基于Linux-5.10
一、说明
plist主要在Linux内核的Qos子系统中使用。将 plist_node::prio作为优先级，数值小的挂在链表前面，数值大的挂在链表后面。plist里面虽然包含双重循环链表，但是还是按单重循环的形式使用，plist认为其上的基本元素还是plist_node结构，add/delete认为的元素都还是plist_node结构。只不过相同优先级的元素挂在同一个plist_node节点的元素上了。prio相同的情况下，是FIFO的，先插入的挂在node_list链表的前面，后插入的挂在后面。
二、移植后文件
1. plist依赖于双向链表，双向链表文件如下：
/* 总结： 1. 一个entry同一时间只能添加到一个链表上，若在一个链表上，又添加到另一个链表上，有可能造成遍历时死循环。 2. entry没有必要进行初始化，但是head若不使用 INIT_LIST_HEAD() 进行初始化，使用时会产生段错误。 3. list_add()是头插法，最后插入的对象由head->next指向。 4. list_for_each()和list_for_each_entry()都是使用head->next进行正向遍历，前者返回list_add结构指针，后者返回执行链表上挂载成员的指针。 5. 带safe的只是多个一个备份，可以安全地删除取出来的元素。 */ /* SPDX-License-Identifier: GPL-2.0 来自include/linux/list.h*/ #ifndef _LINUX_LIST_H #define _LINUX_LIST_H #include <stddef.h> /*------------------I add--------------- */ #define WRITE_ONCE(var, val) (*((volatile typeof(val) *)(&(var))) = (val)) #define READ_ONCE(var) (*((volatile typeof(var) *)(&(var)))) struct list_head { struct list_head *next, *prev; }; struct hlist_head { struct hlist_node *first; }; struct hlist_node { struct hlist_node *next, **pprev; }; typedef _Bool bool; enum { false = 0, true = 1 }; #define NULL ((void *)0) #define LIST_POISON1 ((void *) 0x00100100) #define LIST_POISON2 ((void *) 0x00200200) /** * 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 offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER) //already defined in stddef.h #define container_of(ptr, type, member) ({ \ const typeof( ((type *)0)->member ) *__mptr = (ptr); \ (type *)( (char *)__mptr - offsetof(type,member) );}) /*------------------end----------------- */ /* * 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. */ #define LIST_HEAD_INIT(name) { &(name), &(name) } #define LIST_HEAD(name) \ struct list_head name = LIST_HEAD_INIT(name) /*head使用前必须要init，否则会段错误*/ static inline void INIT_LIST_HEAD(struct list_head *list) { WRITE_ONCE(list->next, list); list->prev = list; } #ifdef CONFIG_DEBUG_LIST extern bool __list_add_valid(struct list_head *new, struct list_head *prev, struct list_head *next); extern bool __list_del_entry_valid(struct list_head *entry); #else static inline bool __list_add_valid(struct list_head *new, struct list_head *prev, struct list_head *next) { return true; } static inline bool __list_del_entry_valid(struct list_head *entry) { return true; } #endif /* * 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) { if (!__list_add_valid(new, prev, next)) return; next->prev = new; new->next = next; new->prev = prev; WRITE_ONCE(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. */ /*头插法，最后插入的元素被head->next指向*/ 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. */ /*尾插法，最后一个插入的被head->prev指向*/ static inline void list_add_tail(struct list_head *new, struct list_head *head) { __list_add(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! */ /*传入的参数是要被删除节点的前一个和后一个的list_head成员的地址*/ static inline void __list_del(struct list_head * prev, struct list_head * next) { next->prev = prev; WRITE_ONCE(prev->next, next); } /* * Delete a list entry and clear the 'prev' pointer. * * This is a special-purpose list clearing method used in the networking code * for lists allocated as per-cpu, where we don't want to incur the extra * WRITE_ONCE() overhead of a regular list_del_init(). The code that uses this * needs to check the node 'prev' pointer instead of calling list_empty(). */ static inline void __list_del_clearprev(struct list_head *entry) { __list_del(entry->prev, entry->next); entry->prev = NULL; } /** * 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_entry(struct list_head *entry) { if (!__list_del_entry_valid(entry)) return; __list_del(entry->prev, entry->next); } static inline void list_del(struct list_head *entry) { __list_del_entry(entry); entry->next = LIST_POISON1; 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; } /*删除后，被删除的节点的prev和next指针都指向自己*/ static inline void list_replace_init(struct list_head *old, struct list_head *new) { list_replace(old, new); INIT_LIST_HEAD(old); } /** * list_swap - replace entry1 with entry2 and re-add entry1 at entry2's position * @entry1: the location to place entry2 * @entry2: the location to place entry1 */ static inline void list_swap(struct list_head *entry1, struct