marvell: pxa168_eth: fix call balance of pep->clk handling routines

If the clock pep->clk was not enabled in pxa168_eth_probe,
it should not be disabled in any path.

Conversely, if it was enabled in pxa168_eth_probe, it must be disabled
in all error paths to ensure proper cleanup.

Use the devm_clk_get_enabled helper function to ensure proper call balance
for pep->clk.

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

Fixes: a49f37e ("net: add Fast Ethernet driver for PXA168.")
Signed-off-by: Vitalii Mordan <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Paolo Abeni <[email protected]>

Author: vmordan

drivers/net/ethernet/marvell/pxa168_eth.c

@@ -1394,18 +1394,15 @@ static int pxa168_eth_probe(struct platform_device *pdev)
 
 	printk(KERN_NOTICE "PXA168 10/100 Ethernet Driver\n");
 
-	clk = devm_clk_get(&pdev->dev, NULL);
+	clk = devm_clk_get_enabled(&pdev->dev, NULL);
 	if (IS_ERR(clk)) {
-		dev_err(&pdev->dev, "Fast Ethernet failed to get clock\n");
+		dev_err(&pdev->dev, "Fast Ethernet failed to get and enable clock\n");
 		return -ENODEV;
 	}
-	clk_prepare_enable(clk);
 
 	dev = alloc_etherdev(sizeof(struct pxa168_eth_private));
-	if (!dev) {
-		err = -ENOMEM;
-		goto err_clk;
-	}
+	if (!dev)
+		return -ENOMEM;
 
 	platform_set_drvdata(pdev, dev);
 	pep = netdev_priv(dev);
@@ -1523,8 +1520,6 @@ static int pxa168_eth_probe(struct platform_device *pdev)
 	mdiobus_free(pep->smi_bus);
 err_netdev:
 	free_netdev(dev);
-err_clk:
-	clk_disable_unprepare(clk);
 	return err;
 }
 
@@ -1542,7 +1537,6 @@ static void pxa168_eth_remove(struct platform_device *pdev)
 	if (dev->phydev)
 		phy_disconnect(dev->phydev);
 
-	clk_disable_unprepare(pep->clk);
 	mdiobus_unregister(pep->smi_bus);
 	mdiobus_free(pep->smi_bus);
 	unregister_netdev(dev);