| /* SPDX-License-Identifier: GPL-2.0 */ |
| #ifndef _LINUX_RCULIST_H |
| #define _LINUX_RCULIST_H |
| |
| #ifdef __KERNEL__ |
| |
| /* |
| * RCU-protected list version |
| */ |
| #include <linux/list.h> |
| #include <linux/rcupdate.h> |
| |
| /* |
| * Why is there no list_empty_rcu()? Because list_empty() serves this |
| * purpose. The list_empty() function fetches the RCU-protected pointer |
| * and compares it to the address of the list head, but neither dereferences |
| * this pointer itself nor provides this pointer to the caller. Therefore, |
| * it is not necessary to use rcu_dereference(), so that list_empty() can |
| * be used anywhere you would want to use a list_empty_rcu(). |
| */ |
| |
| /* |
| * INIT_LIST_HEAD_RCU - Initialize a list_head visible to RCU readers |
| * @list: list to be initialized |
| * |
| * You should instead use INIT_LIST_HEAD() for normal initialization and |
| * cleanup tasks, when readers have no access to the list being initialized. |
| * However, if the list being initialized is visible to readers, you |
| * need to keep the compiler from being too mischievous. |
| */ |
| static inline void INIT_LIST_HEAD_RCU(struct list_head *list) |
| { |
| WRITE_ONCE(list->next, list); |
| WRITE_ONCE(list->prev, list); |
| } |
| |
| /* |
| * return the ->next pointer of a list_head in an rcu safe |
| * way, we must not access it directly |
| */ |
| #define list_next_rcu(list) (*((struct list_head __rcu **)(&(list)->next))) |
| |
| /** |
| * list_tail_rcu - returns the prev pointer of the head of the list |
| * @head: the head of the list |
| * |
| * Note: This should only be used with the list header, and even then |
| * only if list_del() and similar primitives are not also used on the |
| * list header. |
| */ |
| #define list_tail_rcu(head) (*((struct list_head __rcu **)(&(head)->prev))) |
| |
| /* |
| * Check during list traversal that we are within an RCU reader |
| */ |
| |
| #define check_arg_count_one(dummy) |
| |
| #ifdef CONFIG_PROVE_RCU_LIST |
| #define __list_check_rcu(dummy, cond, extra...) \ |
| ({ \ |
| check_arg_count_one(extra); \ |
| RCU_LOCKDEP_WARN(!(cond) && !rcu_read_lock_any_held(), \ |
| "RCU-list traversed in non-reader section!"); \ |
| }) |
| |
| #define __list_check_srcu(cond) \ |
| ({ \ |
| RCU_LOCKDEP_WARN(!(cond), \ |
| "RCU-list traversed without holding the required lock!");\ |
| }) |
| #else |
| #define __list_check_rcu(dummy, cond, extra...) \ |
| ({ check_arg_count_one(extra); }) |
| |
| #define __list_check_srcu(cond) ({ }) |
| #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_rcu(struct list_head *new, |
| struct list_head *prev, struct list_head *next) |
| { |
| if (!__list_add_valid(new, prev, next)) |
| return; |
| |
| new->next = next; |
| new->prev = prev; |
| rcu_assign_pointer(list_next_rcu(prev), new); |
| next->prev = new; |
| } |
| |
| /** |
| * list_add_rcu - add a new entry to rcu-protected list |
| * @new: new entry to be added |
| * @head: list head to add it after |
| * |
| * Insert a new entry after the specified head. |
| * This is good for implementing stacks. |
| * |
| * The caller must take whatever precautions are necessary |
| * (such as holding appropriate locks) to avoid racing |
| * with another list-mutation primitive, such as list_add_rcu() |
| * or list_del_rcu(), running on this same list. |
| * However, it is perfectly legal to run concurrently with |
| * the _rcu list-traversal primitives, such as |
| * list_for_each_entry_rcu(). |
| */ |
| static inline void list_add_rcu(struct list_head *new, struct list_head *head) |
| { |
| __list_add_rcu(new, head, head->next); |
