From patchwork Fri Feb 26 13:19:50 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Andreas Pape X-Patchwork-Id: 15852 X-Patchwork-Delegate: mareklindner@neomailbox.ch Return-Path: X-Original-To: patchwork@open-mesh.org Delivered-To: patchwork@open-mesh.org Received: from open-mesh.org (localhost [127.0.0.1]) by open-mesh.org (Postfix) with ESMTP id D705481718; Fri, 26 Feb 2016 14:19:55 +0100 (CET) Received-SPF: None (no SPF record) identity=mailfrom; client-ip=62.157.123.121; helo=mail2.phoenixcontact.com; envelope-from=apape@phoenixcontact.com; receiver=b.a.t.m.a.n@lists.open-mesh.org Authentication-Results: open-mesh.org; dmarc=none header.from=phoenixcontact.com Received: from mail2.phoenixcontact.com (mail2.phoenixcontact.com [62.157.123.121]) by open-mesh.org (Postfix) with ESMTPS id 3A61C81696 for ; Fri, 26 Feb 2016 14:19:55 +0100 (CET) Received: from localhost.localdomain ([149.208.237.66]) by de-nice01.de.phoenixcontact.com with ESMTP id 2016022614195327-38991 ; Fri, 26 Feb 2016 14:19:53 +0100 From: Andreas Pape To: b.a.t.m.a.n@lists.open-mesh.org X-Mailer: git-send-email 1.7.0.4 X-MIMETrack: Itemize by SMTP Server on DE-NICE01/Hub/SRV/DE/Phoenix Contact at 26.02.2016 14:19:53, Serialize by ntm_grab.EXE on nemex02/spoke/SRV/DE/Phoenix Contact at 26.02.2016 14:19:46, Serialize complete at 26.02.2016 14:19:46, Itemize by ntm_grab.EXE on nemex02/spoke/SRV/DE/Phoenix Contact at 26.02.2016 14:19:46, Serialize by Router on nemex02/spoke/SRV/DE/Phoenix Contact at 26.02.2016 14:19:47, Serialize complete at 26.02.2016 14:19:47 X-TNEFEvaluated: 1 Message-ID: <1456492790-29897-1-git-send-email-apape@phoenixcontact.com> Date: Fri, 26 Feb 2016 14:19:50 +0100 content-transfer-encoding: quoted-printable content-type: text/plain; charset="utf-8" Subject: [B.A.T.M.A.N.] [PATCHv2 7/7] batman-adv: handle race condition for claims between gateways X-BeenThere: b.a.t.m.a.n@lists.open-mesh.org X-Mailman-Version: 2.1.18 Precedence: list List-Id: The list for a Better Approach To Mobile Ad-hoc Networking List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: The list for a Better Approach To Mobile Ad-hoc Networking Errors-To: b.a.t.m.a.n-bounces@lists.open-mesh.org Sender: "B.A.T.M.A.N" Consider the following situation which has been found in a test setup: Gateway B has claimed client C and gateway A has the same backbone network as B. C sends a broad- or multicast to B and directly after this packet decides to send another packet to A due to a better TQ value. B will forward the broad-/multicast into the backbone as it is the responsible gw and after that A will claim C as it has been chosen by C as the new gateway. If it now happens that A claims C before it has received the broad-/multicast forwarded by B (due to backbone topology or due to some delay in B when forwarding the packet) we get a critical situation: in the current code A will immediately unclaim C when receiving the multicast due to the roaming client scenario although the position of C has not changed in the mesh. If this happens the multi-/broadcast forwarded by B will be sent back into the mesh by A and we have looping packets until one of the gateways claims C again. In order to prevent this, unclaiming of a client due to the roaming client scenario is only done after a certain time is expired after the last claim of the client. 100 ms are used here, which should be slow enough for big backbones and slow gateways but fast enough not to break the roaming client use case. Signed-off-by: Andreas Pape Acked-by: Simon Wunderlich --- net/batman-adv/bridge_loop_avoidance.c | 20 ++++++++++++++++---- 1 files changed, 16 insertions(+), 4 deletions(-) -- 1.7.0.4 .................................................................. PHOENIX CONTACT ELECTRONICS GmbH Sitz der Gesellschaft / registered office of the company: 31812 Bad Pyrmont USt-Id-Nr.: DE811742156 Amtsgericht Hannover HRB 100528 / district court Hannover HRB 100528 Geschäftsführer / Executive Board: Roland Bent, Dr. Martin Heubeck diff --git a/net/batman-adv/bridge_loop_avoidance.c b/net/batman-adv/bridge_loop_avoidance.c index 32a6168..98f0dd9 100644 --- a/net/batman-adv/bridge_loop_avoidance.c +++ b/net/batman-adv/bridge_loop_avoidance.c @@ -1764,10 +1764,22 @@ int batadv_bla_tx(struct batadv_priv *bat_priv, struct sk_buff *skb, /* if yes, the client has roamed and we have * to unclaim it. */ - batadv_handle_unclaim(bat_priv, primary_if, - primary_if->net_dev->dev_addr, - ethhdr->h_source, vid); - goto allow; + if (batadv_has_timed_out(claim->lasttime, 100)) { + /* only unclaim if the last claim entry is + * older than 100 ms to make sure we really + * have a roaming client here. + */ + batadv_dbg(BATADV_DBG_BLA, bat_priv, "bla_tx(): Roaming client %pM detected. Unclaim it.\n", + ethhdr->h_source); + batadv_handle_unclaim(bat_priv, primary_if, + primary_if->net_dev->dev_addr, + ethhdr->h_source, vid); + goto allow; + } else { + batadv_dbg(BATADV_DBG_BLA, bat_priv, "bla_tx(): Race for claim %pM detected. Drop packet.\n", + ethhdr->h_source); + goto handled; + } } /* check if it is a multicast/broadcast frame */