net: core: Add ethool config option

Add this config option to reduce memory usage, if it was not necessary.

./ksize.sh net

before size: 739668 Bytes
after  size: 716596 Bytes
save   size: 23073  Bytes

Signed-off-by: David Wu <david.wu@rock-chips.com>
Change-Id: I3e3c515f6b88d2ebf04cb8976d061591caca201e

include/linux/ethtool.h

@@ -161,6 +161,7 @@ struct ethtool_link_ksettings {
 #define ethtool_link_ksettings_test_link_mode(ptr, name, mode)		\
 	test_bit(ETHTOOL_LINK_MODE_ ## mode ## _BIT, (ptr)->link_modes.name)
 
+#ifdef CONFIG_ETHTOOL
 extern int
 __ethtool_get_link_ksettings(struct net_device *dev,
 			     struct ethtool_link_ksettings *link_ksettings);
@@ -181,6 +182,33 @@ void ethtool_convert_legacy_u32_to_link_mode(unsigned long *dst,
 /* return false if src had higher bits set. lower bits always updated. */
 bool ethtool_convert_link_mode_to_legacy_u32(u32 *legacy_u32,
 				     const unsigned long *src);
+#else
+static inline int
+__ethtool_get_link_ksettings(struct net_device *dev,
+			     struct ethtool_link_ksettings *link_ksettings)
+{
+	return 0;
+}
+
+static inline
+void ethtool_intersect_link_masks(struct ethtool_link_ksettings *dst,
+				  struct ethtool_link_ksettings *src)
+{
+}
+
+static inline
+void ethtool_convert_legacy_u32_to_link_mode(unsigned long *dst,
+					     u32 legacy_u32)
+{
+}
+
+static inline
+bool ethtool_convert_link_mode_to_legacy_u32(u32 *legacy_u32,
+				     const unsigned long *src)
+{
+	return false;
+}
+#endif
 
 /**
  * struct ethtool_ops - optional netdev operations

net/Kconfig

@@ -309,6 +309,13 @@ config BPF_STREAM_PARSER
 	 It can be used to enforce socket policy, implement socket redirects,
 	 etc.
 
+config ETHTOOL
+	bool "enable ethtool"
+	default y
+	help
+	  This selects ethtool function, default is Y. If say N, ethtool function
+	  is not implemented.
+
 config NET_FLOW_LIMIT
 	bool
 	depends on RPS

net/core/Makefile

@@ -8,11 +8,12 @@ obj-y := sock.o request_sock.o skbuff.o datagram.o stream.o scm.o \
 
 obj-$(CONFIG_SYSCTL) += sysctl_net_core.o
 
-obj-y		     += dev.o ethtool.o dev_addr_lists.o dst.o netevent.o \
+obj-y		     += dev.o dev_addr_lists.o dst.o netevent.o \
 			neighbour.o rtnetlink.o utils.o link_watch.o filter.o \
 			sock_diag.o dev_ioctl.o tso.o sock_reuseport.o \
 			fib_notifier.o xdp.o
 
+obj-$(CONFIG_ETHTOOL) += ethtool.o
 obj-y += net-sysfs.o
 obj-$(CONFIG_PAGE_POOL) += page_pool.o
 obj-$(CONFIG_PROC_FS) += net-procfs.o

net/core/dev_ioctl.c

@@ -417,6 +417,7 @@ int dev_ioctl(struct net *net, unsigned int cmd, struct ifreq *ifr, bool *need_c
 			*colon = ':';
 		return ret;
 
+#ifdef CONFIG_ETHTOOL
 	case SIOCETHTOOL:
 		dev_load(net, ifr->ifr_name);
 		rtnl_lock();
@@ -425,6 +426,7 @@ int dev_ioctl(struct net *net, unsigned int cmd, struct ifreq *ifr, bool *need_c
 		if (colon)
 			*colon = ':';
 		return ret;
+#endif
 
 	/*
 	 *	These ioctl calls:

net/core/sysctl_net_core.c

@@ -243,6 +243,7 @@ static int proc_do_dev_weight(struct ctl_table *table, int write,
 	return ret;
 }
 
+#ifdef CONFIG_ETHTOOL
 static int proc_do_rss_key(struct ctl_table *table, int write,
 			   void __user *buffer, size_t *lenp, loff_t *ppos)
 {
@@ -254,6 +255,7 @@ static int proc_do_rss_key(struct ctl_table *table, int write,
 	fake_table.maxlen = sizeof(buf);
 	return proc_dostring(&fake_table, write, buffer, lenp, ppos);
 }
+#endif
 
 #ifdef CONFIG_BPF_JIT
 static int proc_dointvec_minmax_bpf_enable(struct ctl_table *table, int write,
@@ -368,6 +370,7 @@ static struct ctl_table net_core_table[] = {
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec
 	},
+#ifdef CONFIG_ETHTOOL
 	{
 		.procname	= "netdev_rss_key",
 		.data		= &netdev_rss_key,
@@ -375,6 +378,7 @@ static struct ctl_table net_core_table[] = {
 		.mode		= 0444,
 		.proc_handler	= proc_do_rss_key,
 	},
+#endif
 #ifdef CONFIG_BPF_JIT
 	{
 		.procname	= "bpf_jit_enable",