list_head *entry2) { struct list_head *pos = entry2->prev; list_del(entry2); list_replace(entry1, entry2); if (pos == entry1) pos = entry2; list_add(entry1, pos); } /** * 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(entry); 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_entry(list); 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_entry(list); list_add_tail(list, head); } /** * list_bulk_move_tail - move a subsection of a list to its tail * @head: the head that will follow our entry * @first: first entry to move * @last: last entry to move, can be the same as first * * Move all entries between @first and including @last before @head. * All three entries must belong to the same linked list. */ static inline void list_bulk_move_tail(struct list_head *head, struct list_head *first, struct list_head *last) { first->prev->next = last->next; last->next->prev = first->prev; head->prev->next = first; first->prev = head->prev; last->next = head; head->prev = last; } /** * list_is_first -- tests whether @list is the first entry in list @head * @list: the entry to test * @head: the head of the list */ static inline int list_is_first(const struct list_head *list, const struct list_head *head) { return list->prev == 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 READ_ONCE(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); } /** * list_rotate_left - rotate the list to the left * @head: the head of the list */ static inline void list_rotate_left(struct list_head *head) { struct list_head *first; if (!list_empty(head)) { first = head->next; list_move_tail(first, head); } } /** * list_rotate_to_front() - Rotate list to specific item. * @list: The desired new front of the list. * @head: The head of the list. * * Rotates list so that @list becomes the new front of the list. */ static inline void list_rotate_to_front(struct list_head *list, struct list_head *head) { /* * Deletes the list head from the list denoted by @head and * places it as the tail of @list, this effectively rotates the * list so that @list is at the front. */ list_move_tail(head, list); } /** * list_is_singular - tests whether a list has just one entry. * @head: the list to test. */ static inline int list_is_singular(const struct list_head *head) { return !list_empty(head) && (head->next == head->prev); } static inline void __list_cut_position(struct list_head *list, struct list_head *head, struct list_head *entry) { struct list_head *new_first = entry->next; list->next = head->next; list->next->prev = list; list->prev = entry; entry->next = list; head->next = new_first; new_first->prev = head; } /** * list_cut_position - cut a list into two * @list: a new list to add all removed entries * @head: a list with entries * @entry: an entry within head, could be the head itself * and if so we won't cut the list * * This helper moves the initial part of @head, up to and * including @entry, from @head to @list. You should * pass on @entry an element you know is on @head. @list * should be an empty list or a list you do not care about * losing its data. * */ static inline void list_cut_position(struct list_head *list, struct list_head *head, struct list_head *entry) { if (list_empty(head)) return; if (list_is_singular(head) && (head->next != entry && head != entry)) return; if (entry == head) INIT_LIST_HEAD(list); else __list_cut_position(list, head, entry); } /** * list_cut_before - cut a list into two, before given entry * @list: a new list to add all removed entries * @head: a list with entries * @entry: an entry within head, could be the head itself * * This helper moves the initial part of @head, up to but * excluding @entry, from @head to @list. You should pass * in @entry an element you know is on @head. @list should * be an empty list or a list you do not care about losing * its data. * If @entry == @head, all entries on @head are moved to * @list. */ static inline void list_cut_before(struct list_head *list, struct list_head *head, struct list_head *entry) { if (head->next == entry) { INIT_LIST_HEAD(list); return; } list->next = head->next; list->next->prev = list; list->prev = entry->prev; list->prev->next = list; head->next = entry; entry->prev = head; } static inline void __list_splice(const struct list_head *list, struct list_head *prev, struct list_head *next) { struct list_head *first = list->next; struct list_head *last = list->prev; first->prev = prev; prev->next = first; last->next = next; next->prev = last; } /** * list_splice - join two lists, this is designed for stacks * @list: the new list to add. * @head: the place to add it in the first list. */ static inline void list_splice(const struct list_head *list, struct list_head *head) { if (!list_empty(list)) __list_splice(list, head, head->next); } /** * list_splice_tail - join two lists, each list being a queue * @list: the new list to add. * @head: the place to add it in the first list. */ static inline void list_splice_tail(struct list_head *list, struct list_head *head) { if (!list_empty(list)) __list_splice(list, head->prev, 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, head->next); INIT_LIST_HEAD(list); } } /** * list_splice_tail_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. * * Each of the lists is a queue. * The list at @list is reinitialised */ static inline void list_splice_tail_init(struct list_head *list, struct list_head *head) { if (!list_empty(list)) { __list_splice(list, head->prev, 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_head within the struct. */ #define list_entry(ptr, type, member) \ container_of(ptr, type, member) /** * list_first_entry - 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_head within the struct. * * Note, that list is expected to be not empty. */ #define list_first_entry(ptr, type, member) \ list_entry((ptr)->next, type, member) /** * list_last_entry - get the last 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_head within the struct. * * Note, that list is expected to be not empty. */ #define list_last_entry(ptr, type, member) \ list_entry((ptr)->prev, type, member) /** * list_first_entry_or_null - 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_head within the struct. * * Note that if the list is empty, it returns NULL. */ #define list_first_entry_or_null(ptr, type, member) ({ \ struct list_head *head__ = (ptr); \ struct list_head *pos__ = READ_ONCE(head__->next); \ pos__ != head__ ? list_entry(pos__, type, member) : NULL; \ }) /** * list_next_entry - get the next element in list * @pos: the type * to cursor * @member: the name of the list_head within the struct. */ #define list_next_entry(pos, member) \ list_entry((pos)->member.next, typeof(*(pos)), member) /** * list_prev_entry - get the prev element in list * @pos: the type * to cursor * @member: the name of the list_head within the struct. */ #define list_prev_entry(pos, member) \ list_entry((pos)->member.prev, typeof(*(pos)), member) /** * list_for_each - iterate over a list * @pos: the &struct list_head to use as a loop cursor. * @head: the head for your list. */ /*返回的只是list_head类型的指针，非指向链表上成员的指针*/ #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 cursor. * @head: the head for your list. */ #define list_for_each_prev(pos, head) \ for (pos = (head)->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 cursor. * @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_prev_safe - iterate over a list backwards safe against removal of list entry * @pos: the &struct list_head to use as a loop cursor. * @n: another &struct list_head to use as temporary storage * @head: the head for your list. */ #define list_for_each_prev_safe(pos, n, head) \ for (pos = (head)->prev, n = pos->prev; \ pos != (head); \ pos = n, n = pos->prev) /** * list_for_each_entry - iterate 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_head within the struct. */ /*正序遍历，通过head->next成员进行遍历*/ #define list_for_each_entry(pos, head, member) \ for (pos = list_first_entry(head, typeof(*pos), member); \ &pos->member != (head); \ pos = list_next_entry(pos, member)) /** * list_for_each_entry_reverse - iterate backwards 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_head within the struct. */ #define list_for_each_entry_reverse(pos, head, member) \ for (pos = list_last_entry(head, typeof(*pos), member); \ &pos->member != (head); \ pos = list_prev_entry(pos, member)) /** * list_prepare_entry - prepare a pos entry for use 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_head within the struct. * * Prepares a pos entry for use as a start point in list_for_each_entry_continue(). */ #define list_prepare_entry(pos, head, member) \ ((pos) ? : list_entry(head, typeof(*pos), member)) /** * list_for_each_entry_continue - 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_head within the struct. * * Continue to iterate over list of given type, continuing after * the current position. */ #define list_for_each_entry_continue(pos, head, member) \ for (pos = list_next_entry(pos, member); \ &pos->member != (head); \ pos = list_next_entry(pos, member)) /** * list_for_each_entry_continue_reverse - iterate backwards from the given point * @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. * * Start to iterate over list of given type backwards, continuing after * the current position. */ #define list_for_each_entry_continue_reverse(pos, head, member) \ for (pos = list_prev_entry(pos, member); \ &pos->member != (head); \ pos = list_prev_entry(pos, member)) /** * list_for_each_entry_from - iterate over list of given type from the current point * @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. * * Iterate over list of given type, continuing from current position. */ #define list_for_each_entry_from(pos, head, member) \ for (; &pos->member != (head); \ pos = list_next_entry(pos, member)) /** * list_for_each_entry_from_reverse - iterate backwards over list of given type * from the current point * @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. * * Iterate backwards over list of given type, continuing from current position. */ #define list_for_each_entry_from_reverse(pos, head, member) \ for (; &pos->member != (head); \ pos = list_prev_entry(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 cursor. * @n: another type * to use as temporary storage * @head: the head for your list. * @member: the name of the list_head within the struct. */ #define list_for_each_entry_safe(pos, n, head, member) \ for (pos = list_first_entry(head, typeof(*pos), member), \ n = list_next_entry(pos, member); \ &pos->member != (head); \ pos = n, n = list_next_entry(n, member)) /** * list_for_each_entry_safe_continue - continue list iteration safe against removal * @pos: the type * to use as a loop cursor. * @n: another type * to use as temporary storage * @head: the head for your list. * @member: the name of the list_head within the struct. * * Iterate over list of given type, continuing after current point, * safe against removal of list entry. */ #define list_for_each_entry_safe_continue(pos, n, head, member) \ for (pos = list_next_entry(pos, member), \ n = list_next_entry(pos, member); \ &pos->member != (head); \ pos = n, n = list_next_entry(n, member)) /** * list_for_each_entry_safe_from - iterate over list from current point safe against removal * @pos: the type * to use as a loop cursor. * @n: another type * to use as temporary storage * @head: the head for your list. * @member: the name of the list_head within the struct. * * Iterate over list of given type from current point, safe against * removal of list entry. */ #define list_for_each_entry_safe_from(pos, n, head, member) \ for (n = list_next_entry(pos, member); \ &pos->member != (head); \ pos = n, n = list_next_entry(n, member)) /** * list_for_each_entry_safe_reverse - iterate backwards over list safe against removal * @pos: the type * to use as a loop cursor. * @n: another type * to use as temporary storage * @head: the head for your list. * @member: the name of the list_head within the struct. * * Iterate backwards over list of given type, safe against removal * of list entry. */ #define list_for_each_entry_safe_reverse(pos, n, head, member) \ for (pos = list_last_entry(head, typeof(*pos), member), \ n = list_prev_entry(pos, member); \ &pos->member != (head); \ pos = n, n = list_prev_entry(n, member)) /** * list_safe_reset_next - reset a stale list_for_each_entry_safe loop * @pos: the loop cursor used in the list_for_each_entry_safe loop * @n: temporary storage used in list_for_each_entry_safe * @member: the name of the list_head