| } |
| |
| /** |
| * list_add_tail_rcu - add a new entry to rcu-protected list |
| * @new: new entry to be added |
| * @head: list head to add it before |
| * |
| * Insert a new entry before the specified head. |
| * This is useful for implementing queues. |
| * |
| * The caller must take whatever precautions are necessary |
| * (such as holding appropriate locks) to avoid racing |
| * with another list-mutation primitive, such as list_add_tail_rcu() |
| * or list_del_rcu(), running on this same list. |
| * However, it is perfectly legal to run concurrently with |
| * the _rcu list-traversal primitives, such as |
| * list_for_each_entry_rcu(). |
| */ |
| static inline void list_add_tail_rcu(struct list_head *new, |
| struct list_head *head) |
| { |
| __list_add_rcu(new, head->prev, head); |
| } |
| |
| /** |
| * list_del_rcu - deletes entry from list without re-initialization |
| * @entry: the element to delete from the list. |
| * |
| * Note: list_empty() on entry does not return true after this, |
| * the entry is in an undefined state. It is useful for RCU based |
| * lockfree traversal. |
| * |
| * In particular, it means that we can not poison the forward |
| * pointers that may still be used for walking the list. |
| * |
| * The caller must take whatever precautions are necessary |
| * (such as holding appropriate locks) to avoid racing |
| * with another list-mutation primitive, such as list_del_rcu() |
| * or list_add_rcu(), running on this same list. |
| * However, it is perfectly legal to run concurrently with |
| * the _rcu list-traversal primitives, such as |
| * list_for_each_entry_rcu(). |
| * |
| * Note that the caller is not permitted to immediately free |
| * the newly deleted entry. Instead, either synchronize_rcu() |
| * or call_rcu() must be used to defer freeing until an RCU |
| * grace period has elapsed. |
| */ |
| static inline void list_del_rcu(struct list_head *entry) |
| { |
| __list_del_entry(entry); |
| entry->prev = LIST_POISON2; |
| } |
| |
| /** |
| * hlist_del_init_rcu - deletes entry from hash list with re-initialization |
| * @n: the element to delete from the hash list. |
| * |
| * Note: list_unhashed() on the node return true after this. It is |
| * useful for RCU based read lockfree traversal if the writer side |
| * must know if the list entry is still hashed or already unhashed. |
| * |
| * In particular, it means that we can not poison the forward pointers |
| * that may still be used for walking the hash list and we can only |
| * zero the pprev pointer so list_unhashed() will return true after |
| * this. |
| * |
| * The caller must take whatever precautions are necessary (such as |
| * holding appropriate locks) to avoid racing with another |
| * list-mutation primitive, such as hlist_add_head_rcu() or |
| * hlist_del_rcu(), running on this same list. However, it is |
| * perfectly legal to run concurrently with the _rcu list-traversal |
| * primitives, such as hlist_for_each_entry_rcu(). |
| */ |
| static inline void hlist_del_init_rcu(struct hlist_node *n) |
| { |
| if (!hlist_unhashed(n)) { |
| __hlist_del(n); |
| WRITE_ONCE(n->pprev, NULL); |
| } |
| } |
| |
| /** |
| * list_replace_rcu - replace old entry by new one |
| * @old : the element to be replaced |
| * @new : the new element to insert |
| * |
| * The @old entry will be replaced with the @new entry atomically. |
| * Note: @old should not be empty. |
| */ |
| static inline void list_replace_rcu(struct list_head *old, |
| struct list_head *new) |
| { |
| new->next = old->next; |
| new->prev = old->prev; |
| rcu_assign_pointer(list_next_rcu(new->prev), new); |
