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

[Lorenzo Bianconi <lorenzo@kernel.org>]

Introduce __mtk_wed_detach() in order to avoid a possible deadlock in
mtk_wed_attach routine if mtk_wed_wo_init fails.

Fixes: 4c5de09eb0d0 ("net: ethernet: mtk_wed: add configure wed wo support")
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
---
 drivers/net/ethernet/mediatek/mtk_wed.c     | 24 ++++++++++++++-------
 drivers/net/ethernet/mediatek/mtk_wed_mcu.c | 10 ++++++---
 drivers/net/ethernet/mediatek/mtk_wed_wo.c  |  3 +++
 3 files changed, 26 insertions(+), 11 deletions(-)

diff --git a/drivers/net/ethernet/mediatek/mtk_wed.c b/drivers/net/ethernet/mediatek/mtk_wed.c
index d041615b2bac..6352abd4157e 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);
@@ -612,6 +611,13 @@ 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 +1496,10 @@ 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..b084009a32f9 100644
--- a/drivers/net/ethernet/mediatek/mtk_wed_mcu.c
+++ b/drivers/net/ethernet/mediatek/mtk_wed_mcu.c
@@ -176,6 +176,9 @@ int mtk_wed_mcu_send_msg(struct mtk_wed_wo *wo, int id, int cmd,
 	u16 seq;
 	int ret;
 
+	if (!wo)
+		return -ENODEV;
+
 	skb = mtk_wed_mcu_msg_alloc(data, len);
 	if (!skb)
 		return -ENOMEM;
@@ -202,13 +205,14 @@ int mtk_wed_mcu_send_msg(struct mtk_wed_wo *wo, int id, int cmd,
 int mtk_wed_mcu_msg_update(struct mtk_wed_device *dev, int id, void *data,
 			   int len)
 {
-	struct mtk_wed_wo *wo = dev->hw->wed_wo;
+	if (!dev->hw || !dev->hw->wed_wo)
+		return 0;
 
 	if (dev->hw->version == 1)
 		return 0;
 
-	return mtk_wed_mcu_send_msg(wo, MTK_WED_MODULE_ID_WO, id, data, len,
-				    true);
+	return mtk_wed_mcu_send_msg(dev->hw->wed_wo, MTK_WED_MODULE_ID_WO, id,
+				    data, len, true);
 }
 
 static int
diff --git a/drivers/net/ethernet/mediatek/mtk_wed_wo.c b/drivers/net/ethernet/mediatek/mtk_wed_wo.c
index a219da85f4db..92440d62e01c 100644
--- a/drivers/net/ethernet/mediatek/mtk_wed_wo.c
+++ b/drivers/net/ethernet/mediatek/mtk_wed_wo.c
@@ -464,6 +464,9 @@ mtk_wed_wo_hardware_init(struct mtk_wed_wo *wo)
 static void
 mtk_wed_wo_hw_deinit(struct mtk_wed_wo *wo)
 {
+	if (!wo)
+		return;
+
 	/* disable interrupts */
 	mtk_wed_wo_set_isr(wo, 0);
 
-- 
2.38.1