux内核链表的实现

.\linux-2.6.22.6_vscode\include\linux\list.h

#ifndef _LINUX_LIST_H
#define _LINUX_LIST_H

#ifdef __KERNEL__

#include <linux/stddef.h>
#include <linux/poison.h>
#include <linux/prefetch.h>
#include <asm/system.h>

/*
* 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.

*/

 

//链表头

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

 
 

//（静态）初始化链表头

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

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

 
 

//（动态）初始化链表头

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!
*/
#ifndef CONFIG_DEBUG_LIST
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;
}
#else
extern void __list_add(struct list_head *new,
                         struct list_head *prev,
                         struct list_head *next);
#endif

/**
* 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.
*/
#ifndef CONFIG_DEBUG_LIST
static inline void list_add(struct list_head *new, struct list_head *head)
{
        __list_add(new, head, head->next);
}
#else
extern void list_add(struct list_head *new, struct list_head *head);
#endif

/**
* 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(); //smp_wmb()防止编译器和CPU优化代码执行的顺序。在这里，smp_wmb保证在它之前的两行代码执行完了之后再执行后两行.

//如果没有smp_wmb，代码在CPU中执行的顺序可能和源代码里的不一样!

        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.
*/
#ifndef CONFIG_DEBUG_LIST
static inline void list_del(struct list_head *entry)
{
        __list_del(entry->prev, entry->next);
        entry->next = LIST_POISON1;
        entry->prev = LIST_POISON2;
}
#else
extern void list_del(struct list_head *entry);
#endif

/**
* 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 - replace old entry by new one
* @old : the element to be replaced
* @new : the new element to insert
*
* If @old was empty, it will be overwritten.
*/
static inline void list_replace(struct
list_head *old,
                                struct list_head *new)
{
        new->next = old->next;
        new->next->prev = new;
        new->prev = old->prev;
        new->prev->next = new;
}

static inline void list_replace_init(struct list_head *old,
                                        struct list_head *new)
{
        list_replace(old, new);
        INIT_LIST_HEAD(old);
}