| new->next->prev = new; |
| old->prev = LIST_POISON2; |
| } |
| |
| /** |
| * __list_splice_init_rcu - join an RCU-protected list into an existing list. |
| * @list: the RCU-protected list to splice |
| * @prev: points to the last element of the existing list |
| * @next: points to the first element of the existing list |
| * @sync: synchronize_rcu, synchronize_rcu_expedited, ... |
| * |
| * The list pointed to by @prev and @next can be RCU-read traversed |
| * concurrently with this function. |
| * |
| * Note that this function blocks. |
| * |
| * Important note: the caller must take whatever action is necessary to prevent |
| * any other updates to the existing list. In principle, it is possible to |
| * modify the list as soon as sync() begins execution. If this sort of thing |
| * becomes necessary, an alternative version based on call_rcu() could be |
| * created. But only if -really- needed -- there is no shortage of RCU API |
| * members. |
| */ |
| static inline void __list_splice_init_rcu(struct list_head *list, |
| struct list_head *prev, |
| struct list_head *next, |
| void (*sync)(void)) |
| { |
| struct list_head *first = list->next; |
| struct list_head *last = list->prev; |
| |
| /* |
| * "first" and "last" tracking list, so initialize it. RCU readers |
| * have access to this list, so we must use INIT_LIST_HEAD_RCU() |
| * instead of INIT_LIST_HEAD(). |
| */ |
| |
| INIT_LIST_HEAD_RCU(list); |
| |
| /* |
| * At this point, the list body still points to the source list. |
| * Wait for any readers to finish using the list before splicing |
| * the list body into the new list. Any new readers will see |
| * an empty list. |
| */ |
| |
| sync(); |
| ASSERT_EXCLUSIVE_ACCESS(*first); |
| ASSERT_EXCLUSIVE_ACCESS(*last); |
| |
| /* |
| * Readers are finished with the source list, so perform splice. |
| * The order is important if the new list is global and accessible |
| * to concurrent RCU readers. Note that RCU readers are not |
| * permitted to traverse the prev pointers without excluding |
| * this function. |
| */ |
| |
| last->next = next; |
| rcu_assign_pointer(list_next_rcu(prev), first); |
| first->prev = prev; |
| next->prev = last; |
| } |
| |
| /** |
| * list_splice_init_rcu - splice an RCU-protected list into an existing list, |
| * designed for stacks. |
| * @list: the RCU-protected list to splice |
| * @head: the place in the existing list to splice the first list into |
| * @sync: synchronize_rcu, synchronize_rcu_expedited, ... |
| */ |
| static inline void list_splice_init_rcu(struct list_head *list, |
| struct list_head *head, |
| void (*sync)(void)) |
| { |
| if (!list_empty(list)) |
| __list_splice_init_rcu(list, head, head->next, sync); |
| } |
| |
| /** |
| * list_splice_tail_init_rcu - splice an RCU-protected list into an existing |
| * list, designed for queues. |
| * @list: the RCU-protected list to splice |
| * @head: the place in the existing list to splice the first list into |
| * @sync: synchronize_rcu, synchronize_rcu_expedited, ... |
| */ |
| static inline void list_splice_tail_init_rcu(struct list_head *list, |
| struct list_head *head, |
| void (*sync)(void)) |
| { |
| if (!list_empty(list)) |
| __list_splice_init_rcu(list, head->prev, head, sync); |
| } |
| |
| /** |
| * list_entry_rcu - 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. |
| * |
| * This primitive may safely run concurrently with the _rcu list-mutation |
| * primitives such as list_add_rcu() as long as it's guarded by rcu_read_lock(). |
| */ |
| #define list_entry_rcu(ptr, type, member) \ |
| container_of(READ_ONCE(ptr), type, member) |
| |
