| /*! \file linuxlist.h |
| * |
| * Simple doubly linked list implementation. |
| * |
| * Some of the internal functions ("__xxx") are useful when |
| * manipulating whole llists 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. |
| */ |
| |
| #pragma once |
| |
| /*! \defgroup linuxlist Simple doubly linked list implementation |
| * @{ |
| * \file linuxlist.h */ |
| |
| #include <stddef.h> |
| #include <stdbool.h> |
| |
| #ifndef inline |
| #define inline __inline__ |
| #endif |
| |
| static inline void prefetch(const void *x) {;} |
| |
| /*! Cast a member of a structure out to the containing structure. |
| * \param[in] ptr the pointer to the member. |
| * \param[in] type the type of the container struct this is embedded in. |
| * \param[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) );}) |
| |
| |
| /*! |
| * These are non-NULL pointers that will result in page faults |
| * under normal circumstances, used to verify that nobody uses |
| * non-initialized llist entries. |
| */ |
| #define LLIST_POISON1 ((void *) 0x00100100) |
| #define LLIST_POISON2 ((void *) 0x00200200) |
| |
| /*! (double) linked list header structure */ |
| struct llist_head { |
| /*! Pointer to next and previous item */ |
| struct llist_head *next, *prev; |
| }; |
| |
| /*! Define a new llist_head pointing to a given llist_head. |
| * \param[in] name another llist_head to be pointed. |
| */ |
| #define LLIST_HEAD_INIT(name) { &(name), &(name) } |
| |
| /*! Define a statically-initialized variable of type llist_head. |
| * \param[in] name variable (symbol) name. |
| */ |
| #define LLIST_HEAD(name) \ |
| struct llist_head name = LLIST_HEAD_INIT(name) |
| |
| /*! Initialize a llist_head to point back to itself. |
| * \param[in] ptr llist_head to be initialized. |
| */ |
| #define INIT_LLIST_HEAD(ptr) do { \ |
| (ptr)->next = (ptr); (ptr)->prev = (ptr); \ |
| } while (0) |
| |
| /* |
| * Insert a new entry between two known consecutive entries. |
| * |
| * This is only for internal llist manipulation where we know |
| * the prev/next entries already! |
| */ |
| static inline void __llist_add(struct llist_head *_new, |
| struct llist_head *prev, |
| struct llist_head *next) |
| { |
| next->prev = _new; |
| _new->next = next; |
| _new->prev = prev; |
| prev->next = _new; |
| } |
| |
| /*! Add a new entry into a linked list (at head). |
| * \param _new the entry to be added. |
| * \param head llist_head to prepend the element to. |
| * |
| * Insert a new entry after the specified head. |
| * This is good for implementing stacks. |
| */ |
| static inline void llist_add(struct llist_head *_new, struct llist_head *head) |
| { |
| __llist_add(_new, head, head->next); |
| } |
| |
| /*! Add a new entry into a linked list (at tail). |
| * \param _new the entry to be added. |
| * \param head llist_head to append the element to. |
| * |
| * Insert a new entry before the specified head. |
| * This is useful for implementing queues. |
| */ |
| static inline void llist_add_tail(struct llist_head *_new, struct llist_head *head) |
| { |
| __llist_add(_new, head->prev, head); |
| } |
| |
| /* |
| * Delete a llist entry by making the prev/next entries |
| * point to each other. |
| * |
| * This is only for internal llist manipulation where we know |
| * the prev/next entries already! |
| */ |
| static inline void __llist_del(struct llist_head * prev, struct llist_head * next) |
| { |
| next->prev = prev; |
| prev->next = next; |
| } |
| |
| /*! Delete a single entry from a linked list. |
| * \param entry the element to delete. |
| * |
| * Note: llist_empty on entry does not return true after this, the entry is |
| * in an undefined state. |
| */ |
| static inline void llist_del(struct llist_head *entry) |
| { |
| __llist_del(entry->prev, entry->next); |
| entry->next = (struct llist_head *)LLIST_POISON1; |
| entry->prev = (struct llist_head *)LLIST_POISON2; |
| } |
| |
| /*! Delete a single entry from a linked list and reinitialize it. |
