datapath: Fix builds on older kernels.

On older kernels, for example 3.19, the function rt6_get_cookie() is
not available and used with ipv6 config enabled;  it was introduced in
4.2.  Put back the replacement function if it does not exist.
Add a 3.19 version to travis.

CC: Yifeng Sun <[email protected]>
Fixes: bf61b8b ("datapath: Add support for kernel 4.16.x & 4.17.x.")
Signed-off-by: Darrell Ball <[email protected]>
Signed-off-by: Ben Pfaff <[email protected]>
Tested-by: Yifeng Sun <[email protected]>
Reviewed-by: Yifeng Sun <[email protected]>

.travis.yml

@@ -41,6 +41,7 @@ env:
   - KERNEL=4.14.63
   - KERNEL=4.9.120
   - KERNEL=4.4.148
+  - KERNEL=3.19.8
   - KERNEL=3.16.57
   - TESTSUITE=1 LIBS=-ljemalloc
 

acinclude.m4

@@ -459,6 +459,9 @@ AC_DEFUN([OVS_CHECK_LINUX_COMPAT], [
   OVS_GREP_IFELSE([$KSRC/arch/x86/include/asm/checksum_32.h], [src_err,],
                   [OVS_DEFINE([HAVE_CSUM_COPY_DBG])])
 
+  OVS_GREP_IFELSE([$KSRC/include/net/ip6_fib.h], [rt6_get_cookie],
+                  [OVS_DEFINE([HAVE_RT6_GET_COOKIE])])
+
   OVS_GREP_IFELSE([$KSRC/include/net/addrconf.h], [ipv6_dst_lookup.*net],
                   [OVS_DEFINE([HAVE_IPV6_DST_LOOKUP_NET])])
   OVS_GREP_IFELSE([$KSRC/include/net/addrconf.h], [ipv6_stub])
@@ -803,6 +806,8 @@ AC_DEFUN([OVS_CHECK_LINUX_COMPAT], [
                   [OVS_DEFINE(HAVE_NF_CONNTRACK_HELPER_PUT)])
   OVS_GREP_IFELSE([$KSRC/include/linux/skbuff.h],[[[[:space:]]]SKB_GSO_UDP[[[:space:]]]],
                   [OVS_DEFINE([HAVE_SKB_GSO_UDP])])
+  OVS_GREP_IFELSE([$KSRC/include/net/dst.h],[DST_NOCACHE],
+                  [OVS_DEFINE([HAVE_DST_NOCACHE])])
   OVS_FIND_FIELD_IFELSE([$KSRC/include/net/rtnetlink.h], [rtnl_link_ops],
                         [extack],
                   [OVS_DEFINE([HAVE_EXT_ACK_IN_RTNL_LINKOPS])])

datapath/linux/Modules.mk

@@ -82,6 +82,7 @@ openvswitch_headers += \
 	linux/compat/include/net/inetpeer.h \
 	linux/compat/include/net/ip.h \
 	linux/compat/include/net/ip_tunnels.h \
+        linux/compat/include/net/ip6_fib.h \
 	linux/compat/include/net/ip6_route.h \
 	linux/compat/include/net/ip6_tunnel.h \
 	linux/compat/include/net/ipv6.h \

datapath/linux/compat/include/net/ip6_fib.h

@@ -0,0 +1,43 @@
+/*
+ *      Linux INET6 implementation
+ *
+ *      Authors:
+ *      Pedro Roque             <[email protected]>
+ *
+ *      This program is free software; you can redistribute it and/or
+ *      modify it under the terms of the GNU General Public License
+ *      as published by the Free Software Foundation; either version
+ *      2 of the License, or (at your option) any later version.
+ */
+
+#ifndef _IP6_FIB_WRAPPER_H
+#define _IP6_FIB_WRAPPER_H
+
+#include_next <net/ip6_fib.h>
+
+#ifndef HAVE_RT6_GET_COOKIE
+
+#ifndef RTF_PCPU
+#define RTF_PCPU        0x40000000
+#endif
+
+#ifndef RTF_LOCAL
+#define RTF_LOCAL       0x80000000
+#endif
+
+#define rt6_get_cookie rpl_rt6_get_cookie
+static inline u32 rt6_get_cookie(const struct rt6_info *rt)
+{
+       if (rt->rt6i_flags & RTF_PCPU ||
+#ifdef HAVE_DST_NOCACHE
+           (unlikely(rt->dst.flags & DST_NOCACHE) && rt->dst.from))
+#else
+           (unlikely(!list_empty(&rt->rt6i_uncached)) && rt->dst.from))
+#endif
+               rt = (struct rt6_info *)(rt->dst.from);
+
+       return rt->rt6i_node ? rt->rt6i_node->fn_sernum : 0;
+}
+#endif
+
+#endif