ethtool: Implement ethtool_puts()

Use strscpy() to implement ethtool_puts().

Functionally the same as ethtool_sprintf() when it's used with two
arguments or with just "%s" format specifier.
Signed-off-by: Justin Stitt <justinstitt@google.com>
Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Madhuri Sripada <madhuri.sripada@microchip.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/ethtool.h

@@ -1061,6 +1061,19 @@ int ethtool_get_ts_info_by_layer(struct net_device *dev, struct ethtool_ts_info
  */
 extern __printf(2, 3) void ethtool_sprintf(u8 **data, const char *fmt, ...);
 
+/**
+ * ethtool_puts - Write string to ethtool string data
+ * @data: Pointer to a pointer to the start of string to update
+ * @str: String to write
+ *
+ * Write string to *data without a trailing newline. Update *data
+ * to point at start of next string.
+ *
+ * Prefer this function to ethtool_sprintf() when given only
+ * two arguments or if @fmt is just "%s".
+ */
+extern void ethtool_puts(u8 **data, const char *str);
+
 /* Link mode to forced speed capabilities maps */
 struct ethtool_forced_speed_map {
 	u32		speed;

net/ethtool/ioctl.c

@@ -1994,6 +1994,13 @@ __printf(2, 3) void ethtool_sprintf(u8 **data, const char *fmt, ...)
 }
 EXPORT_SYMBOL(ethtool_sprintf);
 
+void ethtool_puts(u8 **data, const char *str)
+{
+	strscpy(*data, str, ETH_GSTRING_LEN);
+	*data += ETH_GSTRING_LEN;
+}
+EXPORT_SYMBOL(ethtool_puts);
+
 static int ethtool_phys_id(struct net_device *dev, void __user *useraddr)
 {
 	struct ethtool_value id;