openwrt/target/linux/generic/backport-6.1/730-17-v6.3-net-ethernet-mtk_wed-fix-possible-deadlock-if-mtk_we.patch

From: Lorenzo Bianconi <lorenzo@kernel.org>
Date: Wed, 7 Dec 2022 15:04:55 +0100
Subject: [PATCH] net: ethernet: mtk_wed: fix possible deadlock if
 mtk_wed_wo_init fails

Introduce __mtk_wed_detach() in order to avoid a deadlock in
mtk_wed_attach routine if mtk_wed_wo_init fails since both
mtk_wed_attach and mtk_wed_detach run holding hw_lock mutex.

Fixes: 4c5de09eb0d0 ("net: ethernet: mtk_wed: add configure wed wo support")
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---

--- a/drivers/net/ethernet/mediatek/mtk_wed.c
+++ b/drivers/net/ethernet/mediatek/mtk_wed.c
@@ -619,12 +619,10 @@ mtk_wed_deinit(struct mtk_wed_device *de
 }
 
 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);
@@ -657,6 +655,13 @@ mtk_wed_detach(struct mtk_wed_device *de
 	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);
 }
 
@@ -1538,8 +1543,10 @@ mtk_wed_attach(struct mtk_wed_device *de
 		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);