[ovs-dev] [PATCH] [rfc] datapath: Clear rxhash when using an action that may affect it

[Simon Horman]

Signed-off-by: Simon Horman <horms at verge.net.au>

---

Several moons ago Jesse Gross mentioned that the rxhash ought
to be cleared when the datapath makes a modification that could
affect it. This patch is a first pass at making that change.

Compile tested only.
---
 acinclude.m4       |    2 ++
 datapath/actions.c |   11 +++++++++++
 2 files changed, 13 insertions(+), 0 deletions(-)

diff --git a/acinclude.m4 b/acinclude.m4
index 6fc1c7a..4999d05 100644
--- a/acinclude.m4
+++ b/acinclude.m4
@@ -186,6 +186,8 @@ AC_DEFUN([OVS_CHECK_LINUX26_COMPAT], [
                   [OVS_DEFINE([HAVE_SKBUFF_HEADER_HELPERS])])
   OVS_GREP_IFELSE([$KSRC26/include/linux/skbuff.h], [skb_warn_if_lro],
                   [OVS_DEFINE([HAVE_SKB_WARN_LRO])])
+  OVS_GREP_IFELSE([$KSRC26/include/linux/skbuff.h], [rxhash],
+                  [OVS_DEFINE([HAVE_RXHASH])])
 
   OVS_GREP_IFELSE([$KSRC26/include/linux/string.h], [kmemdup], [],
                   [OVS_GREP_IFELSE([$KSRC26/include/linux/slab.h], [kmemdup])])
diff --git a/datapath/actions.c b/datapath/actions.c
index 3223c65..b8495aa 100644
--- a/datapath/actions.c
+++ b/datapath/actions.c
@@ -26,6 +26,13 @@
 #include "openvswitch/datapath-protocol.h"
 #include "vport.h"
 
+static void skb_clear_rxhash(struct sk_buff *skb)
+{
+#ifdef HAVE_RXHASH
+	skb->rxhash = 0;
+#endif
+}
+
 static int do_execute_actions(struct datapath *, struct sk_buff *,
 			      const struct sw_flow_key *,
 			      const struct nlattr *actions, u32 actions_len);
@@ -250,6 +257,8 @@ static struct sk_buff *set_nw_addr(struct sk_buff *skb,
 		inet_proto_csum_replace4(check, skb, *nwaddr, new_nwaddr, 1);
 	csum_replace4(&nh->check, *nwaddr, new_nwaddr);
 
+	skb_clear_rxhash(skb);
+
 	*nwaddr = new_nwaddr;
 
 	return skb;
@@ -309,6 +318,7 @@ static struct sk_buff *set_tp_port(struct sk_buff *skb,
 	port = nla_type(a) == ODP_ACTION_ATTR_SET_TP_SRC ? &th->source : &th->dest;
 	inet_proto_csum_replace2(check, skb, *port, nla_get_be16(a), 0);
 	*port = nla_get_be16(a);
+	skb_clear_rxhash(skb);
 
 	return skb;
 }
@@ -413,6 +423,7 @@ static int do_execute_actions(struct datapath *dp, struct sk_buff *skb,
 
 		case ODP_ACTION_ATTR_SET_TUNNEL:
 			OVS_CB(skb)->tun_id = nla_get_be64(a);
+			skb_clear_rxhash(skb);
 			break;
 
 		case ODP_ACTION_ATTR_SET_DL_TCI:
-- 
1.7.2.3