| 1 | /* SPDX-License-Identifier: GPL-2.0 */ |
| 2 | #ifndef _LINUX_RCULIST_BL_H |
| 3 | #define _LINUX_RCULIST_BL_H |
| 4 | |
| 5 | /* |
| 6 | * RCU-protected bl list version. See include/linux/list_bl.h. |
| 7 | */ |
| 8 | #include <linux/list_bl.h> |
| 9 | #include <linux/rcupdate.h> |
| 10 | |
| 11 | static inline void hlist_bl_set_first_rcu(struct hlist_bl_head *h, |
| 12 | struct hlist_bl_node *n) |
| 13 | { |
| 14 | LIST_BL_BUG_ON((unsigned long)n & LIST_BL_LOCKMASK); |
| 15 | LIST_BL_BUG_ON(((unsigned long)h->first & LIST_BL_LOCKMASK) != |
| 16 | LIST_BL_LOCKMASK); |
| 17 | rcu_assign_pointer(h->first, |
| 18 | (struct hlist_bl_node *)((unsigned long)n | LIST_BL_LOCKMASK)); |
| 19 | } |
| 20 | |
| 21 | static inline struct hlist_bl_node *hlist_bl_first_rcu(struct hlist_bl_head *h) |
| 22 | { |
| 23 | return (struct hlist_bl_node *) |
| 24 | ((unsigned long)rcu_dereference_check(h->first, hlist_bl_is_locked(h)) & ~LIST_BL_LOCKMASK); |
| 25 | } |
| 26 | |
| 27 | /** |
| 28 | * hlist_bl_del_rcu - deletes entry from hash list without re-initialization |
| 29 | * @n: the element to delete from the hash list. |
| 30 | * |
| 31 | * Note: hlist_bl_unhashed() on entry does not return true after this, |
| 32 | * the entry is in an undefined state. It is useful for RCU based |
| 33 | * lockfree traversal. |
| 34 | * |
| 35 | * In particular, it means that we can not poison the forward |
| 36 | * pointers that may still be used for walking the hash list. |
| 37 | * |
| 38 | * The caller must take whatever precautions are necessary |
| 39 | * (such as holding appropriate locks) to avoid racing |
| 40 | * with another list-mutation primitive, such as hlist_bl_add_head_rcu() |
| 41 | * or hlist_bl_del_rcu(), running on this same list. |
| 42 | * However, it is perfectly legal to run concurrently with |
| 43 | * the _rcu list-traversal primitives, such as |
| 44 | * hlist_bl_for_each_entry(). |
| 45 | */ |
| 46 | static inline void hlist_bl_del_rcu(struct hlist_bl_node *n) |
| 47 | { |
| 48 | __hlist_bl_del(n); |
| 49 | n->pprev = LIST_POISON2; |
| 50 | } |
| 51 | |
| 52 | /** |
| 53 | * hlist_bl_add_head_rcu |
| 54 | * @n: the element to add to the hash list. |
| 55 | * @h: the list to add to. |
| 56 | * |
| 57 | * Description: |
| 58 | * Adds the specified element to the specified hlist_bl, |
| 59 | * while permitting racing traversals. |
| 60 | * |
| 61 | * The caller must take whatever precautions are necessary |
| 62 | * (such as holding appropriate locks) to avoid racing |
| 63 | * with another list-mutation primitive, such as hlist_bl_add_head_rcu() |
| 64 | * or hlist_bl_del_rcu(), running on this same list. |
| 65 | * However, it is perfectly legal to run concurrently with |
| 66 | * the _rcu list-traversal primitives, such as |
| 67 | * hlist_bl_for_each_entry_rcu(), used to prevent memory-consistency |
| 68 | * problems on Alpha CPUs. Regardless of the type of CPU, the |
| 69 | * list-traversal primitive must be guarded by rcu_read_lock(). |
| 70 | */ |
| 71 | static inline void hlist_bl_add_head_rcu(struct hlist_bl_node *n, |
| 72 | struct hlist_bl_head *h) |
| 73 | { |
| 74 | struct hlist_bl_node *first; |
| 75 | |
| 76 | /* don't need hlist_bl_first_rcu because we're under lock */ |
| 77 | first = hlist_bl_first(h); |
| 78 | |
| 79 | n->next = first; |
| 80 | if (first) |
| 81 | first->pprev = &n->next; |
| 82 | n->pprev = &h->first; |
| 83 | |
| 84 | /* need _rcu because we can have concurrent lock free readers */ |
| 85 | hlist_bl_set_first_rcu(h, n); |
| 86 | } |
| 87 | /** |
| 88 | * hlist_bl_for_each_entry_rcu - iterate over rcu list of given type |
| 89 | * @tpos: the type * to use as a loop cursor. |
| 90 | * @pos: the &struct hlist_bl_node to use as a loop cursor. |
| 91 | * @head: the head for your list. |
| 92 | * @member: the name of the hlist_bl_node within the struct. |
| 93 | * |
| 94 | */ |
| 95 | #define hlist_bl_for_each_entry_rcu(tpos, pos, head, member) \ |
| 96 | for (pos = hlist_bl_first_rcu(head); \ |
| 97 | pos && \ |
| 98 | ({ tpos = hlist_bl_entry(pos, typeof(*tpos), member); 1; }); \ |
| 99 | pos = rcu_dereference_raw(pos->next)) |
| 100 | |
| 101 | #endif |