ethtool: add CRC32 as an RSS hash function

CRC32 engines are usually easily available in hardware and generate
OK spread for RSS hash.  Add CRC32 RSS hash function to ethtool API.
Signed-off-by: NJakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

include/linux/ethtool.h

@@ -60,6 +60,7 @@ enum ethtool_phys_id_state {
 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 */
 
 	/*
 	 * Add your fresh new hash function bits above and remember to update
@@ -73,6 +74,7 @@ enum {
 
 #define ETH_RSS_HASH_TOP	__ETH_RSS_HASH(TOP)
 #define ETH_RSS_HASH_XOR	__ETH_RSS_HASH(XOR)
+#define ETH_RSS_HASH_CRC32	__ETH_RSS_HASH(CRC32)
 
 #define ETH_RSS_HASH_UNKNOWN	0
 #define ETH_RSS_HASH_NO_CHANGE	0

net/core/ethtool.c

@@ -109,6 +109,7 @@ static const char
 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",
 };
 
 static const char