linux-kernel - [PATCH 6.0 276/862] wifi: mt76: mt7921s: fix race issue between reset and suspend/resume

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Date:   Wed, 19 Oct 2022 10:26:03 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, YN Chen <YN.Chen@...iatek.com>,
        Sean Wang <sean.wang@...iatek.com>,
        Felix Fietkau <nbd@....name>, Sasha Levin <sashal@...nel.org>
Subject: [PATCH 6.0 276/862] wifi: mt76: mt7921s: fix race issue between reset and suspend/resume

From: Sean Wang <sean.wang@...iatek.com>

[ Upstream commit e86f10e6809add9132ecc2c6b3184ed59db7ca71 ]

It is unexpected that the reset work is running simultaneously with
the suspend or resume context and it is possible that reset work is still
running even after mt7921 is suspended if we don't fix the race issue.

Thus, the suspend procedure should be waiting until the reset is completed
at the beginning and ignore the subsequent the reset requests.

In case there is an error that happens during either suspend or resume
handler, we will schedule a reset task to recover the error before
returning the error code to ensure we can immediately fix the error there.

Fixes: ca74b9b907f9 ("mt76: mt7921s: add reset support")
Co-developed-by: YN Chen <YN.Chen@...iatek.com>
Signed-off-by: YN Chen <YN.Chen@...iatek.com>
Signed-off-by: Sean Wang <sean.wang@...iatek.com>
Signed-off-by: Felix Fietkau <nbd@....name>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/net/wireless/mediatek/mt76/mt7921/sdio.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/drivers/net/wireless/mediatek/mt76/mt7921/sdio.c b/drivers/net/wireless/mediatek/mt76/mt7921/sdio.c
index 487acd6e2be8..2face849fb4f 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7921/sdio.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7921/sdio.c
@@ -206,6 +206,7 @@ static int mt7921s_suspend(struct device *__dev)
 	pm->suspended = true;
 	set_bit(MT76_STATE_SUSPEND, &mdev->phy.state);
 
+	flush_work(&dev->reset_work);
 	cancel_delayed_work_sync(&pm->ps_work);
 	cancel_work_sync(&pm->wake_work);
 
@@ -261,6 +262,9 @@ static int mt7921s_suspend(struct device *__dev)
 	clear_bit(MT76_STATE_SUSPEND, &mdev->phy.state);
 	pm->suspended = false;
 
+	if (err < 0)
+		mt7921_reset(&dev->mt76);
+
 	return err;
 }
 
@@ -276,7 +280,7 @@ static int mt7921s_resume(struct device *__dev)
 
 	err = mt7921_mcu_drv_pmctrl(dev);
 	if (err < 0)
-		return err;
+		goto failed;
 
 	mt76_worker_enable(&mdev->tx_worker);
 	mt76_worker_enable(&mdev->sdio.txrx_worker);
@@ -288,11 +292,12 @@ static int mt7921s_resume(struct device *__dev)
 		mt76_connac_mcu_set_deep_sleep(mdev, false);
 
 	err = mt76_connac_mcu_set_hif_suspend(mdev, false);
-	if (err)
-		return err;
-
+failed:
 	pm->suspended = false;
 
+	if (err < 0)
+		mt7921_reset(&dev->mt76);
+
 	return err;
 }
 
-- 
2.35.1