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#include <linux/container_of.h>#include <linux/types.h>#include <linux/stddef.h>#include <linux/poison.h>#include <linux/const.h>
#include <asm/barrier.h>
/* * Circular 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. */
/** * LIST_HEAD_INIT - initialize a &struct list_head's links to point to itself * @name: name of the list_head */#define LIST_HEAD_INIT(name) { &(name), &(name) }
/** * LIST_HEAD - definition of a &struct list_head with initialization values * @name: name of the list_head */#define LIST_HEAD(name) \ struct list_head name = LIST_HEAD_INIT(name)
/** * LIST_HEAD_GUARDED - define a &struct list_head annotated with __guarded_by() * @name: name of the list_head * @lock: lock protecting the list */#define LIST_HEAD_GUARDED(name, lock) \ __guarded_by(&(lock)) LIST_HEAD(name)
/** * INIT_LIST_HEAD - Initialize a list_head structure * @list: list_head structure to be initialized. * * Initializes the list_head to point to itself. If it is a list header, * the result is an empty list. */static inline void INIT_LIST_HEAD(struct list_head *list){ WRITE_ONCE(list->next, list); WRITE_ONCE(list->prev, list);}
#ifdef CONFIG_LIST_HARDENED
#ifdef CONFIG_DEBUG_LIST# define __list_valid_slowpath#else# define __list_valid_slowpath __cold __preserve_most#endif
/* * Performs the full set of list corruption checks before __list_add(). * On list corruption reports a warning, and returns false. */bool __list_valid_slowpath __list_add_valid_or_report(struct list_head *new, struct list_head *prev, struct list_head *next);
/* * Performs list corruption checks before __list_add(). Returns false if a * corruption is detected, true otherwise. * * With CONFIG_LIST_HARDENED only, performs minimal list integrity checking * inline to catch non-faulting corruptions, and only if a corruption is * detected calls the reporting function __list_add_valid_or_report(). */static __always_inline bool __list_add_valid(struct list_head *new, struct list_head *prev, struct list_head *next){ bool ret = true;
if (!IS_ENABLED(CONFIG_DEBUG_LIST)) { /* * With the hardening version, elide checking if next and prev * are NULL, since the immediate dereference of them below would * result in a fault if NULL. * * With the reduced set of checks, we can afford to inline the * checks, which also gives the compiler a chance to elide some * of them completely if they can be proven at compile-time. If * one of the pre-conditions does not hold, the slow-path will * show a report which pre-condition failed. */ if (likely(next->prev == prev && prev->next == next && new != prev && new != next)) return true; ret = false; }
ret &= __list_add_valid_or_report(new, prev, next); return ret;}
/* * Performs the full set of list corruption checks before __list_del_entry(). * On list corruption reports a warning, and returns false. */bool __list_valid_slowpath __list_del_entry_valid_or_report(struct list_head *entry);
/* * Performs list corruption checks before __list_del_entry(). Returns false if a * corruption is detected, true otherwise. * * With CONFIG_LIST_HARDENED only, performs minimal list integrity checking * inline to catch non-faulting corruptions, and only if a corruption is * detected calls the reporting function __list_del_entry_valid_or_report(). */static __always_inline bool __list_del_entry_valid(struct list_head *entry){ bool ret = true;
if (!IS_ENABLED(CONFIG_DEBUG_LIST)) { struct list_head *prev = entry->prev; struct list_head *next = entry->next;
/* * With the hardening version, elide checking if next and prev * are NULL, LIST_POISON1 or LIST_POISON2, since the immediate * dereference of them below would result in a fault. */ if (likely(prev->next == entry && next->prev == entry)) return true; ret = false; }
ret &= __list_del_entry_valid_or_report(entry); return ret;}#elsestatic 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! * * Must be inlined to ensure it can be safely called * with initdata arguments. */static __always_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. * * Must be inlined to ensure it can be safely called * with initdata arguments. */static __always_inline void list_add(struct list_head *new, struct list_head *head){ __list_add(new, head, head->next);}
/** * list_add_tail - add a new entry * @new: new entry to be added * @head: list head to add it before * * Insert a new entry before the specified head. * This is useful for implementing queues. */static inline void list_add_tail(struct list_head *new, struct list_head *head){ __list_add(new, head->prev, head);}
