[ovs-dev] [RFC patch v1] datapath: Fix builds on older kernels.

[Darrell Ball]

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.

CC: Yifeng Sun <pkusunyifeng at gmail.com>
Fixes: bf61b8b1c1db ("datapath: Add support for kernel 4.16.x & 4.17.x.")
Signed-off-by: Darrell Ball <dlu998 at gmail.com>
---
 acinclude.m4                                |  5 ++++
 datapath/linux/Modules.mk                   |  1 +
 datapath/linux/compat/include/net/ip6_fib.h | 43 +++++++++++++++++++++++++++++
 3 files changed, 49 insertions(+)
 create mode 100644 datapath/linux/compat/include/net/ip6_fib.h

diff --git a/acinclude.m4 b/acinclude.m4
index ab141bd..0690bae 100644
--- a/acinclude.m4
+++ b/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])])
diff --git a/datapath/linux/Modules.mk b/datapath/linux/Modules.mk
index b06ca15..e31d784 100644
--- a/datapath/linux/Modules.mk
+++ b/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 \
diff --git a/datapath/linux/compat/include/net/ip6_fib.h b/datapath/linux/compat/include/net/ip6_fib.h
new file mode 100644
index 0000000..0cc4358
--- /dev/null
+++ b/datapath/linux/compat/include/net/ip6_fib.h
@@ -0,0 +1,43 @@
+/*
+ *      Linux INET6 implementation
+ *
+ *      Authors:
+ *      Pedro Roque             <roque at di.fc.ul.pt>
+ *
+ *      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
-- 
1.9.1