From patchwork Fri Nov 8 14:39:36 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Luca Coelho X-Patchwork-Id: 3158211 Return-Path: X-Original-To: patchwork-linux-wireless@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork2.web.kernel.org (Postfix) with ESMTP id 64BE9C0E9B for ; Fri, 8 Nov 2013 14:46:23 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 8944D2073D for ; Fri, 8 Nov 2013 14:40:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 309682073A for ; Fri, 8 Nov 2013 14:40:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757092Ab3KHOkX (ORCPT ); Fri, 8 Nov 2013 09:40:23 -0500 Received: from emh02.mail.saunalahti.fi ([62.142.5.108]:47641 "EHLO emh02.mail.saunalahti.fi" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753977Ab3KHOkW (ORCPT ); Fri, 8 Nov 2013 09:40:22 -0500 Received: from porter.coelho.fi (a88-113-229-85.elisa-laajakaista.fi [88.113.229.85]) by emh02.mail.saunalahti.fi (Postfix) with ESMTP id E6F388192D; Fri, 8 Nov 2013 16:40:19 +0200 (EET) From: Luciano Coelho To: linux-wireless@vger.kernel.org, sw@simonwunderlich.de, johannes@sipsolutions.net Subject: [RFC v3 1/4] mac80211: don't transmit beacon with CSA count 0 Date: Fri, 8 Nov 2013 16:39:36 +0200 Message-Id: <1383921579-22373-1-git-send-email-luciano.coelho@intel.com> X-Mailer: git-send-email 1.8.4.rc3 Sender: linux-wireless-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-wireless@vger.kernel.org X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP A beacon should never have a Channel Switch Announcement information element with a count of 0, because a count of 1 means switch just before the next beacon. So, if a count of 0 was valid in a beacon, it would have been transmitted in the next channel already, which is useless. A CSA count equal to zero is only meaningful in action frames or probe_responses. Fix the ieee80211_csa_is_complete() and ieee80211_update_csa() functions accordingly. Signed-off-by: Luciano Coelho --- In v2, updated the documentation to reflect the change. This is going to be sent to linux-wireless for comments from the community too. In v3, removed the part of the documentation that belongs in the next patch. include/net/mac80211.h | 8 ++++---- net/mac80211/tx.c | 10 +++++++--- 2 files changed, 11 insertions(+), 7 deletions(-) diff --git a/include/net/mac80211.h b/include/net/mac80211.h index 7ceed99..ec6ed6d 100644 --- a/include/net/mac80211.h +++ b/include/net/mac80211.h @@ -2680,10 +2680,10 @@ enum ieee80211_roc_type { * @channel_switch_beacon: Starts a channel switch to a new channel. * Beacons are modified to include CSA or ECSA IEs before calling this * function. The corresponding count fields in these IEs must be - * decremented, and when they reach zero the driver must call + * decremented, and when they reach 1 the driver must call * ieee80211_csa_finish(). Drivers which use ieee80211_beacon_get() * get the csa counter decremented by mac80211, but must check if it is - * zero using ieee80211_csa_is_complete() after the beacon has been + * 1 using ieee80211_csa_is_complete() after the beacon has been * transmitted and then call ieee80211_csa_finish(). * * @join_ibss: Join an IBSS (on an IBSS interface); this is called after all @@ -3383,13 +3383,13 @@ static inline struct sk_buff *ieee80211_beacon_get(struct ieee80211_hw *hw, * @vif: &struct ieee80211_vif pointer from the add_interface callback. * * After a channel switch announcement was scheduled and the counter in this - * announcement hit zero, this function must be called by the driver to + * announcement hits 1, this function must be called by the driver to * notify mac80211 that the channel can be changed. */ void ieee80211_csa_finish(struct ieee80211_vif *vif); /** - * ieee80211_csa_is_complete - find out if counters reached zero + * ieee80211_csa_is_complete - find out if counters reached 1 * @vif: &struct ieee80211_vif pointer from the add_interface callback. * * This function returns whether the channel switch counters reached zero. diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c index c558b24..57d9feb 100644 --- a/net/mac80211/tx.c +++ b/net/mac80211/tx.c @@ -2409,8 +2409,12 @@ static void ieee80211_update_csa(struct ieee80211_sub_if_data *sdata, if (WARN_ON(counter_offset_beacon >= beacon_data_len)) return; - /* warn if the driver did not check for/react to csa completeness */ - if (WARN_ON(beacon_data[counter_offset_beacon] == 0)) + /* Warn if the driver did not check for/react to csa + * completeness. A beacon with CSA counter set to 0 should + * never occur, because a counter of 1 means switch just + * before the next beacon. + */ + if (WARN_ON(beacon_data[counter_offset_beacon] == 1)) return; beacon_data[counter_offset_beacon]--; @@ -2476,7 +2480,7 @@ bool ieee80211_csa_is_complete(struct ieee80211_vif *vif) if (WARN_ON(counter_beacon > beacon_data_len)) goto out; - if (beacon_data[counter_beacon] == 0) + if (beacon_data[counter_beacon] == 1) ret = true; out: rcu_read_unlock();