mt76: mt7921: fix a leftover race in runtime-pm

[ Upstream commit 591cdccebdd4d02eb46d400dea911136400cc567 ]

Fix a possible race in mt7921_pm_power_save_work() if rx/tx napi
schedules ps_work and we are currently accessing device register
on a different cpu.

Fixes: 1d8efc741df8 ("mt76: mt7921: introduce Runtime PM support")
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: Felix Fietkau <nbd@nbd.name>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/net/wireless/mediatek/mt76/mt7921/mac.c b/drivers/net/wireless/mediatek/mt76/mt7921/mac.c
index 04a288029c98eb29d4280ed974de26dbb43b73a7..c093920a597d1cdf3ec89e049b66a2dadb57e546 100644 (file)
--- a/drivers/net/wireless/mediatek/mt76/mt7921/mac.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7921/mac.c
@@ -1550,6 +1550,14 @@ void mt7921_pm_power_save_work(struct work_struct *work)
            test_bit(MT76_HW_SCHED_SCANNING, &mphy->state))
                goto out;
 
+       if (mutex_is_locked(&dev->mt76.mutex))
+               /* if mt76 mutex is held we should not put the device
+                * to sleep since we are currently accessing device
+                * register map. We need to wait for the next power_save
+                * trigger.
+                */
+               goto out;
+
        if (time_is_after_jiffies(dev->pm.last_activity + delta)) {
                delta = dev->pm.last_activity + delta - jiffies;
                goto out;