[PATCH net-next v2 1/2] net: sysfs: factor out link settings read

[Wang Zhan <wang.zhan@smartx.com>]

speed_show() and duplex_show() duplicate device validation, RTNL
locking and the link settings query. Move this common work to
sysfs_get_link_ksettings() so later locking changes stay in one place.

RTNL is released before calling sysfs_emit(). The lock only protects the
link settings query; formatting uses the local cmd copy, so the sysfs
output and error handling remain unchanged.

No functional changes.

Assisted-by: LLM
Signed-off-by: Wang Zhan <wang.zhan@smartx.com>
---
 net/core/net-sysfs.c | 97 ++++++++++++++++++++++----------------------
 1 file changed, 48 insertions(+), 49 deletions(-)

diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index 352173df75785..7bb8bbc1f71ea 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -118,6 +118,34 @@ static int sysfs_rtnl_lock(struct kobject *kobj, struct attribute *attr,
 	return ret;
 }
 
+static int sysfs_get_link_ksettings(struct device *dev,
+				    struct device_attribute *attr,
+				    struct ethtool_link_ksettings *cmd)
+{
+	struct net_device *netdev = to_net_dev(dev);
+	int ret;
+
+	/*
+	 * The check is also done in __ethtool_get_link_ksettings; this helps
+	 * returning early without hitting the locking section below.
+	 */
+	if (!netdev->ethtool_ops->get_link_ksettings)
+		return -EINVAL;
+
+	ret = sysfs_rtnl_lock(&dev->kobj, &attr->attr, netdev);
+	if (ret)
+		return ret;
+
+	ret = -EINVAL;
+	if (netif_running(netdev)) {
+		if (!__ethtool_get_link_ksettings(netdev, cmd))
+			ret = 0;
+	}
+
+	rtnl_unlock();
+	return ret;
+}
+
 /* use same locking rules as GIF* ioctl's */
 static ssize_t netdev_show(const struct device *dev,
 			   struct device_attribute *attr, char *buf,
@@ -332,70 +360,41 @@ static DEVICE_ATTR_RW(carrier);
 static ssize_t speed_show(struct device *dev,
 			  struct device_attribute *attr, char *buf)
 {
-	struct net_device *netdev = to_net_dev(dev);
-	int ret = -EINVAL;
-
-	/* The check is also done in __ethtool_get_link_ksettings; this helps
-	 * returning early without hitting the locking section below.
-	 */
-	if (!netdev->ethtool_ops->get_link_ksettings)
-		return ret;
+	struct ethtool_link_ksettings cmd;
+	int ret;
 
-	ret = sysfs_rtnl_lock(&dev->kobj, &attr->attr, netdev);
+	ret = sysfs_get_link_ksettings(dev, attr, &cmd);
 	if (ret)
 		return ret;
 
-	ret = -EINVAL;
-	if (netif_running(netdev)) {
-		struct ethtool_link_ksettings cmd;
-
-		if (!__ethtool_get_link_ksettings(netdev, &cmd))
-			ret = sysfs_emit(buf, fmt_dec, cmd.base.speed);
-	}
-	rtnl_unlock();
-	return ret;
+	return sysfs_emit(buf, fmt_dec, cmd.base.speed);
 }
 static DEVICE_ATTR_RO(speed);
 
 static ssize_t duplex_show(struct device *dev,
 			   struct device_attribute *attr, char *buf)
 {
-	struct net_device *netdev = to_net_dev(dev);
-	int ret = -EINVAL;
-
-	/* The check is also done in __ethtool_get_link_ksettings; this helps
-	 * returning early without hitting the locking section below.
-	 */
-	if (!netdev->ethtool_ops->get_link_ksettings)
-		return ret;
+	struct ethtool_link_ksettings cmd;
+	const char *duplex;
+	int ret;
 
-	ret = sysfs_rtnl_lock(&dev->kobj, &attr->attr, netdev);
+	ret = sysfs_get_link_ksettings(dev, attr, &cmd);
 	if (ret)
 		return ret;
 
-	ret = -EINVAL;
-	if (netif_running(netdev)) {
-		struct ethtool_link_ksettings cmd;
-
-		if (!__ethtool_get_link_ksettings(netdev, &cmd)) {
-			const char *duplex;
-
-			switch (cmd.base.duplex) {
-			case DUPLEX_HALF:
-				duplex = "half";
-				break;
-			case DUPLEX_FULL:
-				duplex = "full";
-				break;
-			default:
-				duplex = "unknown";
-				break;
-			}
-			ret = sysfs_emit(buf, "%s\n", duplex);
-		}
+	switch (cmd.base.duplex) {
+	case DUPLEX_HALF:
+		duplex = "half";
+		break;
+	case DUPLEX_FULL:
+		duplex = "full";
+		break;
+	default:
+		duplex = "unknown";
+		break;
 	}
-	rtnl_unlock();
-	return ret;
+
+	return sysfs_emit(buf, "%s\n", duplex);
 }
 static DEVICE_ATTR_RO(duplex);
 
-- 
2.47.3