/**
* 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;
        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_is_last - tests whether @list is the last entry in list @head
* @list: the entry to test
* @head: the head of the list
*/
static inline int list_is_last(const struct list_head *list,
                                const struct list_head *head)
{
        return list->next == 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 not being modified
* @head: the list to test
*
* Description:
* tests whether a list is empty _and_ checks that no other CPU might be
* in the process of modifying either member (next or prev)
*
* 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.
*/
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,
357                                  struct list_head *head)
358 {
359         if (!list_empty(list)) {
360                 __list_splice(list, head);
361                 INIT_LIST_HEAD(list);
362         }
363 }
364
365 /**
366 * list_splice_init_rcu - splice an RCU-protected list into an existing list.
367 * @list:        the RCU-protected list to splice
368 * @head:        the place in the list to splice the first list into
369 * @sync:        function to sync: synchronize_rcu(), synchronize_sched(), ...
370 *
371 * @head can be RCU-read traversed concurrently with this function.
372 *
373 * Note that this function blocks.
374 *
375 * Important note: the caller must take whatever action is necessary to
376 *        prevent any other updates to @head. In principle, it is possible
377 *        to modify the list as soon as sync() begins execution.
378 *        If this sort of thing becomes necessary, an alternative version
379 *        based on call_rcu() could be created. But only if -really-
380 *        needed -- there is no shortage of RCU API members.
381 */
382 static inline void list_splice_init_rcu(struct list_head *list,
383                                         struct list_head *head,
384                                         void (*sync)(void))
385 {
386         struct list_head *first = list->next;
387         struct list_head *last = list->prev;
388         struct list_head *at = head->next;
389
390         if (list_empty(head))
391                 return;
392
393         /* "first" and "last" tracking list, so initialize it. */
394
395         INIT_LIST_HEAD(list);
396
397         /*
398          * At this point, the list body still points to the source list.
399          * Wait for any readers to finish using the list before splicing
400          * the list body into the new list. Any new readers will see
401          * an empty list.
402          */
403
404         sync();
405
406         /*
407          * Readers are finished with the source list, so perform splice.
408          * The order is important if the new list is global and accessible
409          * to concurrent RCU readers. Note that RCU readers are not
410          * permitted to traverse the prev pointers without excluding
411          * this function.
412          */
413
414         last->next = at;
415         smp_wmb();
416         head->next = first;
417         first->prev = head;
418         at->prev = last;
419 }
420
421 /**
422 * list_entry - get the struct for this entry
423 * @ptr:        the &struct list_head pointer.
424 * @type:        the type of the struct this is embedded in.
425 * @member:        the name of the list_struct within the struct.
426 */
427 #define list_entry(ptr, type, member) \
428         container_of(ptr, type, member)
429
430 /**
431 * list_first_entry - get the first element from a list
432 * @ptr:        the list head to take the element from.
433 * @type:        the type of the struct this is embedded in.
434 * @member:        the name of the list_struct within the struct.
435 *
436 * Note, that list is expected to be not empty.
437 */
438 #define list_first_entry(ptr, type, member) \
439         list_entry((ptr)->next, type, member)
440
441 /**
442 * list_for_each        -        iterate over a list
443 * @pos:        the &struct list_head to use as a loop cursor.
444 * @head:        the head for your list.
445 */
446 #define list_for_each(pos, head) \
447         for (pos = (head)->next; prefetch(pos->next), pos != (head); \
448         pos = pos->next)
449
450 /**
451 * __list_for_each        -        iterate over a list
452 * @pos:        the &struct list_head to use as a loop cursor.
453 * @head:        the head for your list.
454 *
455 * This variant differs from list_for_each() in that it's the
456 * simplest possible list iteration code, no prefetching is done.
457 * Use this for code that knows the list to be very short (empty
458 * or 1 entry) most of the time.
459 */
460 #define __list_for_each(pos, head) \
461         for (pos = (head)->next; pos != (head); pos = pos->next)
462
463 /**
464 * list_for_each_prev        -        iterate over a list backwards
465 * @pos:        the &struct list_head to use as a loop cursor.
466 * @head:        the head for your list.
467 */
468 #define list_for_each_prev(pos, head) \
469         for (pos = (head)->prev; prefetch(pos->prev), pos != (head); \
470         pos = pos->prev)
471
472 /**