| /* |
| * Where are list_empty_rcu() and list_first_entry_rcu()? |
| * |
| * Implementing those functions following their counterparts list_empty() and |
| * list_first_entry() is not advisable because they lead to subtle race |
| * conditions as the following snippet shows: |
| * |
| * if (!list_empty_rcu(mylist)) { |
| * struct foo *bar = list_first_entry_rcu(mylist, struct foo, list_member); |
| * do_something(bar); |
| * } |
| * |
| * The list may not be empty when list_empty_rcu checks it, but it may be when |
| * list_first_entry_rcu rereads the ->next pointer. |
| * |
| * Rereading the ->next pointer is not a problem for list_empty() and |
| * list_first_entry() because they would be protected by a lock that blocks |
| * writers. |
| * |
| * See list_first_or_null_rcu for an alternative. |
| */ |
| |
| /** |
| * list_first_or_null_rcu - 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. |
| * |
| * This primitive may safely run concurrently with the _rcu list-mutation |
| * primitives such as list_add_rcu() as long as it's guarded by rcu_read_lock(). |
| */ |
| #define list_first_or_null_rcu(ptr, type, member) \ |
| ({ \ |
| struct list_head *__ptr = (ptr); \ |
| struct list_head *__next = READ_ONCE(__ptr->next); \ |
| likely(__ptr != __next) ? list_entry_rcu(__next, type, member) : NULL; \ |
| }) |
| |
| /** |
| * list_next_or_null_rcu - get the first element from a list |
| * @head: the head for the list. |
| * @ptr: the list head to take the next 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 ptr is at the end of the list, NULL is returned. |
| * |
| * This primitive may safely run concurrently with the _rcu list-mutation |
| * primitives such as list_add_rcu() as long as it's guarded by rcu_read_lock(). |
| */ |
| #define list_next_or_null_rcu(head, ptr, type, member) \ |
| ({ \ |
| struct list_head *__head = (head); \ |
| struct list_head *__ptr = (ptr); \ |
| struct list_head *__next = READ_ONCE(__ptr->next); \ |
| likely(__next != __head) ? list_entry_rcu(__next, type, \ |
| member) : NULL; \ |
| }) |
| |
| /** |
| * list_for_each_entry_rcu - iterate over rcu 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. |
| * @cond: optional lockdep expression if called from non-RCU protection. |
| * |
| * This list-traversal primitive may safely run concurrently with |
| * the _rcu list-mutation primitives such as list_add_rcu() |
| * as long as the traversal is guarded by rcu_read_lock(). |
| */ |
| #define list_for_each_entry_rcu(pos, head, member, cond...) \ |
| for (__list_check_rcu(dummy, ## cond, 0), \ |
| pos = list_entry_rcu((head)->next, typeof(*pos), member); \ |
| &pos->member != (head); \ |
| pos = list_entry_rcu(pos->member.next, typeof(*pos), member)) |
| |
| /** |
| * list_for_each_entry_srcu - iterate over rcu 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. |
| * @cond: lockdep expression for the lock required to traverse the list. |
| * |
| * This list-traversal primitive may safely run concurrently with |
| * the _rcu list-mutation primitives such as list_add_rcu() |
| * as long as the traversal is guarded by srcu_read_lock(). |
| * The lockdep expression srcu_read_lock_held() can be passed as the |
| * cond argument from read side. |
| */ |
| #define list_for_each_entry_srcu(pos, head, member, cond) \ |
| for (__list_check_srcu(cond), \ |
| pos = list_entry_rcu((head)->next, typeof(*pos), member); \ |
| &pos->member != (head); \ |
| pos = list_entry_rcu(pos->member.next, typeof(*pos), member)) |
| |
| /** |
| * list_entry_lockless - 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. |
| * |
