From: Johannes Berg johannes.berg@intel.com
[ Upstream commit 06c41bda0ea14aa7fba932a9613c4ee239682cf0 ]
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-irihVvP7A2uGutEbXQVkoNa...
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.
Fixes: ba8c3d6f16a1 ("mac80211: add an intermediate software queue implementation") Reported-by: Chris Murphy lists@colorremedies.com Signed-off-by: Johannes Berg johannes.berg@intel.com Signed-off-by: Luca Coelho luciano.coelho@intel.com Link: https://lore.kernel.org/r/iwlwifi.20211202152554.f519884c8784.I555fef8e67d93... Signed-off-by: Johannes Berg johannes.berg@intel.com Signed-off-by: Sasha Levin sashal@kernel.org --- 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 58761ca7da3c5..74a878f213d3e 100644 --- a/net/mac80211/agg-tx.c +++ b/net/mac80211/agg-tx.c @@ -9,7 +9,7 @@ * Copyright 2007, Michael Wu flamingice@sourmilk.net * 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 <linux/ieee80211.h> @@ -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);