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From:   Alexander Wetzel <alexander@wetzel-home.de>
To:     ath10k@lists.infradead.org
Cc:     linux-wireless@vger.kernel.org,
        =?UTF-8?q?Toke=20H=C3=B8iland-J=C3=B8rgensen?= <toke@toke.dk>,
        Alexander Wetzel <alexander@wetzel-home.de>,
        Felix Fietkau <nbd@nbd.name>, stable@vger.kernel.org
Subject: [PATCH] wifi: ath10k: Serialize wake_tx_queue ops
Date:   Thu, 23 Mar 2023 17:55:27 +0100
Message-Id: <20230323165527.156414-1-alexander@wetzel-home.de>
MIME-Version: 1.0
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Precedence: bulk

Serialize the ath10k implementation of the wake_tx_queue ops.
ath10k_mac_op_wake_tx_queue() must not run concurrent since it's using
ieee80211_txq_schedule_start().

Fixes: bb2edb733586 ("ath10k: migrate to mac80211 txq scheduling")
Reported-by: Felix Fietkau <nbd@nbd.name>
Link: https://lore.kernel.org/r/519b5bb9-8899-ae7c-4eff-f3116cdfdb56@nbd.name
CC: <stable@vger.kernel.org>
Signed-off-by: Alexander Wetzel <alexander@wetzel-home.de>
---

The intend of this patch is to sort out an issue discovered in the discussion
referred to by the Link tag.

I can't test it with real HW and thus just implemented the per-ac queue lock
Felix suggested. One obvious alternative to the per-ac lock would be to
bring back the txqs_lock commit bb2edb733586 ("ath10k: migrate to mac80211 txq
scheduling") dropped.

Alexander

---
 drivers/net/wireless/ath/ath10k/core.c | 3 +++
 drivers/net/wireless/ath/ath10k/core.h | 3 +++
 drivers/net/wireless/ath/ath10k/mac.c  | 6 ++++--
 3 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/net/wireless/ath/ath10k/core.c b/drivers/net/wireless/ath/ath10k/core.c
index 5eb131ab916f..533ed7169e11 100644
--- a/drivers/net/wireless/ath/ath10k/core.c
+++ b/drivers/net/wireless/ath/ath10k/core.c
@@ -3643,6 +3643,9 @@ struct ath10k *ath10k_core_create(size_t priv_size, struct device *dev,
 	mutex_init(&ar->dump_mutex);
 	spin_lock_init(&ar->data_lock);
 
+	for (int ac = 0; ac < IEEE80211_NUM_ACS; ac++)
+		spin_lock_init(&ar->queue_lock[ac]);
+
 	INIT_LIST_HEAD(&ar->peers);
 	init_waitqueue_head(&ar->peer_mapping_wq);
 	init_waitqueue_head(&ar->htt.empty_tx_wq);
diff --git a/drivers/net/wireless/ath/ath10k/core.h b/drivers/net/wireless/ath/ath10k/core.h
index f5de8ce8fb45..4b5239de4018 100644
--- a/drivers/net/wireless/ath/ath10k/core.h
+++ b/drivers/net/wireless/ath/ath10k/core.h
@@ -1170,6 +1170,9 @@ struct ath10k {
 	/* protects shared structure data */
 	spinlock_t data_lock;
 
+	/* serialize wake_tx_queue calls per ac */
+	spinlock_t queue_lock[IEEE80211_NUM_ACS];
+
 	struct list_head arvifs;
 	struct list_head peers;
 	struct ath10k_peer *peer_map[ATH10K_MAX_NUM_PEER_IDS];
diff --git a/drivers/net/wireless/ath/ath10k/mac.c b/drivers/net/wireless/ath/ath10k/mac.c
index 7675858f069b..9c4bf2fdbc0f 100644
--- a/drivers/net/wireless/ath/ath10k/mac.c
+++ b/drivers/net/wireless/ath/ath10k/mac.c
@@ -4732,13 +4732,14 @@ static void ath10k_mac_op_wake_tx_queue(struct ieee80211_hw *hw,
 {
 	struct ath10k *ar = hw->priv;
 	int ret;
-	u8 ac;
+	u8 ac = txq->ac;
 
 	ath10k_htt_tx_txq_update(hw, txq);
 	if (ar->htt.tx_q_state.mode != HTT_TX_MODE_SWITCH_PUSH)
 		return;
 
-	ac = txq->ac;
+	spin_lock_bh(&ar->queue_lock[ac]);
+
 	ieee80211_txq_schedule_start(hw, ac);
 	txq = ieee80211_next_txq(hw, ac);
 	if (!txq)
@@ -4753,6 +4754,7 @@ static void ath10k_mac_op_wake_tx_queue(struct ieee80211_hw *hw,
 	ath10k_htt_tx_txq_update(hw, txq);
 out:
 	ieee80211_txq_schedule_end(hw, ac);
+	spin_unlock_bh(&ar->queue_lock[ac]);
 }
 
 /* Must not be called with conf_mutex held as workers can use that also. */
-- 
2.40.0