From patchwork Mon Nov 29 13:32:47 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Luca Coelho X-Patchwork-Id: 517864 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9CD56C43219 for ; Mon, 29 Nov 2021 13:35:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1377668AbhK2Nig (ORCPT ); Mon, 29 Nov 2021 08:38:36 -0500 Received: from paleale.coelho.fi ([176.9.41.70]:49850 "EHLO farmhouse.coelho.fi" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1377765AbhK2Ng3 (ORCPT ); Mon, 29 Nov 2021 08:36:29 -0500 Received: from 91-156-6-193.elisa-laajakaista.fi ([91.156.6.193] helo=kveik.ger.corp.intel.com) by farmhouse.coelho.fi with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1mrgmI-0012xo-8W; Mon, 29 Nov 2021 15:33:06 +0200 From: Luca Coelho To: johannes@sipsolutions.net Cc: luca@coelho.fi, linux-wireless@vger.kernel.org Date: Mon, 29 Nov 2021 15:32:47 +0200 Message-Id: X-Mailer: git-send-email 2.33.1 In-Reply-To: <20211129133248.83829-1-luca@coelho.fi> References: <20211129133248.83829-1-luca@coelho.fi> MIME-Version: 1.0 Subject: [PATCH 15/16] mac80211: agg-tx: don't schedule_and_wake_txq() under sta->lock Precedence: bulk List-ID: X-Mailing-List: linux-wireless@vger.kernel.org From: Johannes Berg When we call ieee80211_agg_start_txq(), that will in turn call schedule_and_wake_txq(). Called from ieee80211_stop_tx_ba_cb() this is done under sta->lock, which leads to certain circular lock dependencies, as reported by Chris Murphy: https://lore.kernel.org/r/CAJCQCtSXJ5qA4bqSPY=oLRMbv-irihVvP7A2uGutEbXQVkoNaw@mail.gmail.com In general, ieee80211_agg_start_txq() is usually not called with sta->lock held, only in this one place. But it's always called with sta->ampdu_mlme.mtx held, and that's therefore clearly sufficient. Change ieee80211_stop_tx_ba_cb() to also call it without the sta->lock held, by factoring it out of ieee80211_remove_tid_tx() (which is only called in this one place). This breaks the locking chain and makes it less likely that we'll have similar locking chain problems in the future. Reported-by: Chris Murphy Signed-off-by: Johannes Berg Signed-off-by: Luca Coelho --- net/mac80211/agg-tx.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/net/mac80211/agg-tx.c b/net/mac80211/agg-tx.c index 430a58587538..4dd56daed89b 100644 --- a/net/mac80211/agg-tx.c +++ b/net/mac80211/agg-tx.c @@ -9,7 +9,7 @@ * Copyright 2007, Michael Wu * Copyright 2007-2010, Intel Corporation * Copyright(c) 2015-2017 Intel Deutschland GmbH - * Copyright (C) 2018 - 2020 Intel Corporation + * Copyright (C) 2018 - 2021 Intel Corporation */ #include @@ -213,6 +213,8 @@ ieee80211_agg_start_txq(struct sta_info *sta, int tid, bool enable) struct ieee80211_txq *txq = sta->sta.txq[tid]; struct txq_info *txqi; + lockdep_assert_held(&sta->ampdu_mlme.mtx); + if (!txq) return; @@ -290,7 +292,6 @@ static void ieee80211_remove_tid_tx(struct sta_info *sta, int tid) ieee80211_assign_tid_tx(sta, tid, NULL); ieee80211_agg_splice_finish(sta->sdata, tid); - ieee80211_agg_start_txq(sta, tid, false); kfree_rcu(tid_tx, rcu_head); } @@ -889,6 +890,7 @@ void ieee80211_stop_tx_ba_cb(struct sta_info *sta, int tid, { struct ieee80211_sub_if_data *sdata = sta->sdata; bool send_delba = false; + bool start_txq = false; ht_dbg(sdata, "Stopping Tx BA session for %pM tid %d\n", sta->sta.addr, tid); @@ -906,10 +908,14 @@ void ieee80211_stop_tx_ba_cb(struct sta_info *sta, int tid, send_delba = true; ieee80211_remove_tid_tx(sta, tid); + start_txq = true; unlock_sta: spin_unlock_bh(&sta->lock); + if (start_txq) + ieee80211_agg_start_txq(sta, tid, false); + if (send_delba) ieee80211_send_delba(sdata, sta->sta.addr, tid, WLAN_BACK_INITIATOR, WLAN_REASON_QSTA_NOT_USE);