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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Sean Wang <sean.wang@mediatek.com>,
        Felix Fietkau <nbd@nbd.name>, Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.11 474/601] mt76: mt7663s: fix the possible device hang in high traffic
Date:   Wed, 12 May 2021 16:49:11 +0200
Message-Id: <20210512144843.458619238@linuxfoundation.org>
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From: Sean Wang <sean.wang@mediatek.com>

[ Upstream commit 45247a85614b49b07b9dc59a4e6783b17e766ff2 ]

Use the additional memory barrier to ensure the skb list up-to-date
between the skb producer and consumer to avoid the invalid skb content
written into sdio controller and then cause device hang due to mcu assert
caught by WR_TIMEOUT_INT.

Fixes: 1522ff731f84 ("mt76: mt7663s: introduce sdio tx aggregation")
Signed-off-by: Sean Wang <sean.wang@mediatek.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/net/wireless/mediatek/mt76/mt7615/sdio_txrx.c | 2 ++
 drivers/net/wireless/mediatek/mt76/sdio.c             | 3 +++
 2 files changed, 5 insertions(+)

diff --git a/drivers/net/wireless/mediatek/mt76/mt7615/sdio_txrx.c b/drivers/net/wireless/mediatek/mt76/mt7615/sdio_txrx.c
index 37fe65ced4fd..4393dd21ebbb 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7615/sdio_txrx.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7615/sdio_txrx.c
@@ -225,6 +225,8 @@ static int mt7663s_tx_run_queue(struct mt76_dev *dev, struct mt76_queue *q)
 		struct mt76_queue_entry *e = &q->entry[q->first];
 		struct sk_buff *iter;
 
+		smp_rmb();
+
 		if (!test_bit(MT76_STATE_MCU_RUNNING, &dev->phy.state)) {
 			__skb_put_zero(e->skb, 4);
 			err = __mt7663s_xmit_queue(dev, e->skb->data,
diff --git a/drivers/net/wireless/mediatek/mt76/sdio.c b/drivers/net/wireless/mediatek/mt76/sdio.c
index 0b6facb17ff7..a18d2896ee1f 100644
--- a/drivers/net/wireless/mediatek/mt76/sdio.c
+++ b/drivers/net/wireless/mediatek/mt76/sdio.c
@@ -256,6 +256,9 @@ mt76s_tx_queue_skb(struct mt76_dev *dev, struct mt76_queue *q,
 
 	q->entry[q->head].skb = tx_info.skb;
 	q->entry[q->head].buf_sz = len;
+
+	smp_wmb();
+
 	q->head = (q->head + 1) % q->ndesc;
 	q->queued++;
 
-- 
2.30.2