linux(4): Move use_real_names knob to the linux.c

MI linux.[c|h] are the module independent in terms of the Linux emulation
layer (ie, intended for both ISA - 32 & 64 bit), analogue of MD linux.h.
There must be a code here that cannot be placed into the corresponding by
common sense MI source and header files, i.e., code is machine independent,
but ISA dependent.
For the use_real_names knob, the code must be placed into the
linux_socket.[c|h], however linux_socket is ISA dependent.

MFC after:		2 weeks

sys/compat/linux/linux.c

@@ -59,6 +59,11 @@ __FBSDID("$FreeBSD$");
 
 CTASSERT(LINUX_IFNAMSIZ == IFNAMSIZ);
 
+static bool use_real_ifnames = false;
+SYSCTL_BOOL(_compat_linux, OID_AUTO, use_real_ifnames, CTLFLAG_RWTUN,
+    &use_real_ifnames, 0,
+    "Use FreeBSD interface names instead of generating ethN aliases");
+
 static int bsd_to_linux_sigtbl[LINUX_SIGTBLSZ] = {
 	LINUX_SIGHUP,	/* SIGHUP */
 	LINUX_SIGINT,	/* SIGINT */
@@ -723,3 +728,10 @@ bsd_to_linux_poll_events(short bev, short *lev)
 
 	*lev = bits;
 }
+
+bool
+linux_use_real_ifname(const struct ifnet *ifp)
+{
+
+	return (use_real_ifnames || !IFP_IS_ETH(ifp));
+}

sys/compat/linux/linux.h

@@ -284,6 +284,16 @@ struct l_statx {
 	ktrstruct("l_sigset_t", (s), l)
 #endif
 
+/*
+ * Criteria for interface name translation
+ */
+#define	IFP_IS_ETH(ifp)		((ifp)->if_type == IFT_ETHER)
+#define	IFP_IS_LOOP(ifp)	((ifp)->if_type == IFT_LOOP)
+
+struct ifnet;
+
+bool linux_use_real_ifname(const struct ifnet *);
+
 void linux_netlink_register(void);
 void linux_netlink_deregister(void);
 

sys/compat/linux/linux_util.c

@@ -50,10 +50,6 @@ __FBSDID("$FreeBSD$");
 #include <sys/systm.h>
 #include <sys/vnode.h>
 
-#include <net/if.h>
-#include <net/if_var.h>
-#include <net/if_types.h>
-
 #include <machine/stdarg.h>
 
 #include <compat/linux/linux_dtrace.h>
@@ -86,11 +82,6 @@ SYSCTL_STRING(_compat_linux, OID_AUTO, emul_path, CTLFLAG_RWTUN,
     linux_emul_path, sizeof(linux_emul_path),
     "Linux runtime environment path");
 
-static bool use_real_ifnames = false;
-SYSCTL_BOOL(_compat_linux, OID_AUTO, use_real_ifnames, CTLFLAG_RWTUN,
-    &use_real_ifnames, 0,
-    "Use FreeBSD interface names instead of generating ethN aliases");
-
 /*
  * Search an alternate path before passing pathname arguments on to
  * system calls. Useful for keeping a separate 'emulation tree'.
@@ -324,9 +315,3 @@ linux_device_unregister_handler(struct linux_device_handler *d)
 
 	return (EINVAL);
 }
-
-bool
-linux_use_real_ifname(const struct ifnet *ifp)
-{
-	return (use_real_ifnames || !IFP_IS_ETH(ifp));
-}

sys/compat/linux/linux_util.h

@@ -113,15 +113,6 @@ int	linux_vn_get_major_minor(const struct vnode *vn, int *major, int *minor);
 char	*linux_get_char_devices(void);
 void	linux_free_get_char_devices(char *string);
 
-/*
- * Criteria for interface name translation
- */
-#define	IFP_IS_ETH(ifp)		((ifp)->if_type == IFT_ETHER)
-#define	IFP_IS_LOOP(ifp)	((ifp)->if_type == IFT_LOOP)
-
-struct ifnet;
-bool	linux_use_real_ifname(const struct ifnet *ifp);
-
 #if defined(KTR)
 
 #define	KTR_LINUX				KTR_SUBSYS