ethtool: Add generic options for tunables

This patch adds new ethtool cmd, ETHTOOL_GTUNABLE & ETHTOOL_STUNABLE for getting
tunable values from driver.

Add get_tunable and set_tunable to ethtool_ops. Driver implements these
functions for getting/setting tunable value.
Signed-off-by: Govindarajulu Varadarajan <_govind@gmx.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/ethtool.h

@@ -257,6 +257,10 @@ struct ethtool_ops {
 				     struct ethtool_eeprom *, u8 *);
 	int	(*get_eee)(struct net_device *, struct ethtool_eee *);
 	int	(*set_eee)(struct net_device *, struct ethtool_eee *);
+	int	(*get_tunable)(struct net_device *,
+			       const struct ethtool_tunable *, void *);
+	int	(*set_tunable)(struct net_device *,
+			       const struct ethtool_tunable *, const void *);
 
 
 };

include/uapi/linux/ethtool.h

@@ -209,6 +209,32 @@ struct ethtool_value {
 	__u32	data;
 };
 
+enum tunable_id {
+	ETHTOOL_ID_UNSPEC,
+	ETHTOOL_RX_COPYBREAK,
+};
+
+enum tunable_type_id {
+	ETHTOOL_TUNABLE_UNSPEC,
+	ETHTOOL_TUNABLE_U8,
+	ETHTOOL_TUNABLE_U16,
+	ETHTOOL_TUNABLE_U32,
+	ETHTOOL_TUNABLE_U64,
+	ETHTOOL_TUNABLE_STRING,
+	ETHTOOL_TUNABLE_S8,
+	ETHTOOL_TUNABLE_S16,
+	ETHTOOL_TUNABLE_S32,
+	ETHTOOL_TUNABLE_S64,
+};
+
+struct ethtool_tunable {
+	__u32	cmd;
+	__u32	id;
+	__u32	type_id;
+	__u32	len;
+	void	*data[0];
+};
+
 /**
  * struct ethtool_regs - hardware register dump
  * @cmd: Command number = %ETHTOOL_GREGS
@@ -1152,6 +1178,8 @@ enum ethtool_sfeatures_retval_bits {
 
 #define ETHTOOL_GRSSH		0x00000046 /* Get RX flow hash configuration */
 #define ETHTOOL_SRSSH		0x00000047 /* Set RX flow hash configuration */
+#define ETHTOOL_GTUNABLE	0x00000048 /* Get tunable configuration */
+#define ETHTOOL_STUNABLE	0x00000049 /* Set tunable configuration */
 
 /* compatibility with older code */
 #define SPARC_ETH_GSET		ETHTOOL_GSET

net/core/ethtool.c

@@ -1621,6 +1621,80 @@ static int ethtool_get_module_eeprom(struct net_device *dev,
 				      modinfo.eeprom_len);
 }
 
+static int ethtool_tunable_valid(const struct ethtool_tunable *tuna)
+{
+	switch (tuna->id) {
+	case ETHTOOL_RX_COPYBREAK:
+		if (tuna->len != sizeof(u32) ||
+		    tuna->type_id != ETHTOOL_TUNABLE_U32)
+			return -EINVAL;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static int ethtool_get_tunable(struct net_device *dev, void __user *useraddr)
+{
+	int ret;
+	struct ethtool_tunable tuna;
+	const struct ethtool_ops *ops = dev->ethtool_ops;
+	void *data;
+
+	if (!ops->get_tunable)
+		return -EOPNOTSUPP;
+	if (copy_from_user(&tuna, useraddr, sizeof(tuna)))
+		return -EFAULT;
+	ret = ethtool_tunable_valid(&tuna);
+	if (ret)
+		return ret;
+	data = kmalloc(tuna.len, GFP_USER);
+	if (!data)
+		return -ENOMEM;
+	ret = ops->get_tunable(dev, &tuna, data);
+	if (ret)
+		goto out;
+	useraddr += sizeof(tuna);
+	ret = -EFAULT;
+	if (copy_to_user(useraddr, data, tuna.len))
+		goto out;
+	ret = 0;
+
+out:
+	kfree(data);
+	return ret;
+}
+
+static int ethtool_set_tunable(struct net_device *dev, void __user *useraddr)
+{
+	int ret;
+	struct ethtool_tunable tuna;
+	const struct ethtool_ops *ops = dev->ethtool_ops;
+	void *data;
+
+	if (!ops->set_tunable)
+		return -EOPNOTSUPP;
+	if (copy_from_user(&tuna, useraddr, sizeof(tuna)))
+		return -EFAULT;
+	ret = ethtool_tunable_valid(&tuna);
+	if (ret)
+		return ret;
+	data = kmalloc(tuna.len, GFP_USER);
+	if (!data)
+		return -ENOMEM;
+	useraddr += sizeof(tuna);
+	ret = -EFAULT;
+	if (copy_from_user(data, useraddr, tuna.len))
+		goto out;
+	ret = ops->set_tunable(dev, &tuna, data);
+
+out:
+	kfree(data);
+	return ret;
+}
+
 /* The main entry point in this file.  Called from net/core/dev_ioctl.c */
 
 int dev_ethtool(struct net *net, struct ifreq *ifr)
@@ -1670,6 +1744,7 @@ int dev_ethtool(struct net *net, struct ifreq *ifr)
 	case ETHTOOL_GCHANNELS:
 	case ETHTOOL_GET_TS_INFO:
 	case ETHTOOL_GEEE:
+	case ETHTOOL_GTUNABLE:
 		break;
 	default:
 		if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
@@ -1857,6 +1932,12 @@ int dev_ethtool(struct net *net, struct ifreq *ifr)
 	case ETHTOOL_GMODULEEEPROM:
 		rc = ethtool_get_module_eeprom(dev, useraddr);
 		break;
+	case ETHTOOL_GTUNABLE:
+		rc = ethtool_get_tunable(dev, useraddr);
+		break;
+	case ETHTOOL_STUNABLE:
+		rc = ethtool_set_tunable(dev, useraddr);
+		break;
 	default:
 		rc = -EOPNOTSUPP;
 	}