From 3eec4eb899dd154cadccbaf0822058c040df4638 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Toke=20H=C3=B8iland-J=C3=B8rgensen?= Date: Fri, 28 Jun 2019 11:12:34 +0200 Subject: [PATCH] UPSTREAM: xskmap: Move non-standard list manipulation to helper MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Add a helper in list.h for the non-standard way of clearing a list that is used in xskmap. This makes it easier to reuse it in the other map types, and also makes sure this usage is not forgotten in any list refactorings in the future. Change-Id: I3717523d2a890fad4e026aedb5066e1cc75d4d5b Signed-off-by: Toke Høiland-Jørgensen Signed-off-by: Daniel Borkmann Signed-off-by: Sorayukii --- include/linux/list.h | 14 ++++++++++++++ kernel/bpf/xskmap.c | 3 +-- 2 files changed, 15 insertions(+), 2 deletions(-) diff --git a/include/linux/list.h b/include/linux/list.h index 85baa403499d..ee7b17096212 100644 --- a/include/linux/list.h +++ b/include/linux/list.h @@ -105,6 +105,20 @@ static inline void __list_del(struct list_head * prev, struct list_head * next) WRITE_ONCE(prev->next, next); } +/* + * Delete a list entry and clear the 'prev' pointer. + * + * This is a special-purpose list clearing method used in the networking code + * for lists allocated as per-cpu, where we don't want to incur the extra + * WRITE_ONCE() overhead of a regular list_del_init(). The code that uses this + * needs to check the node 'prev' pointer instead of calling list_empty(). + */ +static inline void __list_del_clearprev(struct list_head *entry) +{ + __list_del(entry->prev, entry->next); + entry->prev = NULL; +} + /** * list_del - deletes entry from list. * @entry: the element to delete from the list. diff --git a/kernel/bpf/xskmap.c b/kernel/bpf/xskmap.c index ef7338cebd18..9bb96ace9fa1 100644 --- a/kernel/bpf/xskmap.c +++ b/kernel/bpf/xskmap.c @@ -145,8 +145,7 @@ void __xsk_map_flush(struct bpf_map *map) list_for_each_entry_safe(xs, tmp, flush_list, flush_node) { xsk_flush(xs); - __list_del(xs->flush_node.prev, xs->flush_node.next); - xs->flush_node.prev = NULL; + __list_del_clearprev(&xs->flush_node); } }