netdev - [PATCH v3] net: stmmac: restructure the error path of stmmac_probe_config

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Message-Id: <20241219024119.2017012-1-joe@pf.is.s.u-tokyo.ac.jp>
Date: Thu, 19 Dec 2024 11:41:19 +0900
From: Joe Hattori <joe@...is.s.u-tokyo.ac.jp>
To: alexandre.torgue@...s.st.com,
	joabreu@...opsys.com,
	andrew+netdev@...n.ch,
	davem@...emloft.net,
	edumazet@...gle.com,
	kuba@...nel.org,
	pabeni@...hat.com,
	mcoquelin.stm32@...il.com
Cc: netdev@...r.kernel.org,
	dan.carpenter@...aro.org,
	Joe Hattori <joe@...is.s.u-tokyo.ac.jp>
Subject: [PATCH v3] net: stmmac: restructure the error path of stmmac_probe_config_dt()

Current implementation of stmmac_probe_config_dt() does not release the
OF node reference obtained by of_parse_phandle() in some error paths.
The problem is that some error paths call stmmac_remove_config_dt() to
clean up but others use and unwind ladder.  These two types of error
handling have not kept in sync and have been a recurring source of bugs.
Re-write the error handling in stmmac_probe_config_dt() to use an unwind
ladder. Consequently, stmmac_remove_config_dt() is not needed anymore,
thus remove it.

This bug was found by an experimental verification tool that I am
developing.

Fixes: 4838a5405028 ("net: stmmac: Fix wrapper drivers not detecting PHY")
Signed-off-by: Joe Hattori <joe@...is.s.u-tokyo.ac.jp>
---
Changes in v3:
- Switch to the unwind ladder and remove stmmac_remove_config_dt().
- Merge the patches into one.

Changes in v2:
- Call of_node_put() instead of stmmac_remove_config_dt() when
  stmmac_mdio_setup() fails.
- Split the patch into two.
---
 .../ethernet/stmicro/stmmac/stmmac_platform.c | 43 ++++++++-----------
 1 file changed, 17 insertions(+), 26 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
index 3ac32444e492..dc9884130b91 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
@@ -405,22 +405,6 @@ static int stmmac_of_get_mac_mode(struct device_node *np)
 	return -ENODEV;
 }
 
-/**
- * stmmac_remove_config_dt - undo the effects of stmmac_probe_config_dt()
- * @pdev: platform_device structure
- * @plat: driver data platform structure
- *
- * Release resources claimed by stmmac_probe_config_dt().
- */
-static void stmmac_remove_config_dt(struct platform_device *pdev,
-				    struct plat_stmmacenet_data *plat)
-{
-	clk_disable_unprepare(plat->stmmac_clk);
-	clk_disable_unprepare(plat->pclk);
-	of_node_put(plat->phy_node);
-	of_node_put(plat->mdio_node);
-}
-
 /**
  * stmmac_probe_config_dt - parse device-tree driver parameters
  * @pdev: platform_device structure
@@ -490,8 +474,10 @@ stmmac_probe_config_dt(struct platform_device *pdev, u8 *mac)
 		dev_warn(&pdev->dev, "snps,phy-addr property is deprecated\n");
 
 	rc = stmmac_mdio_setup(plat, np, &pdev->dev);
-	if (rc)
-		return ERR_PTR(rc);
+	if (rc) {
+		ret = ERR_PTR(rc);
+		goto error_put_phy;
+	}
 
 	of_property_read_u32(np, "tx-fifo-depth", &plat->tx_fifo_size);
 
@@ -581,8 +567,8 @@ stmmac_probe_config_dt(struct platform_device *pdev, u8 *mac)
 	dma_cfg = devm_kzalloc(&pdev->dev, sizeof(*dma_cfg),
 			       GFP_KERNEL);
 	if (!dma_cfg) {
-		stmmac_remove_config_dt(pdev, plat);
-		return ERR_PTR(-ENOMEM);
+		ret = ERR_PTR(-ENOMEM);
+		goto error_put_mdio;
 	}
 	plat->dma_cfg = dma_cfg;
 
@@ -610,8 +596,8 @@ stmmac_probe_config_dt(struct platform_device *pdev, u8 *mac)
 
 	rc = stmmac_mtl_setup(pdev, plat);
 	if (rc) {
-		stmmac_remove_config_dt(pdev, plat);
-		return ERR_PTR(rc);
+		ret = ERR_PTR(rc);
+		goto error_put_mdio;
 	}
 
 	/* clock setup */
@@ -663,6 +649,10 @@ stmmac_probe_config_dt(struct platform_device *pdev, u8 *mac)
 	clk_disable_unprepare(plat->pclk);
 error_pclk_get:
 	clk_disable_unprepare(plat->stmmac_clk);
+error_put_mdio:
+	of_node_put(plat->mdio_node);
+error_put_phy:
+	of_node_put(plat->phy_node);
 
 	return ret;
 }
@@ -671,16 +661,17 @@ static void devm_stmmac_remove_config_dt(void *data)
 {
 	struct plat_stmmacenet_data *plat = data;
 
-	/* Platform data argument is unused */
-	stmmac_remove_config_dt(NULL, plat);
+	clk_disable_unprepare(plat->stmmac_clk);
+	clk_disable_unprepare(plat->pclk);
+	of_node_put(plat->mdio_node);
+	of_node_put(plat->phy_node);
 }
 
 /**
  * devm_stmmac_probe_config_dt
  * @pdev: platform_device structure
  * @mac: MAC address to use
- * Description: Devres variant of stmmac_probe_config_dt(). Does not require
- * the user to call stmmac_remove_config_dt() at driver detach.
+ * Description: Devres variant of stmmac_probe_config_dt().
  */
 struct plat_stmmacenet_data *
 devm_stmmac_probe_config_dt(struct platform_device *pdev, u8 *mac)
-- 
2.34.1