| * This primitive may safely run concurrently with the _rcu |
| * list-mutation primitives such as list_add_rcu(), but requires some |
| * implicit RCU read-side guarding. One example is running within a special |
| * exception-time environment where preemption is disabled and where lockdep |
| * cannot be invoked. Another example is when items are added to the list, |
| * but never deleted. |
| */ |
| #define list_entry_lockless(ptr, type, member) \ |
| container_of((typeof(ptr))READ_ONCE(ptr), type, member) |
| |
| /** |
| * list_for_each_entry_lockless - iterate over rcu 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_struct within the struct. |
| * |
| * This primitive may safely run concurrently with the _rcu |
| * list-mutation primitives such as list_add_rcu(), but requires some |
| * implicit RCU read-side guarding. One example is running within a special |
| * exception-time environment where preemption is disabled and where lockdep |
| * cannot be invoked. Another example is when items are added to the list, |
| * but never deleted. |
| */ |
| #define list_for_each_entry_lockless(pos, head, member) \ |
| for (pos = list_entry_lockless((head)->next, typeof(*pos), member); \ |
| &pos->member != (head); \ |
| pos = list_entry_lockless(pos->member.next, typeof(*pos), member)) |
| |
| /** |
| * list_for_each_entry_continue_rcu - 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 which must have been in the list when the RCU read |
| * lock was taken. |
| * This would typically require either that you obtained the node from a |
| * previous walk of the list in the same RCU read-side critical section, or |
| * that you held some sort of non-RCU reference (such as a reference count) |
| * to keep the node alive *and* in the list. |
| * |
| * This iterator is similar to list_for_each_entry_from_rcu() except |
| * this starts after the given position and that one starts at the given |
| * position. |
| */ |
| #define list_for_each_entry_continue_rcu(pos, head, member) \ |
| for (pos = list_entry_rcu(pos->member.next, typeof(*pos), member); \ |
| &pos->member != (head); \ |
| pos = list_entry_rcu(pos->member.next, typeof(*pos), member)) |
| |
| /** |
| * list_for_each_entry_from_rcu - iterate over a list from current point |
| * @pos: the type * to use as a loop cursor. |
| * @head: the head for your list. |
| * @member: the name of the list_node within the struct. |
| * |
| * Iterate over the tail of a list starting from a given position, |
| * which must have been in the list when the RCU read lock was taken. |
| * This would typically require either that you obtained the node from a |
| * previous walk of the list in the same RCU read-side critical section, or |
| * that you held some sort of non-RCU reference (such as a reference count) |
| * to keep the node alive *and* in the list. |
| * |
| * This iterator is similar to list_for_each_entry_continue_rcu() except |
| * this starts from the given position and that one starts from the position |
| * after the given position. |
| */ |
| #define list_for_each_entry_from_rcu(pos, head, member) \ |
| for (; &(pos)->member != (head); \ |
| pos = list_entry_rcu(pos->member.next, typeof(*(pos)), member)) |
| |
| /** |
| * hlist_del_rcu - deletes entry from hash list without re-initialization |
| * @n: the element to delete from the hash list. |
| * |
| * Note: list_unhashed() on entry does not return true after this, |
| * the entry is in an undefined state. It is useful for RCU based |
| * lockfree traversal. |
| * |
| * In particular, it means that we can not poison the forward |
| * pointers that may still be used for walking the hash list. |
