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Diffstat (limited to 'include/linux/rculist.h')
| -rw-r--r-- | include/linux/rculist.h | 805 |
1 files changed, 805 insertions, 0 deletions
diff --git a/include/linux/rculist.h b/include/linux/rculist.h new file mode 100644 index 000000000..d29740be4 --- /dev/null +++ b/include/linux/rculist.h @@ -0,0 +1,805 @@ +/* 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> + +/* + * 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()? + * + * They do not exist because they would lead to subtle race conditions: + * + * if (!list_empty_rcu(mylist)) { + * struct foo *bar = list_first_entry_rcu(mylist, struct foo, list_member); + * do_something(bar); + * } + * + * The list might be non-empty when list_empty_rcu() checks it, but it + * might have become empty by the time that list_first_entry_rcu() rereads + * the ->next pointer, which would result in a SEGV. + * + * When not using RCU, it is OK for list_first_entry() to re-read that + * pointer because both functions should be protected by some lock that + * blocks writers. + * + * When using RCU, list_empty() uses READ_ONCE() to fetch the + * RCU-protected ->next pointer and then compares it to the address of the + * list head. However, it neither dereferences this pointer nor provides + * this pointer to its caller. Thus, READ_ONCE() suffices (that is, + * rcu_dereference() is not needed), which means that list_empty() can be + * used anywhere you would want to use list_empty_rcu(). Just don't + * expect anything useful to happen if you do a subsequent lockless + * call to list_first_entry_rcu()!!! + * + * 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 |