datapath: compat: keep skb mark across tunnel devices.

Older kernel skb_scrub_packet() has bug which resets skb mark for
all packet. It is fixed during 3.18 release where it is reset
only for packets crossing namespace. So OVS is forced to use
compat skb_scrub_packet() on older kernel.
This is related to upstream bug fix commit ca7c7b9059e3
("skbuff: Do not scrub skb mark within the same name space").

VMware-BZ: #1710701
Signed-off-by: Pravin B Shelar <[email protected]>
Acked-by: Joe Stringer <[email protected]>

acinclude.m4

@@ -551,8 +551,6 @@ AC_DEFUN([OVS_CHECK_LINUX_COMPAT], [
   OVS_GREP_IFELSE([$KSRC/include/linux/skbuff.h], [inner_protocol_type])
   OVS_GREP_IFELSE([$KSRC/include/linux/skbuff.h], [skb_inner_transport_offset])
   OVS_GREP_IFELSE([$KSRC/include/linux/skbuff.h], [kfree_skb_list])
-  OVS_GREP_IFELSE([$KSRC/include/linux/skbuff.h], [skb_scrub_packet.*xnet],
-		  [OVS_DEFINE([HAVE_SKB_SCRUB_PACKET_XNET])])
   OVS_GREP_IFELSE([$KSRC/include/linux/skbuff.h], [rxhash])
   OVS_GREP_IFELSE([$KSRC/include/linux/skbuff.h], [u16.*rxhash],
                   [OVS_DEFINE([HAVE_U16_RXHASH])])

datapath/linux/compat/include/linux/skbuff.h

@@ -310,7 +310,7 @@ static inline unsigned char *skb_pull_rcsum(struct sk_buff *skb, unsigned int le
 
 #endif
 
-#ifndef HAVE_SKB_SCRUB_PACKET_XNET
+#if LINUX_VERSION_CODE < KERNEL_VERSION(4,1,0)
 #define skb_scrub_packet rpl_skb_scrub_packet
 void rpl_skb_scrub_packet(struct sk_buff *skb, bool xnet);
 #endif

datapath/linux/compat/skbuff-openvswitch.c

@@ -278,7 +278,7 @@ void rpl_kfree_skb_list(struct sk_buff *segs)
 EXPORT_SYMBOL(rpl_kfree_skb_list);
 #endif
 
-#ifndef HAVE_SKB_SCRUB_PACKET_XNET
+#if LINUX_VERSION_CODE < KERNEL_VERSION(4,1,0)
 
 #define nf_reset_trace rpl_nf_reset_trace
 static void nf_reset_trace(struct sk_buff *skb)