| * \param entry the element to delete and reinitialize. |
| */ |
| static inline void llist_del_init(struct llist_head *entry) |
| { |
| __llist_del(entry->prev, entry->next); |
| INIT_LLIST_HEAD(entry); |
| } |
| |
| /*! Delete from one llist and add as another's head. |
| * \param llist the entry to move. |
| * \param head the head that will precede our entry. |
| */ |
| static inline void llist_move(struct llist_head *llist, struct llist_head *head) |
| { |
| __llist_del(llist->prev, llist->next); |
| llist_add(llist, head); |
| } |
| |
| /*! Delete from one llist and add as another's tail. |
| * \param llist the entry to move. |
| * \param head the head that will follow our entry. |
| */ |
| static inline void llist_move_tail(struct llist_head *llist, |
| struct llist_head *head) |
| { |
| __llist_del(llist->prev, llist->next); |
| llist_add_tail(llist, head); |
| } |
| |
| /*! Test whether a linked list is empty. |
| * \param[in] head the llist to test. |
| * \returns 1 if the list is empty, 0 otherwise. |
| */ |
| static inline int llist_empty(const struct llist_head *head) |
| { |
| return head->next == head; |
| } |
| |
| static inline void __llist_splice(struct llist_head *llist, |
| struct llist_head *head) |
| { |
| struct llist_head *first = llist->next; |
| struct llist_head *last = llist->prev; |
| struct llist_head *at = head->next; |
| |
| first->prev = head; |
| head->next = first; |
| |
| last->next = at; |
| at->prev = last; |
| } |
| |
| /*! Join two linked lists. |
| * \param llist the new linked list to add. |
| * \param head the place to add llist within the other list. |
| */ |
| static inline void llist_splice(struct llist_head *llist, struct llist_head *head) |
| { |
| if (!llist_empty(llist)) |
| __llist_splice(llist, head); |
| } |
| |
| /*! Join two llists and reinitialise the emptied llist. |
| * \param llist the new linked list to add. |
| * \param head the place to add it within the first llist. |
| * |
| * The llist is reinitialised. |
| */ |
| static inline void llist_splice_init(struct llist_head *llist, |
| struct llist_head *head) |
| { |
| if (!llist_empty(llist)) { |
| __llist_splice(llist, head); |
| INIT_LLIST_HEAD(llist); |
| } |
| } |
| |
| /*! Get the struct containing this list entry. |
| * \param ptr the llist_head pointer. |
| * \param type the type of the struct this is embedded in. |
| * \param member the name of the llist_head within the struct. |
| */ |
| #define llist_entry(ptr, type, member) \ |
| container_of(ptr, type, member) |
| |
| /*! Get the first element from a linked list. |
| * \param ptr the list head to take the element from. |
| * \param type the type of the struct this is embedded in. |
| * \param member the name of the list_head within the struct. |
| * |
| * Note, that list is expected to be not empty. |
| */ |
| #define llist_first_entry(ptr, type, member) \ |
| llist_entry((ptr)->next, type, member) |
| |
| /*! Get the last element from a list. |
| * \param ptr the list head to take the element from. |
| * \param type the type of the struct this is embedded in. |
| * \param member the name of the llist_head within the struct. |
| * |
| * Note, that list is expected to be not empty. |
| */ |
| #define llist_last_entry(ptr, type, member) \ |
| llist_entry((ptr)->prev, type, member) |
| |
| /*! Get the first element from a list, or NULL. |
| * \param ptr the list head to take the element from. |
| * \param type the type of the struct this is embedded in. |
| * \param member the name of the list_head within the struct. |
| * |
| * Note that if the list is empty, it returns NULL. |
| */ |
| #define llist_first_entry_or_null(ptr, type, member) \ |
| (!llist_empty(ptr) ? llist_first_entry(ptr, type, member) : NULL) |
| |
| /*! Iterate over a linked list. |
| * \param pos the llist_head to use as a loop counter. |
| * \param head the head of the list over which to iterate. |
| */ |