within the struct. * * list_safe_reset_next is not safe to use in general if the list may be * modified concurrently (eg. the lock is dropped in the loop body). An * exception to this is if the cursor element (pos) is pinned in the list, * and list_safe_reset_next is called after re-taking the lock and before * completing the current iteration of the loop body. */ #define list_safe_reset_next(pos, n, member) \ n = list_next_entry(pos, member) /* * 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). */ #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 !READ_ONCE(h->first); } static inline void __hlist_del(struct hlist_node *n) { struct hlist_node *next = n->next; struct hlist_node **pprev = n->pprev; WRITE_ONCE(*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; } static inline void hlist_del_init(struct hlist_node *n) { if (!hlist_unhashed(n)) { __hlist_del(n); INIT_HLIST_NODE(n); } } 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; WRITE_ONCE(h->first, n); n->pprev = &h->first; } /* 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; WRITE_ONCE(*(n->pprev), n); } static inline void hlist_add_behind(struct hlist_node *n, struct hlist_node *prev) { n->next = prev->next; prev->next = n; n->pprev = &prev->next; if (n->next) n->next->pprev = &n->next; } /* after that we'll appear to be on some hlist and hlist_del will work */ static inline void hlist_add_fake(struct hlist_node *n) { n->pprev = &n->next; } static inline bool hlist_fake(struct hlist_node *h) { return h->pprev == &h->next; } /* * Check whether the node is the only node of the head without * accessing head: */ static inline bool hlist_is_singular_node(struct hlist_node *n, struct hlist_head *h) { return !n->next && n->pprev == &h->first; } /* * Move a list from one list head to another. Fixup the pprev * reference of the first entry if it exists. */ static inline void hlist_move_list(struct hlist_head *old, struct hlist_head *new) { new->first = old->first; if (new->first) new->first->pprev = &new->first; old->first = NULL; } #define hlist_entry(ptr, type, member) container_of(ptr,type,member) #define hlist_for_each(pos, head) \ for (pos = (head)->first; pos ; pos = pos->next) #define hlist_for_each_safe(pos, n, head) \ for (pos = (head)->first; pos && ({ n = pos->next; 1; }); \ pos = n) #define hlist_entry_safe(ptr, type, member) \ ({ typeof(ptr) ____ptr = (ptr); \ ____ptr ? hlist_entry(____ptr, type, member) : NULL; \ }) /** * hlist_for_each_entry - iterate 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 hlist_node within the struct. */ #define hlist_for_each_entry(pos, head, member) \ for (pos = hlist_entry_safe((head)->first, typeof(*(pos)), member);\ pos; \ pos = hlist_entry_safe((pos)->member.next, typeof(*(pos)), member)) /** * hlist_for_each_entry_continue - iterate over a hlist continuing after current point * @pos: the type * to use as a loop cursor. * @member: the name of the hlist_node within the struct. */ #define hlist_for_each_entry_continue(pos, member) \ for (pos = hlist_entry_safe((pos)->member.next, typeof(*(pos)), member);\ pos; \ pos = hlist_entry_safe((pos)->member.next, typeof(*(pos)), member)) /** * hlist_for_each_entry_from - iterate over a hlist continuing from current point * @pos: the type * to use as a loop cursor. * @member: the name of the hlist_node within the struct. */ #define hlist_for_each_entry_from(pos, member) \ for (; pos; \ pos = hlist_entry_safe((pos)->member.next, typeof(*(pos)), member)) /** * hlist_for_each_entry_safe - iterate over list of given type safe against removal of list entry * @pos: the type * to use as a loop cursor. * @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(pos, n, head, member) \ for (pos = hlist_entry_safe((head)->first, typeof(*pos), member);\ pos && ({ n = pos->member.next; 1; }); \ pos = hlist_entry_safe(n, typeof(*pos), member)) #endif
其不是本文的重点，对双向循环链表感兴趣可见《Linux内核链表(双向)移植笔记》
2. plist.h
