net: ethtool: provide shims for stats aggregation helpers when CONFIG_ETHTOOL_NETLINK=n

ethtool_aggregate_*_stats() are implemented in net/ethtool/stats.c, a
file which is compiled out when CONFIG_ETHTOOL_NETLINK=n. In order to
avoid adding Kbuild dependencies from drivers (which call these helpers)
on CONFIG_ETHTOOL_NETLINK, let's add some shim definitions which simply
make the helpers dead code.

This means the function prototypes should have been located in
include/linux/ethtool_netlink.h rather than include/linux/ethtool.h.

Fixes: 449c5459 ("net: ethtool: add helpers for aggregate statistics")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
Link: https://lore.kernel.org/r/20230125110214.4127759-1-vladimir.oltean@nxp.comSigned-off-by: Paolo Abeni <pabeni@redhat.com>

drivers/net/ethernet/mscc/ocelot_stats.c

@@ -4,6 +4,7 @@
  * Copyright (c) 2017 Microsemi Corporation
  * Copyright 2022 NXP
  */
+#include <linux/ethtool_netlink.h>
 #include <linux/spinlock.h>
 #include <linux/mutex.h>
 #include <linux/workqueue.h>

include/linux/ethtool.h

@@ -991,17 +991,6 @@ int ethtool_get_phc_vclocks(struct net_device *dev, int **vclock_index);
 u32 ethtool_op_get_link(struct net_device *dev);
 int ethtool_op_get_ts_info(struct net_device *dev, struct ethtool_ts_info *eti);
 
-void ethtool_aggregate_mac_stats(struct net_device *dev,
-				 struct ethtool_eth_mac_stats *mac_stats);
-void ethtool_aggregate_phy_stats(struct net_device *dev,
-				 struct ethtool_eth_phy_stats *phy_stats);
-void ethtool_aggregate_ctrl_stats(struct net_device *dev,
-				  struct ethtool_eth_ctrl_stats *ctrl_stats);
-void ethtool_aggregate_pause_stats(struct net_device *dev,
-				   struct ethtool_pause_stats *pause_stats);
-void ethtool_aggregate_rmon_stats(struct net_device *dev,
-				  struct ethtool_rmon_stats *rmon_stats);
-
 /**
  * ethtool_mm_frag_size_add_to_min - Translate (standard) additional fragment
  *	size expressed as multiplier into (absolute) minimum fragment size

include/linux/ethtool_netlink.h

@@ -29,6 +29,17 @@ int ethnl_cable_test_amplitude(struct phy_device *phydev, u8 pair, s16 mV);
 int ethnl_cable_test_pulse(struct phy_device *phydev, u16 mV);
 int ethnl_cable_test_step(struct phy_device *phydev, u32 first, u32 last,
 			  u32 step);
+void ethtool_aggregate_mac_stats(struct net_device *dev,
+				 struct ethtool_eth_mac_stats *mac_stats);
+void ethtool_aggregate_phy_stats(struct net_device *dev,
+				 struct ethtool_eth_phy_stats *phy_stats);
+void ethtool_aggregate_ctrl_stats(struct net_device *dev,
+				  struct ethtool_eth_ctrl_stats *ctrl_stats);
+void ethtool_aggregate_pause_stats(struct net_device *dev,
+				   struct ethtool_pause_stats *pause_stats);
+void ethtool_aggregate_rmon_stats(struct net_device *dev,
+				  struct ethtool_rmon_stats *rmon_stats);
+
 #else
 static inline int ethnl_cable_test_alloc(struct phy_device *phydev, u8 cmd)
 {
@@ -70,5 +81,36 @@ static inline int ethnl_cable_test_step(struct phy_device *phydev, u32 first,
 {
 	return -EOPNOTSUPP;
 }
+
+static inline void
+ethtool_aggregate_mac_stats(struct net_device *dev,
+			    struct ethtool_eth_mac_stats *mac_stats)
+{
+}
+
+static inline void
+ethtool_aggregate_phy_stats(struct net_device *dev,
+			    struct ethtool_eth_phy_stats *phy_stats)
+{
+}
+
+static inline void
+ethtool_aggregate_ctrl_stats(struct net_device *dev,
+			     struct ethtool_eth_ctrl_stats *ctrl_stats)
+{
+}
+
+static inline void
+ethtool_aggregate_pause_stats(struct net_device *dev,
+			      struct ethtool_pause_stats *pause_stats)
+{
+}
+
+static inline void
+ethtool_aggregate_rmon_stats(struct net_device *dev,
+			     struct ethtool_rmon_stats *rmon_stats)
+{
+}
+
 #endif /* IS_ENABLED(CONFIG_ETHTOOL_NETLINK) */
 #endif /* _LINUX_ETHTOOL_NETLINK_H_ */