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From:   Lorenzo Bianconi <lorenzo@kernel.org>
To:     nbd@nbd.name
Cc:     linux-wireless@vger.kernel.org, lorenzo.bianconi@redhat.com,
        sean.wang@mediatek.com
Subject: [PATCH 01/19] mt76: mt7921: fix a race between mt7921_mcu_drv_pmctrl and mt7921_mcu_fw_pmctrl
Date:   Sun, 18 Apr 2021 18:45:27 +0200
Message-Id: <dee187bcde4b0410e09061e8ad786c3bd769497b.1618763001.git.lorenzo@kernel.org>
In-Reply-To: <cover.1618763000.git.lorenzo@kernel.org>
References: <cover.1618763000.git.lorenzo@kernel.org>
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Introduce a mutex in order to avoid a race between mt7921_mcu_drv_pmctrl and
mt7921_mcu_fw_pmctrl routines since they are run two independent works

Fixes: 1d8efc741df8 ("mt76: mt7921: introduce Runtime PM support")
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
---
 .../net/wireless/mediatek/mt76/mt76_connac.h  |  1 +
 .../net/wireless/mediatek/mt76/mt7921/init.c  |  1 +
 .../net/wireless/mediatek/mt76/mt7921/mcu.c   | 34 +++++++++++++------
 3 files changed, 26 insertions(+), 10 deletions(-)

diff --git a/drivers/net/wireless/mediatek/mt76/mt76_connac.h b/drivers/net/wireless/mediatek/mt76/mt76_connac.h
index b811f3c410a1..2b31c9794e92 100644
--- a/drivers/net/wireless/mediatek/mt76/mt76_connac.h
+++ b/drivers/net/wireless/mediatek/mt76/mt76_connac.h
@@ -54,6 +54,7 @@ struct mt76_connac_pm {
 
 	struct work_struct wake_work;
 	struct completion wake_cmpl;
+	struct mutex mutex;
 
 	struct delayed_work ps_work;
 	unsigned long last_activity;
diff --git a/drivers/net/wireless/mediatek/mt76/mt7921/init.c b/drivers/net/wireless/mediatek/mt76/mt7921/init.c
index eab6e2dcdb96..0b8a5a7f4362 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7921/init.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7921/init.c
@@ -222,6 +222,7 @@ int mt7921_register_device(struct mt7921_dev *dev)
 
 	INIT_DELAYED_WORK(&dev->pm.ps_work, mt7921_pm_power_save_work);
 	INIT_WORK(&dev->pm.wake_work, mt7921_pm_wake_work);
+	mutex_init(&dev->pm.mutex);
 	init_completion(&dev->pm.wake_cmpl);
 	spin_lock_init(&dev->pm.txq_lock);
 	set_bit(MT76_STATE_PM, &dev->mphy.state);
diff --git a/drivers/net/wireless/mediatek/mt76/mt7921/mcu.c b/drivers/net/wireless/mediatek/mt76/mt7921/mcu.c
index 14ba856de0b6..ea00f6b6af56 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7921/mcu.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7921/mcu.c
@@ -1267,9 +1267,11 @@ int mt7921_mcu_set_bss_pm(struct mt7921_dev *dev, struct ieee80211_vif *vif,
 int mt7921_mcu_drv_pmctrl(struct mt7921_dev *dev)
 {
 	struct mt76_phy *mphy = &dev->mt76.phy;
-	int i;
+	int i, err = 0;
 
-	if (!test_and_clear_bit(MT76_STATE_PM, &mphy->state))
+	mutex_lock(&dev->pm.mutex);
+
+	if (!test_bit(MT76_STATE_PM, &mphy->state))
 		goto out;
 
 	for (i = 0; i < MT7921_DRV_OWN_RETRY_COUNT; i++) {
@@ -1281,23 +1283,30 @@ int mt7921_mcu_drv_pmctrl(struct mt7921_dev *dev)
 
 	if (i == MT7921_DRV_OWN_RETRY_COUNT) {
 		dev_err(dev->mt76.dev, "driver own failed\n");
-		mt7921_reset(&dev->mt76);
-		return -EIO;
+		err = -EIO;
+		goto out;
 	}
+	clear_bit(MT76_STATE_PM, &mphy->state);
 
 out:
 	dev->pm.last_activity = jiffies;
+	mutex_unlock(&dev->pm.mutex);
 
-	return 0;
+	if (err)
+		mt7921_reset(&dev->mt76);
+
+	return err;
 }
 
 int mt7921_mcu_fw_pmctrl(struct mt7921_dev *dev)
 {
 	struct mt76_phy *mphy = &dev->mt76.phy;
-	int i;
+	int i, err = 0;
+
+	mutex_lock(&dev->pm.mutex);
 
 	if (test_and_set_bit(MT76_STATE_PM, &mphy->state))
-		return 0;
+		goto out;
 
 	for (i = 0; i < MT7921_DRV_OWN_RETRY_COUNT; i++) {
 		mt76_wr(dev, MT_CONN_ON_LPCTL, PCIE_LPCR_HOST_SET_OWN);
@@ -1308,11 +1317,16 @@ int mt7921_mcu_fw_pmctrl(struct mt7921_dev *dev)
 
 	if (i == MT7921_DRV_OWN_RETRY_COUNT) {
 		dev_err(dev->mt76.dev, "firmware own failed\n");
-		mt7921_reset(&dev->mt76);
-		return -EIO;
+		clear_bit(MT76_STATE_PM, &mphy->state);
+		err = -EIO;
 	}
+out:
+	mutex_unlock(&dev->pm.mutex);
 
-	return 0;
+	if (err)
+		mt7921_reset(&dev->mt76);
+
+	return err;
 }
 
 void
-- 
2.30.2