473 * list_for_each_safe - iterate over a list safe against removal of list entry
474 * @pos:        the &struct list_head to use as a loop cursor.
475 * @n:                another &struct list_head to use as temporary storage
476 * @head:        the head for your list.
477 */
478 #define list_for_each_safe(pos, n, head) \
479         for (pos = (head)->next, n = pos->next; pos != (head); \
480                 pos = n, n = pos->next)
481
482 /**
483 * list_for_each_entry        -        iterate over list of given type
484 * @pos:        the type * to use as a loop cursor.
485 * @head:        the head for your list.
486 * @member:        the name of the list_struct within the struct.
487 */
488 #define list_for_each_entry(pos, head, member)                                \
489         for (pos = list_entry((head)->next, typeof(*pos), member);        \
490          prefetch(pos->member.next), &pos->member != (head);         \
491          pos = list_entry(pos->member.next, typeof(*pos), member))
492
493 /**
494 * list_for_each_entry_reverse - iterate backwards over list of given type.
495 * @pos:        the type * to use as a loop cursor.
496 * @head:        the head for your list.
497 * @member:        the name of the list_struct within the struct.
498 */
499 #define list_for_each_entry_reverse(pos, head, member)                        \
500         for (pos = list_entry((head)->prev, typeof(*pos), member);        \
501          prefetch(pos->member.prev), &pos->member != (head);         \
502          pos = list_entry(pos->member.prev, typeof(*pos), member))
503
504 /**
505 * list_prepare_entry - prepare a pos entry for use in list_for_each_entry_continue()
506 * @pos:        the type * to use as a start point
507 * @head:        the head of the list
508 * @member:        the name of the list_struct within the struct.
509 *
510 * Prepares a pos entry for use as a start point in list_for_each_entry_continue().
511 */
512 #define list_prepare_entry(pos, head, member) \
513         ((pos) ? : list_entry(head, typeof(*pos), member))
514
515 /**
516 * list_for_each_entry_continue - continue iteration over list of given type
517 * @pos:        the type * to use as a loop cursor.
518 * @head:        the head for your list.
519 * @member:        the name of the list_struct within the struct.
520 *
521 * Continue to iterate over list of given type, continuing after
522 * the current position.
523 */
524 #define list_for_each_entry_continue(pos, head, member)                 \
525         for (pos = list_entry(pos->member.next, typeof(*pos), member);        \
526          prefetch(pos->member.next), &pos->member != (head);        \
527          pos = list_entry(pos->member.next, typeof(*pos), member))
528
529 /**
530 * list_for_each_entry_from - iterate over list of given type from the current point
531 * @pos:        the type * to use as a loop cursor.
532 * @head:        the head for your list.
533 * @member:        the name of the list_struct within the struct.
534 *
535 * Iterate over list of given type, continuing from current position.
536 */
537 #define list_for_each_entry_from(pos, head, member)                         \
538         for (; prefetch(pos->member.next), &pos->member != (head);        \
539          pos = list_entry(pos->member.next, typeof(*pos), member))
540
541 /**
542 * list_for_each_entry_safe - iterate over list of given type safe against removal of list entry
543 * @pos:        the type * to use as a loop cursor.
544 * @n:                another type * to use as temporary storage
545 * @head:        the head for your list.
546 * @member:        the name of the list_struct within the struct.
547 */
548 #define list_for_each_entry_safe(pos, n, head, member)                        \
549         for (pos = list_entry((head)->next, typeof(*pos), member),        \
550                 n = list_entry(pos->member.next, typeof(*pos), member);        \
551          &pos->member != (head);                                         \
552          pos = n, n = list_entry(n->member.next, typeof(*n), member))
553
554 /**
555 * list_for_each_entry_safe_continue
556 * @pos:        the type * to use as a loop cursor.
557 * @n:                another type * to use as temporary storage
558 * @head:        the head for your list.
559 * @member:        the name of the list_struct within the struct.
560 *
561 * Iterate over list of given type, continuing after current point,
562 * safe against removal of list entry.
563 */
564 #define list_for_each_entry_safe_continue(pos, n, head, member)                 \
565         for (pos = list_entry(pos->member.next, typeof(*pos), member),                 \
566                 n = list_entry(pos->member.next, typeof(*pos), member);                \
567          &pos->member != (head);                                                \
568          pos = n, n = list_entry(n->member.next, typeof(*n), member))
569
570 /**
571 * list_for_each_entry_safe_from
572 * @pos:        the type * to use as a loop cursor.
573 * @n:                another type * to use as temporary storage
574 * @head:        the head for your list.
575 * @member:        the name of the list_struct within the struct.
576 *
