[PATCH 11/23] wifi: mt76: mt7925: do not disable RX NAPI twice on unload

[Sean Wang]

From: Jacobs Wu <jacobs.wu at mediatek.com>

mt7925e_unregister_device() disables every RX NAPI and then calls
mt792x_dma_cleanup(), whose mt76_dma_cleanup() disables them again.
The second napi_disable() spins waiting for NAPI_STATE_SCHED, which the
first one already set and nobody will clear, so module unload hangs in
D state and the module refcount underflows to -1; only a reboot recovers.

Drop the redundant loop and leave the RX NAPI teardown to
mt76_dma_cleanup(), making driver hot-reload work again.

Co-developed-by: Sean Wang <sean.wang at mediatek.com>
Signed-off-by: Sean Wang <sean.wang at mediatek.com>
Signed-off-by: Jacobs Wu <jacobs.wu at mediatek.com>
---
 drivers/net/wireless/mediatek/mt76/mt7925/pci.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/net/wireless/mediatek/mt76/mt7925/pci.c b/drivers/net/wireless/mediatek/mt76/mt7925/pci.c
index 24585c992ff5..09153d624fd5 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7925/pci.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7925/pci.c
@@ -40,7 +40,6 @@ static int mt7925e_init_reset(struct mt792x_dev *dev)
 
 static void mt7925e_unregister_device(struct mt792x_dev *dev)
 {
-	int i;
 	struct mt76_connac_pm *pm = &dev->pm;
 	struct ieee80211_hw *hw = mt76_hw(dev);
 
@@ -50,8 +49,12 @@ static void mt7925e_unregister_device(struct mt792x_dev *dev)
 	cancel_work_sync(&dev->reset_work);
 	cancel_work_sync(&dev->init_work);
 	mt76_unregister_device(&dev->mt76);
-	mt76_for_each_q_rx(&dev->mt76, i)
-		napi_disable(&dev->mt76.napi[i]);
+	/* Do not disable the RX NAPIs here: mt76_dma_cleanup(), reached below
+	 * via mt792x_dma_cleanup(), disables them as part of the generic
+	 * teardown. Disabling twice makes the second napi_disable() wait
+	 * forever for NAPI_STATE_SCHED to clear, hanging module unload in D
+	 * state with the module refcount left at -1.
+	 */
 	cancel_delayed_work_sync(&pm->ps_work);
 	cancel_delayed_work_sync(&dev->mlo_pm_work);
 	cancel_work_sync(&pm->wake_work);
-- 
2.43.0