diff mbox series

net: let flow have same hash in two directions

Message ID 20210728105418.7379-1-zhangkaiheb@126.com
State New
Headers show
Series net: let flow have same hash in two directions | expand

Commit Message

zhang kai July 28, 2021, 10:54 a.m. UTC 
using same source and destination ip/port for flow hash calculation
within the two directions.

Signed-off-by: zhang kai <zhangkaiheb@126.com>
---
 net/core/flow_dissector.c | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

Comments

Jakub Kicinski July 30, 2021, 10:59 a.m. UTC | #1 
On Wed, 28 Jul 2021 18:54:18 +0800 zhang kai wrote:
> using same source and destination ip/port for flow hash calculation

> within the two directions.


Did you observe the hash being different, or just found this by code
inspection? AFAICT the existing code was fine, and probably slightly
faster.
diff mbox series

Patch

diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c
index 3ed7c98a9..dfc18f212 100644
--- a/net/core/flow_dissector.c
+++ b/net/core/flow_dissector.c
@@ -1504,7 +1504,7 @@  __be32 flow_get_u32_dst(const struct flow_keys *flow)
 }
 EXPORT_SYMBOL(flow_get_u32_dst);
 
-/* Sort the source and destination IP (and the ports if the IP are the same),
+/* Sort the source and destination IP and the ports,
  * to have consistent hash within the two directions
  */
 static inline void __flow_hash_consistentify(struct flow_keys *keys)
@@ -1515,11 +1515,11 @@  static inline void __flow_hash_consistentify(struct flow_keys *keys)
 	case FLOW_DISSECTOR_KEY_IPV4_ADDRS:
 		addr_diff = (__force u32)keys->addrs.v4addrs.dst -
 			    (__force u32)keys->addrs.v4addrs.src;
-		if ((addr_diff < 0) ||
-		    (addr_diff == 0 &&
-		     ((__force u16)keys->ports.dst <
-		      (__force u16)keys->ports.src))) {
+		if (addr_diff < 0)
 			swap(keys->addrs.v4addrs.src, keys->addrs.v4addrs.dst);
+
+		if ((__force u16)keys->ports.dst <
+		    (__force u16)keys->ports.src) {
 			swap(keys->ports.src, keys->ports.dst);
 		}
 		break;
@@ -1527,13 +1527,13 @@  static inline void __flow_hash_consistentify(struct flow_keys *keys)
 		addr_diff = memcmp(&keys->addrs.v6addrs.dst,
 				   &keys->addrs.v6addrs.src,
 				   sizeof(keys->addrs.v6addrs.dst));
-		if ((addr_diff < 0) ||
-		    (addr_diff == 0 &&
-		     ((__force u16)keys->ports.dst <
-		      (__force u16)keys->ports.src))) {
+		if (addr_diff < 0) {
 			for (i = 0; i < 4; i++)
 				swap(keys->addrs.v6addrs.src.s6_addr32[i],
 				     keys->addrs.v6addrs.dst.s6_addr32[i]);
+		}
+		if ((__force u16)keys->ports.dst <
+		    (__force u16)keys->ports.src) {
 			swap(keys->ports.src, keys->ports.dst);
 		}
 		break;