| #define llist_for_each(pos, head) \ |
| for (pos = (head)->next, prefetch(pos->next); pos != (head); \ |
| pos = pos->next, prefetch(pos->next)) |
| |
| /*! Iterate over a linked list (no prefetch). |
| * \param pos the llist_head to use as a loop counter. |
| * \param head the head of the list over which to iterate. |
| * |
| * This variant differs from llist_for_each() in that it's the |
| * simplest possible llist iteration code, no prefetching is done. |
| * Use this for code that knows the llist to be very short (empty |
| * or 1 entry) most of the time. |
| */ |
| #define __llist_for_each(pos, head) \ |
| for (pos = (head)->next; pos != (head); pos = pos->next) |
| |
| /*! Iterate over a linked list backwards. |
| * \param pos the llist_head to use as a loop counter. |
| * \param head the head of the list over which to iterate. |
| */ |
| #define llist_for_each_prev(pos, head) \ |
| for (pos = (head)->prev, prefetch(pos->prev); pos != (head); \ |
| pos = pos->prev, prefetch(pos->prev)) |
| |
| /*! Iterate over a linked list, safe against removal of llist entry. |
| * \param pos the llist_head to use as a loop counter. |
| * \param n another llist_head to use as temporary storage. |
| * \param head the head of the list over which to iterate. |
| */ |
| #define llist_for_each_safe(pos, n, head) \ |
| for (pos = (head)->next, n = pos->next; pos != (head); \ |
| pos = n, n = pos->next) |
| |
| /*! Iterate over a linked list of a given type. |
| * \param pos the 'type *' to use as a loop counter. |
| * \param head the head of the list over which to iterate. |
| * \param member the name of the llist_head within the struct pos. |
| */ |
| #define llist_for_each_entry(pos, head, member) \ |
| for (pos = llist_entry((head)->next, typeof(*pos), member), \ |
| prefetch(pos->member.next); \ |
| &pos->member != (head); \ |
| pos = llist_entry(pos->member.next, typeof(*pos), member), \ |
| prefetch(pos->member.next)) |
| |
| /*! Iterate backwards over a linked list of a given type. |
| * \param pos the 'type *' to use as a loop counter. |
| * \param head the head of the list over which to iterate. |
| * \param member the name of the llist_head within the struct pos. |
| */ |
| #define llist_for_each_entry_reverse(pos, head, member) \ |
| for (pos = llist_entry((head)->prev, typeof(*pos), member), \ |
| prefetch(pos->member.prev); \ |
| &pos->member != (head); \ |
| pos = llist_entry(pos->member.prev, typeof(*pos), member), \ |
| prefetch(pos->member.prev)) |
| |
| /*! Iterate over a linked list of a given type, |
| * continuing after an existing point. |
| * \param pos the 'type *' to use as a loop counter. |
| * \param head the head of the list over which to iterate. |
| * \param member the name of the llist_head within the struct pos. |
| */ |
| #define llist_for_each_entry_continue(pos, head, member) \ |
| for (pos = llist_entry(pos->member.next, typeof(*pos), member), \ |
| prefetch(pos->member.next); \ |
| &pos->member != (head); \ |
| pos = llist_entry(pos->member.next, typeof(*pos), member), \ |
| prefetch(pos->member.next)) |
| |
| /*! Iterate over llist of given type, safe against removal of |
| * non-consecutive(!) llist entries. |
| * \param pos the 'type *' to use as a loop counter. |
| * \param n another 'type *' to use as temporary storage. |
| * \param head the head of the list over which to iterate. |
| * \param member the name of the llist_head within the struct pos. |
| */ |
| #define llist_for_each_entry_safe(pos, n, head, member) \ |
| for (pos = llist_entry((head)->next, typeof(*pos), member), \ |
| n = llist_entry(pos->member.next, typeof(*pos), member); \ |
| &pos->member != (head); \ |
| pos = n, n = llist_entry(n->member.next, typeof(*n), member)) |
| |
| /*! Iterate over an rcu-protected llist. |
| * \param pos the llist_head to use as a loop counter. |
| * \param head the head of the list over which to iterate. |
| */ |
| #define llist_for_each_rcu(pos, head) \ |
