netdev - [PATCH net-next] net: usb: sr9700: only store little-endian values in _

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Message-Id: <20241016-blackbird-le16-v1-1-97ba8de6b38f@kernel.org>
Date: Wed, 16 Oct 2024 15:31:14 +0100
From: Simon Horman <horms@...nel.org>
To: "David S. Miller" <davem@...emloft.net>, 
 Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, 
 Paolo Abeni <pabeni@...hat.com>
Cc: linux-usb@...r.kernel.org, netdev@...r.kernel.org
Subject: [PATCH net-next] net: usb: sr9700: only store little-endian values
 in __le16 variable

In sr_mdio_read() the local variable res is used to store both
little-endian and host byte order values. This prevents Sparse
from helping us by flagging when endian miss matches occur - the
detection process hinges on the type of variables matching the
byte order of values stored in them.

Address this by adding a new local variable, word, to store little-endian
values; change the type of res to int, and use it to store host-byte
order values.

Flagged by Sparse as:

.../sr9700.c:205:21: warning: incorrect type in assignment (different base types)
.../sr9700.c:205:21:    expected restricted __le16 [addressable] [usertype] res
.../sr9700.c:205:21:    got int
.../sr9700.c:207:21: warning: incorrect type in assignment (different base types)
.../sr9700.c:207:21:    expected restricted __le16 [addressable] [usertype] res
.../sr9700.c:207:21:    got int
.../sr9700.c:212:16: warning: incorrect type in return expression (different base types)
.../sr9700.c:212:16:    expected int
.../sr9700.c:212:16:    got restricted __le16 [addressable] [usertype] res

Compile tested only.
No functional change intended.

Signed-off-by: Simon Horman <horms@...nel.org>
---
 drivers/net/usb/sr9700.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/net/usb/sr9700.c b/drivers/net/usb/sr9700.c
index cb7d2f798fb4..091bc2aca7e8 100644
--- a/drivers/net/usb/sr9700.c
+++ b/drivers/net/usb/sr9700.c
@@ -177,9 +177,9 @@ static int sr9700_get_eeprom(struct net_device *netdev,
 static int sr_mdio_read(struct net_device *netdev, int phy_id, int loc)
 {
 	struct usbnet *dev = netdev_priv(netdev);
-	__le16 res;
+	int err, res;
+	__le16 word;
 	int rc = 0;
-	int err;

 	if (phy_id) {
 		netdev_dbg(netdev, "Only internal phy supported\n");
@@ -197,14 +197,14 @@ static int sr_mdio_read(struct net_device *netdev, int phy_id, int loc)
 		if (value & NSR_LINKST)
 			rc = 1;
 	}
-	err = sr_share_read_word(dev, 1, loc, &res);
+	err = sr_share_read_word(dev, 1, loc, &word);
 	if (err < 0)
 		return err;

 	if (rc == 1)
-		res = le16_to_cpu(res) | BMSR_LSTATUS;
+		res = le16_to_cpu(word) | BMSR_LSTATUS;
 	else
-		res = le16_to_cpu(res) & ~BMSR_LSTATUS;
+		res = le16_to_cpu(word) & ~BMSR_LSTATUS;

 	netdev_dbg(netdev, "sr_mdio_read() phy_id=0x%02x, loc=0x%02x, returns=0x%04x\n",
 		   phy_id, loc, res);