| * |
| * The caller must take whatever precautions are necessary |
| * (such as holding appropriate locks) to avoid racing |
| * with another list-mutation primitive, such as hlist_add_head_rcu() |
| * or hlist_del_rcu(), running on this same list. |
| * However, it is perfectly legal to run concurrently with |
| * the _rcu list-traversal primitives, such as |
| * hlist_for_each_entry(). |
| */ |
| static inline void hlist_del_rcu(struct hlist_node *n) |
| { |
| __hlist_del(n); |
| WRITE_ONCE(n->pprev, LIST_POISON2); |
| } |
| |
| /** |
| * hlist_replace_rcu - replace old entry by new one |
| * @old : the element to be replaced |
| * @new : the new element to insert |
| * |
| * The @old entry will be replaced with the @new entry atomically. |
| */ |
| static inline void hlist_replace_rcu(struct hlist_node *old, |
| struct hlist_node *new) |
| { |
| struct hlist_node *next = old->next; |
| |
| new->next = next; |
| WRITE_ONCE(new->pprev, old->pprev); |
| rcu_assign_pointer(*(struct hlist_node __rcu **)new->pprev, new); |
| if (next) |
| WRITE_ONCE(new->next->pprev, &new->next); |
| WRITE_ONCE(old->pprev, LIST_POISON2); |
| } |
| |
| /** |
| * hlists_swap_heads_rcu - swap the lists the hlist heads point to |
| * @left: The hlist head on the left |
| * @right: The hlist head on the right |
| * |
| * The lists start out as [@left ][node1 ... ] and |
| * [@right ][node2 ... ] |
| * The lists end up as [@left ][node2 ... ] |
| * [@right ][node1 ... ] |
| */ |
| static inline void hlists_swap_heads_rcu(struct hlist_head *left, struct hlist_head *right) |
| { |
| struct hlist_node *node1 = left->first; |
| struct hlist_node *node2 = right->first; |
| |
| rcu_assign_pointer(left->first, node2); |
| rcu_assign_pointer(right->first, node1); |
| WRITE_ONCE(node2->pprev, &left->first); |
| WRITE_ONCE(node1->pprev, &right->first); |
| } |
| |
| /* |
| * return the first or the next element in an RCU protected hlist |
| */ |
| #define hlist_first_rcu(head) (*((struct hlist_node __rcu **)(&(head)->first))) |
| #define hlist_next_rcu(node) (*((struct hlist_node __rcu **)(&(node)->next))) |
| #define hlist_pprev_rcu(node) (*((struct hlist_node __rcu **)((node)->pprev))) |
| |
| /** |
| * hlist_add_head_rcu |
| * @n: the element to add to the hash list. |
| * @h: the list to add to. |
| * |
| * Description: |
| * Adds the specified element to the specified hlist, |
| * while permitting racing traversals. |
| * |
| * The caller must take whatever precautions are necessary |
| * (such as holding appropriate locks) to avoid racing |
| * with another list-mutation primitive, such as hlist_add_head_rcu() |
| * or hlist_del_rcu(), running on this same list. |
| * However, it is perfectly legal to run concurrently with |
| * the _rcu list-traversal primitives, such as |
| * hlist_for_each_entry_rcu(), used to prevent memory-consistency |
| * problems on Alpha CPUs. Regardless of the type of CPU, the |
| * list-traversal primitive must be guarded by rcu_read_lock(). |
| */ |
| static inline void hlist_add_head_rcu(struct hlist_node *n, |
| struct hlist_head *h) |
| { |
| struct hlist_node *first = h->first; |
| |
| n->next = first; |
| WRITE_ONCE(n->pprev, &h->first); |
| rcu_assign_pointer(hlist_first_rcu(h), n); |
| if (first) |
| WRITE_ONCE(first->pprev, &n->next); |
| } |
| |
| /** |
| * hlist_add_tail_rcu |
| * @n: the element to add to the hash list. |
| * @h: the list to add to. |
| * |
| * Description: |
| * Adds the specified element to the specified hlist, |
| * while permitting racing traversals. |
| * |
| * The caller must take whatever precautions are necessary |