| for (pos = (head)->next, prefetch(pos->next); pos != (head); \ |
| pos = pos->next, ({ smp_read_barrier_depends(); 0;}), prefetch(pos->next)) |
| |
| #define __llist_for_each_rcu(pos, head) \ |
| for (pos = (head)->next; pos != (head); \ |
| pos = pos->next, ({ smp_read_barrier_depends(); 0;})) |
| |
| /*! Iterate over an rcu-protected llist, safe against removal of llist entry. |
| * \param pos the llist_head to use as a loop counter. |
| * \param n another llist_head to use as temporary storage. |
| * \param head the head of the list over which to iterate. |
| */ |
| #define llist_for_each_safe_rcu(pos, n, head) \ |
| for (pos = (head)->next, n = pos->next; pos != (head); \ |
| pos = n, ({ smp_read_barrier_depends(); 0;}), n = pos->next) |
| |
| /*! Iterate over an rcu-protected llist of a given type. |
| * \param pos the 'type *' to use as a loop counter. |
| * \param head the head of the list over which to iterate. |
| * \param member the name of the llist_struct within the struct. |
| */ |
| #define llist_for_each_entry_rcu(pos, head, member) \ |
| for (pos = llist_entry((head)->next, typeof(*pos), member), \ |
| prefetch(pos->member.next); \ |
| &pos->member != (head); \ |
| pos = llist_entry(pos->member.next, typeof(*pos), member), \ |
| ({ smp_read_barrier_depends(); 0;}), \ |
| prefetch(pos->member.next)) |
| |
| |
| /*! Iterate over an rcu-protected llist, continuing after existing point. |
| * \param pos the llist_head to use as a loop counter. |
| * \param head the head of the list over which to iterate. |
| */ |
| #define llist_for_each_continue_rcu(pos, head) \ |
| for ((pos) = (pos)->next, prefetch((pos)->next); (pos) != (head); \ |
| (pos) = (pos)->next, ({ smp_read_barrier_depends(); 0;}), prefetch((pos)->next)) |
| |
| /*! Count number of llist items by iterating. |
| * \param head the llist head to count items of. |
| * \returns Number of items. |
| * |
| * This function is not efficient, mostly useful for small lists and non time |
| * critical cases like unit tests. |
| */ |
| static inline unsigned int llist_count(const struct llist_head *head) |
| { |
| struct llist_head *entry; |
| unsigned int i = 0; |
| llist_for_each(entry, head) |
| i++; |
| return i; |
| } |
| |
| |
| |
| /*! 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; |
| } |
| |
| #define READ_ONCE(x) x |
| #define WRITE_ONCE(a, b) a = b |
| |
| /*! Has node been removed from list and reinitialized?. |
| * \param[in] h: Node to be checked |
| * \return 1 if node is unhashed; 0 if not |
| * |
| * Not that not all removal functions will leave a node in unhashed |
| * state. For example, hlist_nulls_del_init_rcu() does leave the |
| * node in unhashed state, but hlist_nulls_del() does not. |
| */ |
| static inline int hlist_unhashed(const struct hlist_node *h) |
| { |
| return !h->pprev; |
| } |
| |
| /*! Version of hlist_unhashed for lockless use. |
| * \param[in] n Node to be checked |
| * \return 1 if node is unhashed; 0 if not |
| * |
| * This variant of hlist_unhashed() must be used in lockless contexts |
| * to avoid potential load-tearing. The READ_ONCE() is paired with the |
| * various WRITE_ONCE() in hlist helpers that are defined below. |
| */ |
| static inline int hlist_unhashed_lockless(const struct hlist_node *h) |
| { |
| return !READ_ONCE(h->pprev); |
| } |
| |
| /*!Is the specified hlist_head structure an empty hlist?. |
| * \param[in] h Structure to check. |
| * \return 1 if hlist is empty; 0 if not |
| */ |
| 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) |
| WRITE_ONCE(next->pprev, pprev); |
| } |
| |
| /*! Delete the specified hlist_node from its list. |
| * \param[in] n: Node to delete. |
| * |
| * Note that this function leaves the node in hashed state. Use |
| * hlist_del_init() or similar instead to unhash @n. |
| */ |
| static inline void hlist_del(struct hlist_node *n) |
| { |
| __hlist_del(n); |
| n->next = (struct hlist_node *)LLIST_POISON1; |