/** * list_add_tail_release - add a new entry with release barrier * @new: new entry to be added * @head: list head to add it before * * Insert a new entry before the specified head, using a release barrier to set * the ->next pointer that points to it. This is useful for implementing * queues, in particular one that the elements will be walked through forwards * locklessly. */static inline void list_add_tail_release(struct list_head *new, struct list_head *head){ struct list_head *prev = head->prev;
if (__list_add_valid(new, prev, head)) { new->next = head; new->prev = prev; head->prev = new; smp_store_release(&prev->next, new); }}
/* * 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; 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;}
static inline void __list_del_entry(struct list_head *entry){ if (!__list_del_entry_valid(entry)) return;
__list_del(entry->prev, entry->next);}
/** * list_del - deletes entry from list. * @entry: the element to delete from the list. * Note: list_empty() on entry does not return true after this, the entry is * in an undefined state. */static inline void list_del(struct list_head *entry){ __list_del_entry(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;}
/** * list_replace_init - replace old entry by new one and initialize the old 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_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_is_head - tests whether @list is the list @head * @list: the entry to test * @head: the head of the list */static inline int list_is_head(const struct list_head *list, const struct list_head *head){ return list == head;}
/** * list_empty - tests whether a list is empty * @head: the list to test. */static inline int list_empty(const struct list_head *head){ return READ_ONCE(head->next) == head;}
/** * list_del_init_careful - deletes entry from list and reinitialize it. * @entry: the element to delete from the list. * * This is the same as list_del_init(), except designed to be used * together with list_empty_careful() in a way to guarantee ordering * of other memory operations. * * Any memory operations done before a list_del_init_careful() are * guaranteed to be visible after a list_empty_careful() test. */static inline void list_del_init_careful(struct list_head *entry){ __list_del_entry(entry); WRITE_ONCE(entry->prev, entry); smp_store_release(&entry->next, entry);}
/** * 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) __context_unsafe(/* intentional lockless access to @head */){ struct list_head *next = smp_load_acquire(&head->next); return list_is_head(next, head) && (next == READ_ONCE(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) && !list_is_head(entry, head) && (entry != head->next)) return; if (list_is_head(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_first_entry_or_null_acquire - get the first element from a list with barrier * @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_acquire(ptr, type, member) ({ \ struct list_head *head__ = (ptr); \ struct list_head *pos__ = smp_load_acquire(&head__->next); \ pos__ != head__ ? list_entry(pos__, type, member) : NULL; \})
/** * list_last_entry_or_null - 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 if the list is empty, it returns NULL. */#define list_last_entry_or_null(ptr, type, member) ({ \ struct list_head *head__ = (ptr); \ struct list_head *pos__ = READ_ONCE(head__->prev); \ 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_next_entry_circular - get the next element in list * @pos: the type * to cursor. * @head: the list head to take the element from. * @member: the name of the list_head within the struct. * * Wraparound if pos is the last element (return the first element). * Note, that list is expected to be not empty. */#define list_next_entry_circular(pos, head, member) \ (list_is_last(&(pos)->member, head) ? \ list_first_entry(head, typeof(*(pos)), member) : list_next_entry(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_prev_entry_circular - get the prev element in list * @pos: the type * to cursor. * @head: the list head to take the element from. * @member: the name of the list_head within the struct. * * Wraparound if pos is the first element (return the last element). * Note, that list is expected to be not empty. */#define list_prev_entry_circular(pos, head, member) \ (list_is_first(&(pos)->member, head) ? \ list_last_entry(head, typeof(*(pos)), member) : list_prev_entry(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. */#define list_for_each(pos, head) \ for (pos = (head)->next; !list_is_head(pos, (head)); pos = pos->next)