577 * Iterate over list of given type from current point, safe against
578 * removal of list entry.
579 */
580 #define list_for_each_entry_safe_from(pos, n, head, member)                         \
581         for (n = list_entry(pos->member.next, typeof(*pos), member);                \
582          &pos->member != (head);                                                \
583          pos = n, n = list_entry(n->member.next, typeof(*n), member))
584
585 /**
586 * list_for_each_entry_safe_reverse
587 * @pos:        the type * to use as a loop cursor.
588 * @n:                another type * to use as temporary storage
589 * @head:        the head for your list.
590 * @member:        the name of the list_struct within the struct.
591 *
592 * Iterate backwards over list of given type, safe against removal
593 * of list entry.
594 */
595 #define list_for_each_entry_safe_reverse(pos, n, head, member)                \
596         for (pos = list_entry((head)->prev, typeof(*pos), member),        \
597                 n = list_entry(pos->member.prev, typeof(*pos), member);        \
598          &pos->member != (head);                                         \
599          pos = n, n = list_entry(n->member.prev, typeof(*n), member))
600
601 /**
602 * list_for_each_rcu        -        iterate over an rcu-protected list
603 * @pos:        the &struct list_head to use as a loop cursor.
604 * @head:        the head for your list.
605 *
606 * This list-traversal primitive may safely run concurrently with
607 * the _rcu list-mutation primitives such as list_add_rcu()
608 * as long as the traversal is guarded by rcu_read_lock().
609 */
610 #define list_for_each_rcu(pos, head) \
611         for (pos = (head)->next; \
612                 prefetch(rcu_dereference(pos)->next), pos != (head); \
613         pos = pos->next)
614
615 #define __list_for_each_rcu(pos, head) \
616         for (pos = (head)->next; \
617                 rcu_dereference(pos) != (head); \
618         pos = pos->next)
619
620 /**
621 * list_for_each_safe_rcu
622 * @pos:        the &struct list_head to use as a loop cursor.
623 * @n:                another &struct list_head to use as temporary storage
624 * @head:        the head for your list.
625 *
626 * Iterate over an rcu-protected list, safe against removal of list entry.
627 *
628 * This list-traversal primitive may safely run concurrently with
629 * the _rcu list-mutation primitives such as list_add_rcu()
630 * as long as the traversal is guarded by rcu_read_lock().
631 */
632 #define list_for_each_safe_rcu(pos, n, head) \
633         for (pos = (head)->next; \
634                 n = rcu_dereference(pos)->next, pos != (head); \
635                 pos = n)
636
637 /**
638 * list_for_each_entry_rcu        -        iterate over rcu list of given type
639 * @pos:        the type * to use as a loop cursor.
640 * @head:        the head for your list.
641 * @member:        the name of the list_struct within the struct.
642 *
643 * This list-traversal primitive may safely run concurrently with
644 * the _rcu list-mutation primitives such as list_add_rcu()
645 * as long as the traversal is guarded by rcu_read_lock().
646 */
647 #define list_for_each_entry_rcu(pos, head, member) \
648         for (pos = list_entry((head)->next, typeof(*pos), member); \
649                 prefetch(rcu_dereference(pos)->member.next), \
650                         &pos->member != (head); \
651                 pos = list_entry(pos->member.next, typeof(*pos), member))
652
653
654 /**
655 * list_for_each_continue_rcu
656 * @pos:        the &struct list_head to use as a loop cursor.
657 * @head:        the head for your list.
658 *
659 * Iterate over an rcu-protected list, continuing after current point.
660 *
661 * This list-traversal primitive may safely run concurrently with
662 * the _rcu list-mutation primitives such as list_add_rcu()
663 * as long as the traversal is guarded by rcu_read_lock().
664 */
665 #define list_for_each_continue_rcu(pos, head) \
666         for ((pos) = (pos)->next; \
667                 prefetch(rcu_dereference((pos))->next), (pos) != (head); \
668         (pos) = (pos)->next)
669
670 /*
671 * Double linked lists with a single pointer list head.
672 * Mostly useful for hash tables where the two pointer list head is
673 * too wasteful.
674 * You lose the ability to access the tail in O(1).
675 */
676
677 struct hlist_head {
678         struct hlist_node *first;
679 };
680
681 struct hlist_node {
682         struct hlist_node *next, **pprev;
683 };
684
685 #define HLIST_HEAD_INIT { .first = NULL }
686 #define HLIST_HEAD(name) struct hlist_head name = { .first = NULL }
687 #define INIT_HLIST_HEAD(ptr) ((ptr)->first = NULL)
688 static inline void INIT_HLIST_NODE(struct hlist_node *h)
689 {
690         h->next = NULL;
691         h->pprev = NULL;
692 }
693
694 static inline int hlist_unhashed(const struct hlist_node *h)
695 {
696         return !h->pprev;
697 }
698
699 static inline int hlist_empty(const struct hlist_head *h)
700 {
701         return !h->first;
702 }
703
704 static inline void __hlist_del(struct hlist_node *n)
705 {
706         struct hlist_node *next = n->next;
707         struct hlist_node **pprev = n->pprev;