| * (such as holding appropriate locks) to avoid racing |
| * with another list-mutation primitive, such as hlist_add_head_rcu() |
| * or hlist_del_rcu(), running on this same list. |
| * However, it is perfectly legal to run concurrently with |
| * the _rcu list-traversal primitives, such as |
| * hlist_for_each_entry_rcu(), used to prevent memory-consistency |
| * problems on Alpha CPUs. Regardless of the type of CPU, the |
| * list-traversal primitive must be guarded by rcu_read_lock(). |
| */ |
| static inline void hlist_add_tail_rcu(struct hlist_node *n, |
| struct hlist_head *h) |
| { |
| struct hlist_node *i, *last = NULL; |
| |
| /* Note: write side code, so rcu accessors are not needed. */ |
| for (i = h->first; i; i = i->next) |
| last = i; |
| |
| if (last) { |
| n->next = last->next; |
| WRITE_ONCE(n->pprev, &last->next); |
| rcu_assign_pointer(hlist_next_rcu(last), n); |
| } else { |
| hlist_add_head_rcu(n, h); |
| } |
| } |
| |
| /** |
| * hlist_add_before_rcu |
| * @n: the new element to add to the hash list. |
| * @next: the existing element to add the new element before. |
| * |
| * Description: |
| * Adds the specified element to the specified hlist |
| * before the specified node while permitting racing traversals. |
| * |
| * The caller must take whatever precautions are necessary |
| * (such as holding appropriate locks) to avoid racing |
| * with another list-mutation primitive, such as hlist_add_head_rcu() |
| * or hlist_del_rcu(), running on this same list. |
| * However, it is perfectly legal to run concurrently with |
| * the _rcu list-traversal primitives, such as |
| * hlist_for_each_entry_rcu(), used to prevent memory-consistency |
| * problems on Alpha CPUs. |
| */ |
| static inline void hlist_add_before_rcu(struct hlist_node *n, |
| struct hlist_node *next) |
| { |
| WRITE_ONCE(n->pprev, next->pprev); |
| n->next = next; |
| rcu_assign_pointer(hlist_pprev_rcu(n), n); |
| WRITE_ONCE(next->pprev, &n->next); |
| } |
| |
| /** |
| * hlist_add_behind_rcu |
| * @n: the new element to add to the hash list. |
| * @prev: the existing element to add the new element after. |
| * |
| * Description: |
| * Adds the specified element to the specified hlist |
| * after the specified node while permitting racing traversals. |
| * |
| * The caller must take whatever precautions are necessary |
| * (such as holding appropriate locks) to avoid racing |
| * with another list-mutation primitive, such as hlist_add_head_rcu() |
| * or hlist_del_rcu(), running on this same list. |
| * However, it is perfectly legal to run concurrently with |
| * the _rcu list-traversal primitives, such as |
| * hlist_for_each_entry_rcu(), used to prevent memory-consistency |
| * problems on Alpha CPUs. |
| */ |
| static inline void hlist_add_behind_rcu(struct hlist_node *n, |
| struct hlist_node *prev) |
| { |
| n->next = prev->next; |
| WRITE_ONCE(n->pprev, &prev->next); |
| rcu_assign_pointer(hlist_next_rcu(prev), n); |
| if (n->next) |
| WRITE_ONCE(n->next->pprev, &n->next); |
| } |
| |
| #define __hlist_for_each_rcu(pos, head) \ |
| for (pos = rcu_dereference(hlist_first_rcu(head)); \ |
| pos; \ |
| pos = rcu_dereference(hlist_next_rcu(pos))) |
| |
| /** |
| * hlist_for_each_entry_rcu - iterate over rcu 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. |
| * @cond: optional lockdep expression if called from non-RCU protection. |
| * |
| * This list-traversal primitive may safely run concurrently with |
| * the _rcu list-mutation primitives such as hlist_add_head_rcu() |
| * as long as the traversal is guarded by rcu_read_lock(). |
| */ |
