From cee271678d0e3177a25d0fcb2fa5e051d48e4262 Mon Sep 17 00:00:00 2001 From: Björn Töpel Date: Mon, 8 Oct 2018 19:40:16 +0200 Subject: xsk: do not call synchronize_net() under RCU read lock MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The XSKMAP update and delete functions called synchronize_net(), which can sleep. It is not allowed to sleep during an RCU read section. Instead we need to make sure that the sock sk_destruct (xsk_destruct) function is asynchronously called after an RCU grace period. Setting the SOCK_RCU_FREE flag for XDP sockets takes care of this. Fixes: fbfc504a24f5 ("bpf: introduce new bpf AF_XDP map type BPF_MAP_TYPE_XSKMAP") Reported-by: Eric Dumazet Signed-off-by: Björn Töpel Acked-by: Song Liu Signed-off-by: Daniel Borkmann --- kernel/bpf/xskmap.c | 10 ++-------- 1 file changed, 2 insertions(+), 8 deletions(-) (limited to 'kernel') diff --git a/kernel/bpf/xskmap.c b/kernel/bpf/xskmap.c index 9f8463afda9c..47147c9e184d 100644 --- a/kernel/bpf/xskmap.c +++ b/kernel/bpf/xskmap.c @@ -192,11 +192,8 @@ static int xsk_map_update_elem(struct bpf_map *map, void *key, void *value, sock_hold(sock->sk); old_xs = xchg(&m->xsk_map[i], xs); - if (old_xs) { - /* Make sure we've flushed everything. */ - synchronize_net(); + if (old_xs) sock_put((struct sock *)old_xs); - } sockfd_put(sock); return 0; @@ -212,11 +209,8 @@ static int xsk_map_delete_elem(struct bpf_map *map, void *key) return -EINVAL; old_xs = xchg(&m->xsk_map[k], NULL); - if (old_xs) { - /* Make sure we've flushed everything. */ - synchronize_net(); + if (old_xs) sock_put((struct sock *)old_xs); - } return 0; } -- cgit v1.2.3-59-g8ed1b