/* * Descending-priority-sorted double-linked list //降序优先排序的双向链表,prio越大任务优先级越小 ===> prio的值越大，在链表上越靠后 * * Based on simple lists (include/linux/list.h). * * This is a priority-sorted list of nodes; each node has a priority from INT_MIN (highest) to INT_MAX (lowest). * * Addition is O(K), removal is O(1), change of priority of a node is O(K) and K is the number of RT priority * levels used in the system. (1 <= K <= 99) * * This list is really a list of lists: * - The tier 1 list is the prio_list, different priority nodes. * - The tier 2 list is the node_list, serialized nodes. * * Simple ASCII art explanation: * * pl:prio_list (only for plist_node) * nl:node_list * HEAD| NODE(S) * | * ||------------------------------------| * ||->|pl|<->|pl|<--------------->|pl|<-| * | |10| |21| |21| |21| |40| (prio) * | | | | | | | | | | | * | | | | | | | | | | | * |->|nl|<->|nl|<->|nl|<->|nl|<->|nl|<->|nl|<-| * |-------------------------------------------| * * The nodes on the prio_list list are sorted by priority to simplify the insertion of new nodes. There are no nodes with * duplicate priorites on the list. * * The nodes on the node_list are ordered by priority and can contain entries which have the same priority. Those entries * are ordered FIFO * * Addition means: look for the prio_list node in the prio_list for the priority of the node and insert it before the node_list * entry of the next prio_list node. If it is the first node of that priority, add it to the prio_list in the right position and * insert it into the serialized node_list list * * Removal means remove it from the node_list and remove it from the prio_list if the node_list list_head is non empty. In case * of removal from the prio_list it must be checked whether other entries of the same priority are on the list or not. If there * is another entry of the same priority then this entry has to replace the removed entry on the prio_list. If the entry which * is removed is the only entry of this priority then a simple remove from both list is sufficient. * * INT_MIN is the highest priority, 0 is the medium highest, INT_MAX is lowest priority. * * No locking is done, up to the caller. */ #ifndef _LINUX_PLIST_H_ #define _LINUX_PLIST_H_ #include "list.h" /*----------I add------------*/ #include <stdio.h> #define WARN_ON(cond) \ if (cond) { \ printf("WARN: file: %s, line: %d, func: %s\n", __FILE__, __LINE__, __func__); \ } #define BUG_ON(cond) \ if (cond) { \ printf("BUG: file: %s, line: %d, func: %s\n", __FILE__, __LINE__, __func__); \ } /*------------end-----------*/ struct plist_head { struct list_head node_list; }; struct plist_node { int prio; struct list_head prio_list; struct list_head node_list; }; /** * PLIST_HEAD_INIT - static struct plist_head initializer * @head: struct plist_head variable name */ #define PLIST_HEAD_INIT(head) \ { \ .node_list = LIST_HEAD_INIT((head).node_list) \ } /** * PLIST_HEAD - declare and init plist_head * @head: name for struct plist_head variable */ #define PLIST_HEAD(head) \ struct plist_head head = PLIST_HEAD_INIT(head) /** * PLIST_NODE_INIT - static struct plist_node initializer * @node: struct plist_node variable name * @__prio: initial node priority */ #define PLIST_NODE_INIT(node, __prio) \ { \ .prio = (__prio), \ .prio_list = LIST_HEAD_INIT((node).prio_list), \ .node_list = LIST_HEAD_INIT((node).node_list), \ } /** * plist_head_init - dynamic struct plist_head initializer * @head: &struct plist_head pointer */ static inline void plist_head_init(struct plist_head *head) { INIT_LIST_HEAD(&head->node_list); } /** * plist_node_init - Dynamic struct plist_node initializer * @node: &struct plist_node pointer * @prio: initial node priority */ static inline void plist_node_init(struct plist_node *node, int prio) { node->prio = prio; INIT_LIST_HEAD(&node->prio_list); INIT_LIST_HEAD(&node->node_list); } extern void plist_add(struct plist_node *node, struct plist_head *head); extern void plist_del(struct plist_node *node, struct plist_head *head); extern void plist_requeue(struct plist_node *node, struct plist_head *head); /** * plist_for_each - iterate over the plist * @pos: the type * to use as a loop counter * @head: the head for your list */ #define plist_for_each(pos, head) \ list_for_each_entry(pos, &(head)->node_list, node_list) /** * plist_for_each_continue - continue iteration over the plist * @pos: the type * to use as a loop cursor * @head: the head for your list * * Continue to iterate over