/** * list_for_each_continue - continue iteration over a list * @pos: the &struct list_head to use as a loop cursor. * @head: the head for your list. * * Continue to iterate over a list, continuing after the current position. */#define list_for_each_continue(pos, head) \ for (pos = pos->next; !list_is_head(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; !list_is_head(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; \ !list_is_head(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; \ !list_is_head(pos, (head)); \ pos = n, n = pos->prev)
/** * list_count_nodes - count nodes in the list * @head: the head for your list. */static inline size_t list_count_nodes(struct list_head *head){ struct list_head *pos; size_t count = 0;
list_for_each(pos, head) count++;
return count;}
/** * list_entry_is_head - test if the entry points to the head of the list * @pos: the type * to cursor * @head: the head for your list. * @member: the name of the list_head within the struct. */#define list_entry_is_head(pos, head, member) \ list_is_head(&pos->member, (head))
/** * 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. */#define list_for_each_entry(pos, head, member) \ for (pos = list_first_entry(head, typeof(*pos), member); \ !list_entry_is_head(pos, head, member); \ 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); \ !list_entry_is_head(pos, head, member); \ 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); \ !list_entry_is_head(pos, head, member); \ 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); \ !list_entry_is_head(pos, head, member); \ 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 (; !list_entry_is_head(pos, head, member); \ 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 (; !list_entry_is_head(pos, head, member); \ 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); \ !list_entry_is_head(pos, head, member); \ 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); \ !list_entry_is_head(pos, head, member); \ 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); \ !list_entry_is_head(pos, head, member); \ 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); \ !list_entry_is_head(pos, head, member); \ 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;}
/** * hlist_unhashed - Has node been removed from list and reinitialized? * @h: Node to be checked * * 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;}
/** * hlist_unhashed_lockless - Version of hlist_unhashed for lockless use * @h: Node to be checked * * 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);}
/** * hlist_empty - Is the specified hlist_head structure an empty hlist? * @h: Structure to check. */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);}
/** * hlist_del - Delete the specified hlist_node from its list * @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 = LIST_POISON1; n->pprev = LIST_POISON2;}
/** * hlist_del_init - Delete the specified hlist_node from its list and initialize * @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); }}
/** * hlist_add_head - add a new entry at the beginning of the hlist * @n: new entry to be added * @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);}
/** * hlist_add_before - 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);}
/** * hlist_add_behind - add a new entry after the one specified * @n: new entry to be added * @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);}
/** * hlist_add_fake - create a fake hlist consisting of a single headless node * @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;}
/** * hlist_fake: Is this node a fake hlist? * @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;}
/** * hlist_is_singular_node - is node the only element of the specified hlist? * @n: Node to check for singularity. * @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 boolhlist_is_singular_node(struct hlist_node *n, struct hlist_head *h){ return !n->next && n->pprev == &h->first;}
/** * hlist_move_list - Move an hlist * @old: hlist_head for old list. * @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;}
/** * hlist_splice_init() - move all entries from one list to another * @from: hlist_head from which entries will be moved * @last: last entry on the @from list * @to: hlist_head to which entries will be moved * * @to can be empty, @from must contain at least @last. */static inline void hlist_splice_init(struct hlist_head *from, struct hlist_node *last, struct hlist_head *to){ if (to->first) to->first->pprev = &last->next; last->next = to->first; to->first = from->first; from->first->pprev = &to->first; from->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: a &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))
/** * hlist_count_nodes - count nodes in the hlist * @head: the head for your hlist. */static inline size_t hlist_count_nodes(struct hlist_head *head){ struct hlist_node *pos; size_t count = 0;
hlist_for_each(pos, head) count++;
return count;}
#endif