Thread (16 messages) 16 messages, 3 authors, 2015-05-31

Re: [PATCH v4 net-next 09/11] net: Add IPv6 flow label to flow_keys

From: Eric Dumazet <hidden>
Date: 2015-05-29 00:36:39

On Thu, 2015-05-28 at 11:19 -0700, Tom Herbert wrote:
quoted hunk ↗ jump to hunk
In flow_dissector set the flow label in flow_keys for IPv6. This also
removes the shortcircuiting of flow dissection when a non-zero label
is present, the flow label can be considered to provide additional
entropy for a hash.

Signed-off-by: Tom Herbert <redacted>
---
 include/net/flow_dissector.h |  4 +++-
 net/core/flow_dissector.c    | 31 +++++++++++--------------------
 2 files changed, 14 insertions(+), 21 deletions(-)
diff --git a/include/net/flow_dissector.h b/include/net/flow_dissector.h
index 08480fb..14d8483 100644
--- a/include/net/flow_dissector.h
+++ b/include/net/flow_dissector.h
@@ -28,7 +28,8 @@ struct flow_dissector_key_basic {
 };
 
 struct flow_dissector_key_tags {
-	u32	vlan_id:12;
+	u32	vlan_id:12,
+		flow_label:20;
 };
 
 /**
@@ -111,6 +112,7 @@ enum flow_dissector_key_id {
 	FLOW_DISSECTOR_KEY_ETH_ADDRS, /* struct flow_dissector_key_eth_addrs */
 	FLOW_DISSECTOR_KEY_TIPC_ADDRS, /* struct flow_dissector_key_tipc_addrs */
 	FLOW_DISSECTOR_KEY_VLANID, /* struct flow_dissector_key_flow_tags */
+	FLOW_DISSECTOR_KEY_FLOW_LABEL, /* struct flow_dissector_key_flow_tags */
 
 	FLOW_DISSECTOR_KEY_MAX,
 };
diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c
index 5c66cb2..ba089d9 100644
--- a/net/core/flow_dissector.c
+++ b/net/core/flow_dissector.c
@@ -190,7 +190,7 @@ ip:
 	case htons(ETH_P_IPV6): {
 		const struct ipv6hdr *iph;
 		struct ipv6hdr _iph;
-		__be32 flow_label;
+		u32 flow_label;
You change flow_label from __be32 to u32.
quoted hunk ↗ jump to hunk
 
 ipv6:
 		iph = __skb_header_pointer(skb, nhoff, sizeof(_iph), data, hlen, &_iph);
@@ -210,30 +210,17 @@ ipv6:
 
 			memcpy(key_ipv6_addrs, &iph->saddr, sizeof(*key_ipv6_addrs));
 			key_control->addr_type = FLOW_DISSECTOR_KEY_IPV6_ADDRS;
-			goto flow_label;
 		}
-		break;
-flow_label:
+
 		flow_label = ip6_flowlabel(iph);
But ip6_flowlabel() returns a __be32. This should not please sparse.

 		if (flow_label) {
-			/* Awesome, IPv6 packet has a flow label so we can
-			 * use that to represent the ports without any
-			 * further dissection.
-			 */
-
-			key_basic->n_proto = proto;
-			key_basic->ip_proto = ip_proto;
-			key_control->thoff = (u16)nhoff;
-
 			if (skb_flow_dissector_uses_key(flow_dissector,
-							FLOW_DISSECTOR_KEY_PORTS)) {
-				key_ports = skb_flow_dissector_target(flow_dissector,
-								      FLOW_DISSECTOR_KEY_PORTS,
-								      target_container);
-				key_ports->ports = flow_label;
+				FLOW_DISSECTOR_KEY_FLOW_LABEL)) {
+				key_tags = skb_flow_dissector_target(flow_dissector,
+								     FLOW_DISSECTOR_KEY_FLOW_LABEL,
+								     target_container);
+				key_tags->flow_label = ntohl(flow_label);
Then you call ntohl() on u32 variable. This should also complain.

Have you run sparse ?

make C=2 CF=-D__CHECK_ENDIAN__ net/core/flow_dissector.o

Thanks.
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