Return-path: Received: from mail.neratec.com ([46.140.151.2]:20484 "EHLO mail.neratec.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751487AbbFAOvq (ORCPT ); Mon, 1 Jun 2015 10:51:46 -0400 From: Wojciech Dubowik To: linux-wireless@vger.kernel.org Cc: julian.calaby@gmail.com, Wojciech Dubowik Subject: [PATCH v2] mac80211: Fix double locking on CSA counter update Date: Mon, 1 Jun 2015 16:51:31 +0200 Message-Id: <1433170291-28665-1-git-send-email-Wojciech.Dubowik@neratec.com> (sfid-20150601_165150_599042_C9CB69CD) Sender: linux-wireless-owner@vger.kernel.org List-ID: We call rcu locked ieee80211_csa_update_counter from already locked section. Fix it by splitting ieee80211_csa_update_counter into locked and unlocked variants and use the latter in rcu locked section. v2: Use splitted functions instead of direct counter decrement. Signed-off-by: Wojciech Dubowik --- net/mac80211/tx.c | 22 ++++++++++++++-------- 1 file changed, 14 insertions(+), 8 deletions(-) diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c index 8df1342..312b199 100644 --- a/net/mac80211/tx.c +++ b/net/mac80211/tx.c @@ -3216,6 +3216,16 @@ static void ieee80211_set_csa(struct ieee80211_sub_if_data *sdata, rcu_read_unlock(); } +static u8 __ieee80211_csa_update_counter(struct beacon_data *beacon) +{ + beacon->csa_current_counter--; + + /* the counter should never reach 0 */ + WARN_ON_ONCE(!beacon->csa_current_counter); + + return beacon->csa_current_counter; +} + u8 ieee80211_csa_update_counter(struct ieee80211_vif *vif) { struct ieee80211_sub_if_data *sdata = vif_to_sdata(vif); @@ -3234,11 +3244,7 @@ u8 ieee80211_csa_update_counter(struct ieee80211_vif *vif) if (!beacon) goto unlock; - beacon->csa_current_counter--; - - /* the counter should never reach 0 */ - WARN_ON_ONCE(!beacon->csa_current_counter); - count = beacon->csa_current_counter; + count = __ieee80211_csa_update_counter(beacon); unlock: rcu_read_unlock(); @@ -3338,7 +3344,7 @@ __ieee80211_beacon_get(struct ieee80211_hw *hw, if (beacon) { if (beacon->csa_counter_offsets[0]) { if (!is_template) - ieee80211_csa_update_counter(vif); + __ieee80211_csa_update_counter(beacon); ieee80211_set_csa(sdata, beacon); } @@ -3384,7 +3390,7 @@ __ieee80211_beacon_get(struct ieee80211_hw *hw, if (beacon->csa_counter_offsets[0]) { if (!is_template) - ieee80211_csa_update_counter(vif); + __ieee80211_csa_update_counter(beacon); ieee80211_set_csa(sdata, beacon); } @@ -3414,7 +3420,7 @@ __ieee80211_beacon_get(struct ieee80211_hw *hw, * for now we leave it consistent with overall * mac80211's behavior. */ - ieee80211_csa_update_counter(vif); + __ieee80211_csa_update_counter(beacon); ieee80211_set_csa(sdata, beacon); } -- 1.9.1