plist, continuing after the current position. */ #define plist_for_each_continue(pos, head) \ list_for_each_entry_continue(pos, &(head)->node_list, node_list) /** * plist_for_each_safe - iterate safely over a plist of given type * @pos: the type * to use as a loop counter * @n: another type * to use as temporary storage * @head: the head for your list * * Iterate over a plist of given type, safe against removal of list entry. */ #define plist_for_each_safe(pos, n, head) \ list_for_each_entry_safe(pos, n, &(head)->node_list, node_list) /** * plist_for_each_entry - iterate over list of given type * @pos: the type * to use as a loop counter * @head: the head for your list * @mem: the name of the list_head within the struct */ #define plist_for_each_entry(pos, head, mem) \ list_for_each_entry(pos, &(head)->node_list, mem.node_list) /** * plist_for_each_entry_continue - continue iteration over list of given type * @pos: the type * to use as a loop cursor * @head: the head for your list * @m: the name of the list_head within the struct * * Continue to iterate over list of given type, continuing after * the current position. */ #define plist_for_each_entry_continue(pos, head, m) \ list_for_each_entry_continue(pos, &(head)->node_list, m.node_list) /** * plist_for_each_entry_safe - iterate safely over list of given type * @pos: the type * to use as a loop counter * @n: another type * to use as temporary storage * @head: the head for your list * @m: the name of the list_head within the struct * * Iterate over list of given type, safe against removal of list entry. */ #define plist_for_each_entry_safe(pos, n, head, m) \ list_for_each_entry_safe(pos, n, &(head)->node_list, m.node_list) /** * plist_head_empty - return !0 if a plist_head is empty * @head: &struct plist_head pointer */ static inline int plist_head_empty(const struct plist_head *head) { return list_empty(&head->node_list); } /** * plist_node_empty - return !0 if plist_node is not on a list * @node: &struct plist_node pointer */ static inline int plist_node_empty(const struct plist_node *node) { return list_empty(&node->node_list); } /* All functions below assume the plist_head is not empty. */ /** * plist_first_entry - get the struct for the first entry * @head: the &struct plist_head pointer * @type: the type of the struct this is embedded in * @member: the name of the list_head within the struct */ # define plist_first_entry(head, type, member) \ container_of(plist_first(head), type, member) /** * plist_last_entry - get the struct for the last entry * @head: the &struct plist_head pointer * @type: the type of the struct this is embedded in * @member: the name of the list_head within the struct */ # define plist_last_entry(head, type, member) \ container_of(plist_last(head), type, member) /** * plist_next - get the next entry in list * @pos: the type * to cursor */ #define plist_next(pos) \ list_next_entry(pos, node_list) /** * plist_prev - get the prev entry in list * @pos: the type * to cursor */ #define plist_prev(pos) \ list_prev_entry(pos, node_list) /** * plist_first - return the first node (and thus, highest priority) * @head: the &struct plist_head pointer * * Assumes the plist is _not_ empty. */ static inline struct plist_node *plist_first(const struct plist_head *head) { return list_entry(head->node_list.next, struct plist_node, node_list); } /** * plist_last - return the last node (and thus, lowest priority) * @head: the &struct plist_head pointer * * Assumes the plist is _not_ empty. */ static inline struct plist_node *plist_last(const struct plist_head *head) { return list_entry(head->node_list.prev, struct plist_node, node_list); } #endif
3. plist.c