708         *pprev = next;
709         if (next)
710                 next->pprev = pprev;
711 }
712
713 static inline void hlist_del(struct hlist_node *n)
714 {
715         __hlist_del(n);
716         n->next = LIST_POISON1;
717         n->pprev = LIST_POISON2;
718 }
719
720 /**
721 * hlist_del_rcu - deletes entry from hash list without re-initialization
722 * @n: the element to delete from the hash list.
723 *
724 * Note: list_unhashed() on entry does not return true after this,
725 * the entry is in an undefined state. It is useful for RCU based
726 * lockfree traversal.
727 *
728 * In particular, it means that we can not poison the forward
729 * pointers that may still be used for walking the hash list.
730 *
731 * The caller must take whatever precautions are necessary
732 * (such as holding appropriate locks) to avoid racing
733 * with another list-mutation primitive, such as hlist_add_head_rcu()
734 * or hlist_del_rcu(), running on this same list.
735 * However, it is perfectly legal to run concurrently with
736 * the _rcu list-traversal primitives, such as
737 * hlist_for_each_entry().
738 */
739 static inline void hlist_del_rcu(struct hlist_node *n)
740 {
741         __hlist_del(n);
742         n->pprev = LIST_POISON2;
743 }
744
745 static inline void hlist_del_init(struct hlist_node *n)
746 {
747         if (!hlist_unhashed(n)) {
748                 __hlist_del(n);
749                 INIT_HLIST_NODE(n);
750         }
751 }
752
753 /**
754 * hlist_replace_rcu - replace old entry by new one
755 * @old : the element to be replaced
756 * @new : the new element to insert
757 *
758 * The @old entry will be replaced with the @new entry atomically.
759 */
760 static inline void hlist_replace_rcu(struct hlist_node *old,
761                                         struct hlist_node *new)
762 {
763         struct hlist_node *next = old->next;
764
765         new->next = next;
766         new->pprev = old->pprev;
767         smp_wmb();
768         if (next)
769                 new->next->pprev = &new->next;
770         *new->pprev = new;
771         old->pprev = LIST_POISON2;
772 }
773
774 static inline void hlist_add_head(struct hlist_node *n, struct hlist_head *h)
775 {
776         struct hlist_node *first = h->first;
777         n->next = first;
778         if (first)
779                 first->pprev = &n->next;
780         h->first = n;
781         n->pprev = &h->first;
782 }
783
784
785 /**
786 * hlist_add_head_rcu
787 * @n: the element to add to the hash list.
788 * @h: the list to add to.
789 *
790 * Description:
791 * Adds the specified element to the specified hlist,
792 * while permitting racing traversals.
793 *
794 * The caller must take whatever precautions are necessary
795 * (such as holding appropriate locks) to avoid racing
796 * with another list-mutation primitive, such as hlist_add_head_rcu()
797 * or hlist_del_rcu(), running on this same list.
798 * However, it is perfectly legal to run concurrently with
799 * the _rcu list-traversal primitives, such as
800 * hlist_for_each_entry_rcu(), used to prevent memory-consistency
801 * problems on Alpha CPUs. Regardless of the type of CPU, the
802 * list-traversal primitive must be guarded by rcu_read_lock().
803 */
804 static inline void hlist_add_head_rcu(struct hlist_node *n,
805                                         struct hlist_head *h)
806 {
807         struct hlist_node *first = h->first;
808         n->next = first;
809         n->pprev = &h->first;
810         smp_wmb();
811         if (first)
812                 first->pprev = &n->next;
813         h->first = n;
814 }
815
816 /* next must be != NULL */
817 static inline void hlist_add_before(struct hlist_node *n,
818                                         struct hlist_node *next)
819 {
820         n->pprev = next->pprev;
821         n->next = next;
822         next->pprev = &n->next;
823         *(n->pprev) = n;
824 }
825
826 static inline void hlist_add_after(struct hlist_node *n,
827                                         struct hlist_node *next)
828 {
829         next->next = n->next;
830         n->next = next;
831         next->pprev = &n->next;
832
833         if(next->next)
834                 next->next->pprev = &next->next;
835 }
836
837 /**
838 * hlist_add_before_rcu
839 * @n: the new element to add to the hash list.
840 * @next: the existing element to add the new element before.
841 *
842 * Description:
843 * Adds the specified element to the specified hlist
844 * before the specified node while permitting racing traversals.
845 *
846 * The caller must take whatever precautions are necessary
847 * (such as holding appropriate locks) to avoid racing
848 * with another list-mutation primitive, such as hlist_add_head_rcu()
849 * or hlist_del_rcu(), running on this same list.
850 * However, it is perfectly legal to run concurrently with
851 * the _rcu list-traversal primitives, such as
852 * hlist_for_each_entry_rcu(), used to prevent memory-consistency
853 * problems on Alpha CPUs.
854 */
855 static inline void hlist_add_before_rcu(struct hlist_node *n,
856                                         struct hlist_node *next)
857 {
858         n->pprev = next->pprev;
859         n->next = next;
860         smp_wmb();