| n->pprev = (struct hlist_node **)LLIST_POISON2; |
| } |
| |
| /*! Delete the specified hlist_node from its list and initialize. |
| * \param[in] n Node to delete. |
| * |
| * Note that this function leaves the node in unhashed state. |
| */ |
| static inline void hlist_del_init(struct hlist_node *n) |
| { |
| if (!hlist_unhashed(n)) { |
| __hlist_del(n); |
| INIT_HLIST_NODE(n); |
| } |
| } |
| |
| /*! add a new entry at the beginning of the hlist. |
| * \param[in] n new entry to be added |
| * \param[in] h hlist head to add it after |
| * |
| * Insert a new entry after the specified head. |
| * This is good for implementing stacks. |
| */ |
| static inline void hlist_add_head(struct hlist_node *n, struct hlist_head *h) |
| { |
| struct hlist_node *first = h->first; |
| WRITE_ONCE(n->next, first); |
| if (first) |
| WRITE_ONCE(first->pprev, &n->next); |
| WRITE_ONCE(h->first, n); |
| WRITE_ONCE(n->pprev, &h->first); |
| } |
| |
| /*! add a new entry before the one specified. |
| * @n: new entry to be added |
| * @next: hlist node to add it before, which must be non-NULL |
| */ |
| static inline void hlist_add_before(struct hlist_node *n, |
| struct hlist_node *next) |
| { |
| WRITE_ONCE(n->pprev, next->pprev); |
| WRITE_ONCE(n->next, next); |
| WRITE_ONCE(next->pprev, &n->next); |
| WRITE_ONCE(*(n->pprev), n); |
| } |
| |
| /*! add a new entry after the one specified |
| * \param[in] n new entry to be added |
| * \param[in] prev hlist node to add it after, which must be non-NULL |
| */ |
| static inline void hlist_add_behind(struct hlist_node *n, |
| struct hlist_node *prev) |
| { |
| WRITE_ONCE(n->next, prev->next); |
| WRITE_ONCE(prev->next, n); |
| WRITE_ONCE(n->pprev, &prev->next); |
| |
| if (n->next) |
| WRITE_ONCE(n->next->pprev, &n->next); |
| } |
| |
| /*! create a fake hlist consisting of a single headless node. |
| * \param[in] n Node to make a fake list out of |
| * |
| * This makes @n appear to be its own predecessor on a headless hlist. |
| * The point of this is to allow things like hlist_del() to work correctly |
| * in cases where there is no list. |
| */ |
| static inline void hlist_add_fake(struct hlist_node *n) |
| { |
| n->pprev = &n->next; |
| } |
| |
| /*! Is this node a fake hlist?. |
| * \param[in] h Node to check for being a self-referential fake hlist. |
| */ |
| static inline bool hlist_fake(struct hlist_node *h) |
| { |
| return h->pprev == &h->next; |
| } |
| |
| /*!is node the only element of the specified hlist?. |
| * \param[in] n Node to check for singularity. |
| * \param[in] h Header for potentially singular list. |
| * |
| * Check whether the node is the only node of the head without |
| * accessing head, thus avoiding unnecessary cache misses. |
| */ |
| static inline bool |
| hlist_is_singular_node(struct hlist_node *n, struct hlist_head *h) |
| { |
| return !n->next && n->pprev == &h->first; |
| } |
| |
| /*! Move an hlist. |
| * \param[in] old hlist_head for old list. |
| * \param[in] new hlist_head for new list. |
| * |
| * 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; \ |
| }) |
| |
| /*! iterate over list of given type. |
| * \param[out] pos the type * to use as a loop cursor. |
| * \param[in] head the head for your list. |
| * \param[in] 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)) |
| |
| /*! iterate over a hlist continuing after current point. |
| * \param[out] pos the type * to use as a loop cursor. |
| * \param[in] 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)) |
| |
| /*! iterate over a hlist continuing from current point. |
| * \param[out] pos the type * to use as a loop cursor. |
| * \param[in] 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. |
| * \param[out] pos the type * to use as a loop cursor. |
| * \param[out] n a &struct hlist_node to use as temporary storage |
| * \param[in] head the head for your list. |
| * \param[in] 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)) |
| |
| |
| /*! |
| * @} |
| */ |