| #define hlist_for_each_entry_rcu(pos, head, member, cond...) \ |
| for (__list_check_rcu(dummy, ## cond, 0), \ |
| pos = hlist_entry_safe(rcu_dereference_raw(hlist_first_rcu(head)),\ |
| typeof(*(pos)), member); \ |
| pos; \ |
| pos = hlist_entry_safe(rcu_dereference_raw(hlist_next_rcu(\ |
| &(pos)->member)), typeof(*(pos)), member)) |
| |
| /** |
| * hlist_for_each_entry_srcu - iterate over rcu 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. |
| * @cond: lockdep expression for the lock required to traverse the list. |
| * |
| * This list-traversal primitive may safely run concurrently with |
| * the _rcu list-mutation primitives such as hlist_add_head_rcu() |
| * as long as the traversal is guarded by srcu_read_lock(). |
| * The lockdep expression srcu_read_lock_held() can be passed as the |
| * cond argument from read side. |
| */ |
| #define hlist_for_each_entry_srcu(pos, head, member, cond) \ |
| for (__list_check_srcu(cond), \ |
| pos = hlist_entry_safe(rcu_dereference_raw(hlist_first_rcu(head)),\ |
| typeof(*(pos)), member); \ |
| pos; \ |
| pos = hlist_entry_safe(rcu_dereference_raw(hlist_next_rcu(\ |
| &(pos)->member)), typeof(*(pos)), member)) |
| |
| /** |
| * hlist_for_each_entry_rcu_notrace - iterate over rcu list of given type (for tracing) |
| * @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. |
| * |
| * This list-traversal primitive may safely run concurrently with |
| * the _rcu list-mutation primitives such as hlist_add_head_rcu() |
| * as long as the traversal is guarded by rcu_read_lock(). |
| * |
| * This is the same as hlist_for_each_entry_rcu() except that it does |
| * not do any RCU debugging or tracing. |
| */ |
| #define hlist_for_each_entry_rcu_notrace(pos, head, member) \ |
| for (pos = hlist_entry_safe(rcu_dereference_raw_check(hlist_first_rcu(head)),\ |
| typeof(*(pos)), member); \ |
| pos; \ |
| pos = hlist_entry_safe(rcu_dereference_raw_check(hlist_next_rcu(\ |
| &(pos)->member)), typeof(*(pos)), member)) |
| |
| /** |
| * hlist_for_each_entry_rcu_bh - iterate over rcu 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. |
| * |
| * This list-traversal primitive may safely run concurrently with |
| * the _rcu list-mutation primitives such as hlist_add_head_rcu() |
| * as long as the traversal is guarded by rcu_read_lock(). |
| */ |
| #define hlist_for_each_entry_rcu_bh(pos, head, member) \ |
| for (pos = hlist_entry_safe(rcu_dereference_bh(hlist_first_rcu(head)),\ |
| typeof(*(pos)), member); \ |
| pos; \ |
| pos = hlist_entry_safe(rcu_dereference_bh(hlist_next_rcu(\ |
| &(pos)->member)), typeof(*(pos)), member)) |
| |
| /** |
| * hlist_for_each_entry_continue_rcu - 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_rcu(pos, member) \ |
| for (pos = hlist_entry_safe(rcu_dereference_raw(hlist_next_rcu( \ |
| &(pos)->member)), typeof(*(pos)), member); \ |
| pos; \ |
| pos = hlist_entry_safe(rcu_dereference_raw(hlist_next_rcu( \ |
| &(pos)->member)), typeof(*(pos)), member)) |
| |
| /** |
| * hlist_for_each_entry_continue_rcu_bh - 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_rcu_bh(pos, member) \ |
| for (pos = hlist_entry_safe(rcu_dereference_bh(hlist_next_rcu( \ |
| &(pos)->member)), typeof(*(pos)), member); \ |
| pos; \ |
| pos = hlist_entry_safe(rcu_dereference_bh(hlist_next_rcu( \ |
| &(pos)->member)), typeof(*(pos)), member)) |
| |
| /** |
| * hlist_for_each_entry_from_rcu - 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_rcu(pos, member) \ |
| for (; pos; \ |
| pos = hlist_entry_safe(rcu_dereference_raw(hlist_next_rcu( \ |
| &(pos)->member)), typeof(*(pos)), member)) |
| |
| #endif /* __KERNEL__ */ |
| #endif |