861         next->pprev = &n->next;
862         *(n->pprev) = n;
863 }
864
865 /**
866 * hlist_add_after_rcu
867 * @prev: the existing element to add the new element after.
868 * @n: the new element to add to the hash list.
869 *
870 * Description:
871 * Adds the specified element to the specified hlist
872 * after the specified node while permitting racing traversals.
873 *
874 * The caller must take whatever precautions are necessary
875 * (such as holding appropriate locks) to avoid racing
876 * with another list-mutation primitive, such as hlist_add_head_rcu()
877 * or hlist_del_rcu(), running on this same list.
878 * However, it is perfectly legal to run concurrently with
879 * the _rcu list-traversal primitives, such as
880 * hlist_for_each_entry_rcu(), used to prevent memory-consistency
881 * problems on Alpha CPUs.
882 */
883 static inline void hlist_add_after_rcu(struct hlist_node *prev,
884                                  struct hlist_node *n)
885 {
886         n->next = prev->next;
887         n->pprev = &prev->next;
888         smp_wmb();
889         prev->next = n;
890         if (n->next)
891                 n->next->pprev = &n->next;
892 }
893
894 #define hlist_entry(ptr, type, member) container_of(ptr,type,member)
895
896 #define hlist_for_each(pos, head) \
897         for (pos = (head)->first; pos && ({ prefetch(pos->next); 1; }); \
898          pos = pos->next)
899
900 #define hlist_for_each_safe(pos, n, head) \
901         for (pos = (head)->first; pos && ({ n = pos->next; 1; }); \
902          pos = n)
903
904 /**
905 * hlist_for_each_entry        - iterate over list of given type
906 * @tpos:        the type * to use as a loop cursor.
907 * @pos:        the &struct hlist_node to use as a loop cursor.
908 * @head:        the head for your list.
909 * @member:        the name of the hlist_node within the struct.
910 */
911 #define hlist_for_each_entry(tpos, pos, head, member)                         \
912         for (pos = (head)->first;                                         \
913          pos && ({ prefetch(pos->next); 1;}) &&                         \
914                 ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \
915          pos = pos->next)
916
917 /**
918 * hlist_for_each_entry_continue - iterate over a hlist continuing after current point
919 * @tpos:        the type * to use as a loop cursor.
920 * @pos:        the &struct hlist_node to use as a loop cursor.
921 * @member:        the name of the hlist_node within the struct.
922 */
923 #define hlist_for_each_entry_continue(tpos, pos, member)                 \
924         for (pos = (pos)->next;                                                 \
925          pos && ({ prefetch(pos->next); 1;}) &&                         \
926                 ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \
927          pos = pos->next)
928
929 /**
930 * hlist_for_each_entry_from - iterate over a hlist continuing from current point
931 * @tpos:        the type * to use as a loop cursor.
932 * @pos:        the &struct hlist_node to use as a loop cursor.
933 * @member:        the name of the hlist_node within the struct.
934 */
935 #define hlist_for_each_entry_from(tpos, pos, member)                         \
936         for (; pos && ({ prefetch(pos->next); 1;}) &&                         \
937                 ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \
938          pos = pos->next)
939
940 /**
941 * hlist_for_each_entry_safe - iterate over list of given type safe against removal of list entry
942 * @tpos:        the type * to use as a loop cursor.
943 * @pos:        the &struct hlist_node to use as a loop cursor.
944 * @n:                another &struct hlist_node to use as temporary storage
945 * @head:        the head for your list.
946 * @member:        the name of the hlist_node within the struct.
947 */
948 #define hlist_for_each_entry_safe(tpos, pos, n, head, member)                  \
949         for (pos = (head)->first;                                         \
950          pos && ({ n = pos->next; 1; }) &&                                  \
951                 ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \
952          pos = n)
953
954 /**
955 * hlist_for_each_entry_rcu - iterate over rcu list of given type
956 * @tpos:        the type * to use as a loop cursor.
957 * @pos:        the &struct hlist_node to use as a loop cursor.
958 * @head:        the head for your list.
959 * @member:        the name of the hlist_node within the struct.
960 *
961 * This list-traversal primitive may safely run concurrently with
962 * the _rcu list-mutation primitives such as hlist_add_head_rcu()
963 * as long as the traversal is guarded by rcu_read_lock().
964 */
965 #define hlist_for_each_entry_rcu(tpos, pos, head, member)                 \
966         for (pos = (head)->first;                                         \
967          rcu_dereference(pos) && ({ prefetch(pos->next); 1;}) &&         \
968                 ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \
969          pos = pos->next)
970
971 #else
972 #warning "don't include kernel headers in userspace"
973 #endif /* __KERNEL__ */
974 #endif

十

 
 

九

 
 

`。