[ovs-dev] [PATCH V2 2/3] compat: Fix build issue on RHEL 7.7

[Greg Rose]

RHEL 7.2 introduced a KABI fixup in struct sk_buff for the name
change of  l4_rxhash to l4_hash.  Then patch
9ba57fc7cccc ("datapath: Add hash info to upcall") introduced a
compile error by using l4_hash and not fixing up the HAVE_L4_RXHASH
configuration flag.

Remove all references to HAVE_L4_RXHASH and always use l4_hash to
resolve the issue.  This will break compilation on RHEL 7.0 and
RHEL 7.1 but dropping support for these older kernels shouldn't be
a problem.

Fixes: 9ba57fc7cccc ("datapath: Add hash info to upcall")
Signed-off-by: Greg Rose <gvrose8192 at gmail.com>

---
V2 - Just removes l4_rxhash and ends support for RHEL 7.x < 7.2
---
 acinclude.m4                                 |  2 --
 datapath/datapath.c                          |  4 ----
 datapath/linux/compat/include/linux/skbuff.h | 10 ++--------
 3 files changed, 2 insertions(+), 14 deletions(-)

diff --git a/acinclude.m4 b/acinclude.m4
index 9c2236f9e..ddf4b71e1 100644
--- a/acinclude.m4
+++ b/acinclude.m4
@@ -877,8 +877,6 @@ AC_DEFUN([OVS_CHECK_LINUX_COMPAT], [
   OVS_GREP_IFELSE([$KSRC/include/linux/skbuff.h], [skb_clear_hash])
   OVS_GREP_IFELSE([$KSRC/include/linux/skbuff.h], [int.skb_zerocopy(],
                   [OVS_DEFINE([HAVE_SKB_ZEROCOPY])])
-  OVS_GREP_IFELSE([$KSRC/include/linux/skbuff.h], [u8.*l4_rxhash],
-                  [OVS_DEFINE([HAVE_L4_RXHASH])])
   OVS_GREP_IFELSE([$KSRC/include/linux/skbuff.h], [skb_ensure_writable])
   OVS_GREP_IFELSE([$KSRC/include/linux/skbuff.h], [skb_vlan_pop])
   OVS_GREP_IFELSE([$KSRC/include/linux/skbuff.h], [__skb_vlan_pop])
diff --git a/datapath/datapath.c b/datapath/datapath.c
index 52a59f135..8e9b9a706 100644
--- a/datapath/datapath.c
+++ b/datapath/datapath.c
@@ -529,11 +529,7 @@ static int queue_userspace_packet(struct datapath *dp, struct sk_buff *skb,
 		hash |= OVS_PACKET_HASH_SW_BIT;
 #endif
 
-#ifdef HAVE_L4_RXHASH
-	if (skb->l4_rxhash)
-#else
 	if (skb->l4_hash)
-#endif
 		hash |= OVS_PACKET_HASH_L4_BIT;
 
 	if (nla_put(user_skb, OVS_PACKET_ATTR_HASH, sizeof (u64), &hash)) {
diff --git a/datapath/linux/compat/include/linux/skbuff.h b/datapath/linux/compat/include/linux/skbuff.h
index bc73255d5..d3bc6c715 100644
--- a/datapath/linux/compat/include/linux/skbuff.h
+++ b/datapath/linux/compat/include/linux/skbuff.h
@@ -278,9 +278,7 @@ static inline void skb_clear_hash(struct sk_buff *skb)
 #ifdef HAVE_RXHASH
 	skb->rxhash = 0;
 #endif
-#if defined(HAVE_L4_RXHASH)
-	skb->l4_rxhash = 0;
-#endif
+ 	skb->l4_hash = 0;
 }
 #endif
 
@@ -371,7 +369,7 @@ static inline void skb_pop_mac_header(struct sk_buff *skb)
 #ifndef HAVE_SKB_CLEAR_HASH_IF_NOT_L4
 static inline void skb_clear_hash_if_not_l4(struct sk_buff *skb)
 {
-	if (!skb->l4_rxhash)
+	if (!skb->l4_hash)
 		skb_clear_hash(skb);
 }
 #endif
@@ -465,11 +463,7 @@ __skb_set_hash(struct sk_buff *skb, __u32 hash, bool is_sw, bool is_l4)
 #else
 	skb->hash = hash;
 #endif
-#if defined(HAVE_L4_RXHASH)
-	skb->l4_rxhash = is_l4;
-#else
 	skb->l4_hash = is_l4;
-#endif
 #ifdef HAVE_SW_HASH
 	skb->sw_hash = is_sw;
 #endif
-- 
2.17.1