diff options
| -rw-r--r-- | include/linux/rculist.h | 28 |
1 files changed, 28 insertions, 0 deletions
diff --git a/include/linux/rculist.h b/include/linux/rculist.h index b0f39be08b6c..eb4443c7e05b 100644 --- a/include/linux/rculist.h +++ b/include/linux/rculist.h @@ -98,6 +98,34 @@ static inline void list_del_rcu(struct list_head *entry) } /** + * 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); + n->pprev = NULL; + } +} + +/** * list_replace_rcu - replace old entry by new one * @old : the element to be replaced * @new : the new element to insert |