/* * lib/plist.c * Based on simple lists (include/linux/list.h). * * This file contains the add / del functions which are considered to * be too large to inline. See include/linux/plist.h for further * information. */ #include "plist.h" #define plist_check_head(h) do { } while (0) /** * plist_add - add @node to @head * * @node: &struct plist_node pointer * @head: &struct plist_head pointer */ void plist_add(struct plist_node *node, struct plist_head *head) { struct plist_node *first, *iter, *prev = NULL; struct list_head *node_next = &head->node_list; plist_check_head(head); WARN_ON(!plist_node_empty(node)); WARN_ON(!list_empty(&node->prio_list)); if (plist_head_empty(head)) goto ins_node; first = iter = plist_first(head); do { if (node->prio < iter->prio) { node_next = &iter->node_list; break; } prev = iter; iter = list_entry(iter->prio_list.next, struct plist_node, prio_list); } while (iter != first); if (!prev || prev->prio != node->prio) list_add_tail(&node->prio_list, &iter->prio_list); ins_node: list_add_tail(&node->node_list, node_next); plist_check_head(head); } /** * plist_del - Remove a @node from plist. * * @node: &struct plist_node pointer - entry to be removed * @head: &struct plist_head pointer - list head */ void plist_del(struct plist_node *node, struct plist_head *head) { plist_check_head(head); if (!list_empty(&node->prio_list)) { if (node->node_list.next != &head->node_list) { struct plist_node *next; next = list_entry(node->node_list.next, struct plist_node, node_list); /* add the next plist_node into prio_list */ if (list_empty(&next->prio_list)) list_add(&next->prio_list, &node->prio_list); } list_del_init(&node->prio_list); } list_del_init(&node->node_list); plist_check_head(head); } /** * plist_requeue - Requeue @node at end of same-prio entries. * * This is essentially an optimized plist_del() followed by * plist_add(). It moves an entry already in the plist to * after any other same-priority entries. * * @node: &struct plist_node pointer - entry to be moved * @head: &struct plist_head pointer - list head */ void plist_requeue(struct plist_node *node, struct plist_head *head) { struct plist_node *iter; struct list_head *node_next = &head->node_list; plist_check_head(head); BUG_ON(plist_head_empty(head)); BUG_ON(plist_node_empty(node)); if (node == plist_last(head)) return; iter = plist_next(node); if (node->prio != iter->prio) return; plist_del(node, head); plist_for_each_continue(iter, head) { if (node->prio != iter->prio) { node_next = &iter->node_list; break; } } list_add_tail(&node->node_list, node_next); plist_check_head(head); }
三、测试
1. 测试代码
#include <stdio.h> #include <stdlib.h> #include "plist.h" void plist_earse(struct plist_head *plist) { struct plist_node *pos, *n; plist_for_each_safe(pos, n, plist) { plist_del(pos, plist); printf("delete: pos->prio=%d\n", pos->prio); free(pos); } } int plist_test_first_and_last(void) { int i, first, last; struct plist_head plist; plist_head_init(&plist); for (i = 0; i < 10; i++) { struct plist_node *pnode = calloc(1, sizeof(struct plist_node)); if (!pnode) { printf("no mem.\n"); return -1; } if (i < 5) { plist_node_init(pnode, i); } else { plist_node_init(pnode, 4+(10-i)); } plist_add(pnode, &plist); } first = plist_first(&plist)->prio; last = plist_last(&plist)->prio; printf("first=%d, last=%d\n", first, last); plist_earse(&plist); return 0; } struct plist_node_m { struct plist_node pnode; int value; }; void plist_m_earse(struct plist_head *plist) { struct plist_node *pos, *n; struct plist_node_m *posm; plist_for_each_safe(pos, n, plist) { plist_del(pos, plist); posm = (struct plist_node_m *)pos; printf("delete: posm->prio=%d, posm->value=%d\n", posm->pnode.prio, posm->value); free(posm); } } int plist_repeat_add_and_order_test(void) { int i, j; struct plist_head plist; plist_head_init(&plist); for (i = 0; i < 2; i++) { for (j = 0; j < 3; j++) { struct plist_node_m *pnodem = calloc(1, sizeof(struct plist_node_m)); if (!pnodem) { printf("no mem.\n"); return -1; } pnodem->value = j; plist_node_init(&pnodem->pnode, i); plist_add(&pnodem->pnode, &plist); } } plist_m_earse(&plist); return 0; } int main() { plist_test_first_and_last(); printf("\n"); plist_repeat_add_and_order_test(); return 0; }
2. 测试结果
list_test$ ./pp first=0, last=9 delete: pos->prio=0 delete: pos->prio=1 delete: pos->prio=2 delete: pos->prio=3 delete: pos->prio=4 delete: pos->prio=5 delete: pos->prio=6 delete: pos->prio=7 delete: pos->prio=8 delete: pos->prio=9 delete: posm->prio=0, posm->value=0 delete: posm->prio=0, posm->value=1 delete: posm->prio=0, posm->value=2 delete: posm->prio=1, posm->value=0 delete: posm->prio=1, posm->value=1 delete: posm->prio=1, posm->value=2
四、总结
--待叙--