stmmac: dwmac-intel-plat: fix call balance of tx_clk handling routines

If the clock dwmac->tx_clk was not enabled in intel_eth_plat_probe,
it should not be disabled in any path.

Conversely, if it was enabled in intel_eth_plat_probe, it must be disabled
in all error paths to ensure proper cleanup.

Found by Linux Verification Center (linuxtesting.org) with Klever.

Fixes: 9efc9b2 ("net: stmmac: Add dwmac-intel-plat for GBE driver")
Signed-off-by: Vitalii Mordan <mordan@ispras.ru>
Link: https://patch.msgid.link/20241108173334.2973603-1-mordan@ispras.ru
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: vmordan

drivers/net/ethernet/stmicro/stmmac/dwmac-intel-plat.c

@@ -108,7 +108,12 @@ static int intel_eth_plat_probe(struct platform_device *pdev)
 			if (IS_ERR(dwmac->tx_clk))
 				return PTR_ERR(dwmac->tx_clk);
 
-			clk_prepare_enable(dwmac->tx_clk);
+			ret = clk_prepare_enable(dwmac->tx_clk);
+			if (ret) {
+				dev_err(&pdev->dev,
+					"Failed to enable tx_clk\n");
+				return ret;
+			}
 
 			/* Check and configure TX clock rate */
 			rate = clk_get_rate(dwmac->tx_clk);
@@ -119,7 +124,7 @@ static int intel_eth_plat_probe(struct platform_device *pdev)
 				if (ret) {
 					dev_err(&pdev->dev,
 						"Failed to set tx_clk\n");
-					return ret;
+					goto err_tx_clk_disable;
 				}
 			}
 		}
@@ -133,7 +138,7 @@ static int intel_eth_plat_probe(struct platform_device *pdev)
 			if (ret) {
 				dev_err(&pdev->dev,
 					"Failed to set clk_ptp_ref\n");
-				return ret;
+				goto err_tx_clk_disable;
 			}
 		}
 	}
@@ -149,20 +154,24 @@ static int intel_eth_plat_probe(struct platform_device *pdev)
 	}
 
 	ret = stmmac_dvr_probe(&pdev->dev, plat_dat, &stmmac_res);
-	if (ret) {
-		clk_disable_unprepare(dwmac->tx_clk);
-		return ret;
-	}
+	if (ret)
+		goto err_tx_clk_disable;
 
 	return 0;
+
+err_tx_clk_disable:
+	if (dwmac->data->tx_clk_en)
+		clk_disable_unprepare(dwmac->tx_clk);
+	return ret;
 }
 
 static void intel_eth_plat_remove(struct platform_device *pdev)
 {
 	struct intel_dwmac *dwmac = get_stmmac_bsp_priv(&pdev->dev);
 
 	stmmac_pltfr_remove(pdev);
-	clk_disable_unprepare(dwmac->tx_clk);
+	if (dwmac->data->tx_clk_en)
+		clk_disable_unprepare(dwmac->tx_clk);
 }
 
 static struct platform_driver intel_eth_plat_driver = {