[RFC PATCH net-next 1/3] net: ethtool: add symmetric Toeplitz RSS hash function

[Ahmed Zaki <ahmed.zaki@intel.com>]

Symmetric RSS hash functions are beneficial in applications that monitor
both Tx and Rx packets of the same flow (IDS, software firewalls, ..etc).
Getting all traffic of the same flow on the same RX queue results in
higher CPU cache efficiency.

Allow ethtool to support symmetric Toeplitz algorithm. A user can set the
RSS function of the netdevice via:
    # ethtool -X eth0 hfunc symmetric_toeplitz

Signed-off-by: Ahmed Zaki <ahmed.zaki@intel.com>
---
 include/linux/ethtool.h | 4 +++-
 net/ethtool/common.c    | 1 +
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/include/linux/ethtool.h b/include/linux/ethtool.h
index 62b61527bcc4..9a8e1fb7170d 100644
--- a/include/linux/ethtool.h
+++ b/include/linux/ethtool.h
@@ -60,10 +60,11 @@ enum {
 	ETH_RSS_HASH_TOP_BIT, /* Configurable RSS hash function - Toeplitz */
 	ETH_RSS_HASH_XOR_BIT, /* Configurable RSS hash function - Xor */
 	ETH_RSS_HASH_CRC32_BIT, /* Configurable RSS hash function - Crc32 */
+	ETH_RSS_HASH_SYM_TOP_BIT, /* Configurable RSS hash function - Symmetric Toeplitz */
 
 	/*
 	 * Add your fresh new hash function bits above and remember to update
-	 * rss_hash_func_strings[] in ethtool.c
+	 * rss_hash_func_strings[] in ethtool/common.c
 	 */
 	ETH_RSS_HASH_FUNCS_COUNT
 };
@@ -108,6 +109,7 @@ enum ethtool_supported_ring_param {
 #define __ETH_RSS_HASH(name)	__ETH_RSS_HASH_BIT(ETH_RSS_HASH_##name##_BIT)
 
 #define ETH_RSS_HASH_TOP	__ETH_RSS_HASH(TOP)
+#define ETH_RSS_HASH_SYM_TOP	__ETH_RSS_HASH(SYM_TOP)
 #define ETH_RSS_HASH_XOR	__ETH_RSS_HASH(XOR)
 #define ETH_RSS_HASH_CRC32	__ETH_RSS_HASH(CRC32)
 
diff --git a/net/ethtool/common.c b/net/ethtool/common.c
index f5598c5f50de..a0e0c6b2980e 100644
--- a/net/ethtool/common.c
+++ b/net/ethtool/common.c
@@ -81,6 +81,7 @@ rss_hash_func_strings[ETH_RSS_HASH_FUNCS_COUNT][ETH_GSTRING_LEN] = {
 	[ETH_RSS_HASH_TOP_BIT] =	"toeplitz",
 	[ETH_RSS_HASH_XOR_BIT] =	"xor",
 	[ETH_RSS_HASH_CRC32_BIT] =	"crc32",
+	[ETH_RSS_HASH_SYM_TOP_BIT] =	"symmetric_toeplitz",
 };
 
 const char
-- 
2.39.2