4.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: David S. Miller davem@davemloft.net
commit 1602f49b58abcb0d34a5f0a29d68e7c1769547aa upstream.
[This commit was a merge, but it added hlist_add_tail_rcu(), which is what we need in this stable tree, so I've changed the subject to be more descriptive - gregkh]
Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- include/linux/rculist.h | 36 ++++++++++++++++++++++++++++++++++++ 1 file changed, 36 insertions(+)
--- a/include/linux/rculist.h +++ b/include/linux/rculist.h @@ -402,6 +402,42 @@ static inline void hlist_add_head_rcu(st }
/** + * 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; + + for (i = hlist_first_rcu(h); i; i = hlist_next_rcu(i)) + last = i; + + if (last) { + n->next = last->next; + 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.