linux-kernel - [PATCH v2 net] net: phy: mscc: Add error check when __phy

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Date:   Tue, 10 May 2022 22:22:45 +0800
From:   Wan Jiabing <wanjiabing@...o.com>
To:     Andrew Lunn <andrew@...n.ch>,
        Heiner Kallweit <hkallweit1@...il.com>,
        Russell King <linux@...linux.org.uk>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Wan Jiabing <wanjiabing@...o.com>,
        Antoine Tenart <atenart@...nel.org>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH v2 net] net: phy: mscc: Add error check when __phy_read() failed

Calling __phy_read() might return a negative error code. Use 'int'
to declare variables which call __phy_read() and also add error check
for them.

The numerous callers of vsc8584_macsec_phy_read() don't expect it to
fail. So don't return the error code from __phy_read(), but also don't
return random values if it does fail.

Fixes: fa164e40c53b ("net: phy: mscc: split the driver into separate files")
Signed-off-by: Wan Jiabing <wanjiabing@...o.com>
---
Changelog:
v2:
- Sort variable declaration and add a detailed comment.
---
 drivers/net/phy/mscc/mscc_macsec.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/drivers/net/phy/mscc/mscc_macsec.c b/drivers/net/phy/mscc/mscc_macsec.c
index b7b2521c73fb..58ad11a697b6 100644
--- a/drivers/net/phy/mscc/mscc_macsec.c
+++ b/drivers/net/phy/mscc/mscc_macsec.c
@@ -22,9 +22,9 @@
 static u32 vsc8584_macsec_phy_read(struct phy_device *phydev,
 				   enum macsec_bank bank, u32 reg)
 {
-	u32 val, val_l = 0, val_h = 0;
+	int rc, val, val_l, val_h;
 	unsigned long deadline;
-	int rc;
+	u32 ret = 0;
 
 	rc = phy_select_page(phydev, MSCC_PHY_PAGE_MACSEC);
 	if (rc < 0)
@@ -47,15 +47,20 @@ static u32 vsc8584_macsec_phy_read(struct phy_device *phydev,
 	deadline = jiffies + msecs_to_jiffies(PROC_CMD_NCOMPLETED_TIMEOUT_MS);
 	do {
 		val = __phy_read(phydev, MSCC_EXT_PAGE_MACSEC_19);
+		if (val < 0)
+			goto failed;
 	} while (time_before(jiffies, deadline) && !(val & MSCC_PHY_MACSEC_19_CMD));
 
 	val_l = __phy_read(phydev, MSCC_EXT_PAGE_MACSEC_17);
 	val_h = __phy_read(phydev, MSCC_EXT_PAGE_MACSEC_18);
 
+	if (val_l > 0 && val_h > 0)
+		ret = (val_h << 16) | val_l;
+
 failed:
 	phy_restore_page(phydev, rc, rc);
 
-	return (val_h << 16) | val_l;
+	return ret;
 }
 
 static void vsc8584_macsec_phy_write(struct phy_device *phydev,
-- 
2.35.1