I needed to add into the middle of an RCU list, does this make sense.
>From a45892b0d49ac5fe449ba7e19c646cb17f7cee57 Mon Sep 17 00:00:00 2001 From: Stephen Hemminger <step...@networkplumber.org> Date: Thu, 22 Aug 2013 21:27:04 -0700 Subject: [PATCH] Add list_splice_init_rcu to allow insertion into a RCU list Simplified version of the version in kernel. --- urcu/rculist.h | 32 ++++++++++++++++++++++++++++++++ 1 file changed, 32 insertions(+) diff --git a/urcu/rculist.h b/urcu/rculist.h index 1fd2df3..2e8a5a0 100644 --- a/urcu/rculist.h +++ b/urcu/rculist.h @@ -72,6 +72,38 @@ void cds_list_del_rcu(struct cds_list_head *elem) CMM_STORE_SHARED(elem->prev->next, elem->next); } + +/** + * Splice an RCU-protected list into an existing list. + * + * Note that this function blocks in synchronize_rcu() + * + * Important note: this function is not called concurrently + * with other updates to the list. + */ +static inline void caa_list_splice_init_rcu(struct cds_list_head *list, + struct cds_list_head *head) +{ + struct cds_list_head *first = list->next; + struct cds_list_head *last = list->prev; + struct cds_list_head *at = head->next; + + if (cds_list_empty(list)) + return; + + /* "first" and "last" tracking list, so initialize it. */ + CDS_INIT_LIST_HEAD(list); + + /* Wait for any readers to finish using the list before splicing */ + synchronize_rcu(); + + /* Readers are finished with the source list, so perform splice. */ + last->next = at; + rcu_assign_pointer(head->next, first); + first->prev = head; + at->prev = last; +} + /* * Iteration through all elements of the list must be done while rcu_read_lock() * is held. -- 1.7.10.4 _______________________________________________ lttng-dev mailing list lttng-dev@lists.lttng.org http://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev