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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, Felix Fietkau <nbd@nbd.name>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.9 692/757] mt76: mt7915: do not do any work in napi poll after calling napi_complete_done()
Date:   Tue, 27 Oct 2020 14:55:42 +0100
Message-Id: <20201027135522.983863838@linuxfoundation.org>
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From: Felix Fietkau <nbd@nbd.name>

[ Upstream commit 38b04398c532e9bb9aa90fc07846ad0b0845fe94 ]

Fixes a race condition where multiple tx cleanup or sta poll tasks could run
in parallel.

Signed-off-by: Felix Fietkau <nbd@nbd.name>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/net/wireless/mediatek/mt76/mt7915/dma.c | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/drivers/net/wireless/mediatek/mt76/mt7915/dma.c b/drivers/net/wireless/mediatek/mt76/mt7915/dma.c
index a8832c5e60041..8a1ae08d9572e 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7915/dma.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7915/dma.c
@@ -95,16 +95,13 @@ static int mt7915_poll_tx(struct napi_struct *napi, int budget)
 	dev = container_of(napi, struct mt7915_dev, mt76.tx_napi);
 
 	mt7915_tx_cleanup(dev);
-
-	if (napi_complete_done(napi, 0))
-		mt7915_irq_enable(dev, MT_INT_TX_DONE_ALL);
-
-	mt7915_tx_cleanup(dev);
-
 	mt7915_mac_sta_poll(dev);
 
 	tasklet_schedule(&dev->mt76.tx_tasklet);
 
+	if (napi_complete_done(napi, 0))
+		mt7915_irq_enable(dev, MT_INT_TX_DONE_ALL);
+
 	return 0;
 }
 
-- 
2.25.1