linux-kernel - [PATCH 5.16 0352/1039] mt76: mt7921: fix a possible race enabling/disabling runtime-pm

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Date:   Mon, 24 Jan 2022 19:35:41 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Deren Wu <deren.wu@...iatek.com>,
        Lorenzo Bianconi <lorenzo@...nel.org>,
        Kalle Valo <kvalo@...nel.org>, Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.16 0352/1039] mt76: mt7921: fix a possible race enabling/disabling runtime-pm

From: Lorenzo Bianconi <lorenzo@...nel.org>

[ Upstream commit d430dffbe9dd30759f3c64b65bf85b0245c8d8ab ]

Fix a possible race enabling/disabling runtime-pm between
mt7921_pm_set() and mt7921_poll_rx() since mt7921_pm_wake_work()
always schedules rx-napi callback and it will trigger
mt7921_pm_power_save_work routine putting chip to in low-power state
during mt7921_pm_set processing.

Suggested-by: Deren Wu <deren.wu@...iatek.com>
Tested-by: Deren Wu <deren.wu@...iatek.com>
Fixes: 1d8efc741df8 ("mt76: mt7921: introduce Runtime PM support")
Signed-off-by: Lorenzo Bianconi <lorenzo@...nel.org>
Signed-off-by: Kalle Valo <kvalo@...nel.org>
Link: https://lore.kernel.org/r/0f3e075a2033dc05f09dab4059e5be8cbdccc239.1640094847.git.lorenzo@kernel.org
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/net/wireless/mediatek/mt76/mt76_connac_mac.c |  3 ---
 drivers/net/wireless/mediatek/mt76/mt7921/debugfs.c  | 12 +++++++++---
 2 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/drivers/net/wireless/mediatek/mt76/mt76_connac_mac.c b/drivers/net/wireless/mediatek/mt76/mt76_connac_mac.c
index af43bcb545781..306e9eaea9177 100644
--- a/drivers/net/wireless/mediatek/mt76/mt76_connac_mac.c
+++ b/drivers/net/wireless/mediatek/mt76/mt76_connac_mac.c
@@ -7,9 +7,6 @@ int mt76_connac_pm_wake(struct mt76_phy *phy, struct mt76_connac_pm *pm)
 {
 	struct mt76_dev *dev = phy->dev;
 
-	if (!pm->enable)
-		return 0;
-
 	if (mt76_is_usb(dev))
 		return 0;
 
diff --git a/drivers/net/wireless/mediatek/mt76/mt7921/debugfs.c b/drivers/net/wireless/mediatek/mt76/mt7921/debugfs.c
index 7cdfdf83529f6..86fd7292b229f 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7921/debugfs.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7921/debugfs.c
@@ -276,7 +276,7 @@ mt7921_pm_set(void *data, u64 val)
 	struct mt7921_dev *dev = data;
 	struct mt76_connac_pm *pm = &dev->pm;
 
-	mt7921_mutex_acquire(dev);
+	mutex_lock(&dev->mt76.mutex);
 
 	if (val == pm->enable)
 		goto out;
@@ -285,7 +285,11 @@ mt7921_pm_set(void *data, u64 val)
 		pm->stats.last_wake_event = jiffies;
 		pm->stats.last_doze_event = jiffies;
 	}
-	pm->enable = val;
+	/* make sure the chip is awake here and ps_work is scheduled
+	 * just at end of the this routine.
+	 */
+	pm->enable = false;
+	mt76_connac_pm_wake(&dev->mphy, pm);
 
 	ieee80211_iterate_active_interfaces(mt76_hw(dev),
 					    IEEE80211_IFACE_ITER_RESUME_ALL,
@@ -293,8 +297,10 @@ mt7921_pm_set(void *data, u64 val)
 
 	mt76_connac_mcu_set_deep_sleep(&dev->mt76, pm->ds_enable);
 
+	pm->enable = val;
+	mt76_connac_power_save_sched(&dev->mphy, pm);
 out:
-	mt7921_mutex_release(dev);
+	mutex_unlock(&dev->mt76.mutex);
 
 	return 0;
 }
-- 
2.34.1