[PATCH v2 net-next] net: ethernet: mtk_wed: fix possible deadlock if mtk_wed_wo_init fails

[Lorenzo Bianconi]

Introduce __mtk_wed_detach() in order to avoid a possible deadlock in
mtk_wed_attach routine if mtk_wed_wo_init fails.
Check wo pointer is properly allocated before running mtk_wed_wo_reset()
and mtk_wed_wo_deinit() in __mtk_wed_detach routine.
Honor mtk_wed_mcu_send_msg return value in mtk_wed_wo_reset().

Fixes: 4c5de09eb0d0 ("net: ethernet: mtk_wed: add configure wed wo support")
Signed-off-by: Lorenzo Bianconi <lorenzo at kernel.org>
---
Changes since v1:
- move wo pointer checks in __mtk_wed_detach()
---
 drivers/net/ethernet/mediatek/mtk_wed.c     | 30 ++++++++++++++-------
 drivers/net/ethernet/mediatek/mtk_wed_mcu.c |  3 +++
 2 files changed, 23 insertions(+), 10 deletions(-)

diff --git a/drivers/net/ethernet/mediatek/mtk_wed.c b/drivers/net/ethernet/mediatek/mtk_wed.c
index d041615b2bac..2ce9fbb1c66d 100644
--- a/drivers/net/ethernet/mediatek/mtk_wed.c
+++ b/drivers/net/ethernet/mediatek/mtk_wed.c
@@ -174,9 +174,10 @@ mtk_wed_wo_reset(struct mtk_wed_device *dev)
 	mtk_wdma_tx_reset(dev);
 	mtk_wed_reset(dev, MTK_WED_RESET_WED);
 
-	mtk_wed_mcu_send_msg(wo, MTK_WED_MODULE_ID_WO,
-			     MTK_WED_WO_CMD_CHANGE_STATE, &state,
-			     sizeof(state), false);
+	if (mtk_wed_mcu_send_msg(wo, MTK_WED_MODULE_ID_WO,
+				 MTK_WED_WO_CMD_CHANGE_STATE, &state,
+				 sizeof(state), false))
+		return;
 
 	if (readx_poll_timeout(mtk_wed_wo_read_status, dev, val,
 			       val == MTK_WED_WOIF_DISABLE_DONE,
@@ -576,12 +577,10 @@ mtk_wed_deinit(struct mtk_wed_device *dev)
 }
 
 static void
-mtk_wed_detach(struct mtk_wed_device *dev)
+__mtk_wed_detach(struct mtk_wed_device *dev)
 {
 	struct mtk_wed_hw *hw = dev->hw;
 
-	mutex_lock(&hw_lock);
-
 	mtk_wed_deinit(dev);
 
 	mtk_wdma_rx_reset(dev);
@@ -590,9 +589,11 @@ mtk_wed_detach(struct mtk_wed_device *dev)
 	mtk_wed_free_tx_rings(dev);
 
 	if (mtk_wed_get_rx_capa(dev)) {
-		mtk_wed_wo_reset(dev);
+		if (hw->wed_wo)
+			mtk_wed_wo_reset(dev);
 		mtk_wed_free_rx_rings(dev);
-		mtk_wed_wo_deinit(hw);
+		if (hw->wed_wo)
+			mtk_wed_wo_deinit(hw);
 	}
 
 	if (dev->wlan.bus_type == MTK_WED_BUS_PCIE) {
@@ -612,6 +613,13 @@ mtk_wed_detach(struct mtk_wed_device *dev)
 	module_put(THIS_MODULE);
 
 	hw->wed_dev = NULL;
+}
+
+static void
+mtk_wed_detach(struct mtk_wed_device *dev)
+{
+	mutex_lock(&hw_lock);
+	__mtk_wed_detach(dev);
 	mutex_unlock(&hw_lock);
 }
 
@@ -1490,8 +1498,10 @@ mtk_wed_attach(struct mtk_wed_device *dev)
 		ret = mtk_wed_wo_init(hw);
 	}
 out:
-	if (ret)
-		mtk_wed_detach(dev);
+	if (ret) {
+		dev_err(dev->hw->dev, "failed to attach wed device\n");
+		__mtk_wed_detach(dev);
+	}
 unlock:
 	mutex_unlock(&hw_lock);
 
diff --git a/drivers/net/ethernet/mediatek/mtk_wed_mcu.c b/drivers/net/ethernet/mediatek/mtk_wed_mcu.c
index f9539e6233c9..3dd02889d972 100644
--- a/drivers/net/ethernet/mediatek/mtk_wed_mcu.c
+++ b/drivers/net/ethernet/mediatek/mtk_wed_mcu.c
@@ -207,6 +207,9 @@ int mtk_wed_mcu_msg_update(struct mtk_wed_device *dev, int id, void *data,
 	if (dev->hw->version == 1)
 		return 0;
 
+	if (!wo)
+		return -ENODEV;
+
 	return mtk_wed_mcu_send_msg(wo, MTK_WED_MODULE_ID_WO, id, data, len,
 				    true);
 }
-- 
2.38.1