Return-path: Received: from mail-wi0-f172.google.com ([209.85.212.172]:49789 "EHLO mail-wi0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933541AbaE2GqS (ORCPT ); Thu, 29 May 2014 02:46:18 -0400 Received: by mail-wi0-f172.google.com with SMTP id hi2so4930789wib.11 for ; Wed, 28 May 2014 23:46:17 -0700 (PDT) From: Michal Kazior To: linux-wireless@vger.kernel.org Cc: johannes@sipsolutions.net, Michal Kazior Subject: [PATCH v2 2/2] mac80211: use csa counter offsets instead of csa_active Date: Thu, 29 May 2014 08:38:55 +0200 Message-Id: <1401345535-22991-3-git-send-email-michal.kazior@tieto.com> (sfid-20140529_084643_761016_E73A6979) In-Reply-To: <1401345535-22991-1-git-send-email-michal.kazior@tieto.com> References: <1401345535-22991-1-git-send-email-michal.kazior@tieto.com> Sender: linux-wireless-owner@vger.kernel.org List-ID: vif->csa_active is protected by mutexes only. This means it is unreliable to depend on it on codeflow in non-sleepable beacon and CSA code. There was no guarantee to have vif->csa_active update be visible before beacons are updated on SMP systems. Using csa counter offsets which are embedded in beacon struct (and thus are protected with single RCU assignment) is much safer. Signed-off-by: Michal Kazior --- net/mac80211/tx.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c index acad42a..0211590 100644 --- a/net/mac80211/tx.c +++ b/net/mac80211/tx.c @@ -2536,6 +2536,9 @@ bool ieee80211_csa_is_complete(struct ieee80211_vif *vif) goto out; } + if (!beacon->csa_counter_offsets[0]) + goto out; + if (WARN_ON_ONCE(beacon->csa_counter_offsets[0] > beacon_data_len)) goto out; @@ -2580,7 +2583,7 @@ __ieee80211_beacon_get(struct ieee80211_hw *hw, beacon = rcu_dereference(ap->beacon); if (beacon) { - if (sdata->vif.csa_active) { + if (beacon->csa_counter_offsets[0]) { if (!is_template) ieee80211_csa_update_counter(vif); @@ -2626,7 +2629,7 @@ __ieee80211_beacon_get(struct ieee80211_hw *hw, if (!beacon) goto out; - if (sdata->vif.csa_active) { + if (beacon->csa_counter_offsets[0]) { if (!is_template) ieee80211_csa_update_counter(vif); @@ -2651,7 +2654,7 @@ __ieee80211_beacon_get(struct ieee80211_hw *hw, if (!beacon) goto out; - if (sdata->vif.csa_active) { + if (beacon->csa_counter_offsets[0]) { if (!is_template) /* TODO: For mesh csa_counter is in TU, so * decrementing it by one isn't correct, but -- 1.8.5.3