ethtool: Name the 'no change' value for setting RSS hash key but not …

…indir table

We usually allocate special values of u32 fields starting from the top
down, so also change the value to 0xffffffff.  As these operations
haven't been included in a stable release yet, it's not too late to
change.

Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

include/uapi/linux/ethtool.h

@@ -850,7 +850,8 @@ struct ethtool_rxfh_indir {
  * struct ethtool_rxfh - command to get/set RX flow hash indir or/and hash key.
  * @cmd: Specific command number - %ETHTOOL_GRSSH or %ETHTOOL_SRSSH
  * @rss_context: RSS context identifier.
- * @indir_size: On entry, the array size of the user buffer, which may be zero.
+ * @indir_size: On entry, the array size of the user buffer, which may be zero,
+ *		or (for %ETHTOOL_SRSSH), %ETH_RXFH_INDIR_NO_CHANGE.
  *		On return from %ETHTOOL_GRSSH, the array size of the hardware
  *		indirection table.
  * @key_size:	On entry, the array size of the user buffer in bytes,
@@ -861,10 +862,10 @@ struct ethtool_rxfh_indir {
  *		of size @indir_size followed by hash key of size @key_size.
  *
  * For %ETHTOOL_GRSSH, a @indir_size and key_size of zero means that only the
- * size should be returned.  For %ETHTOOL_SRSSH, a @indir_size of 0xDEADBEEF
- * means that indir table setting is not requested and a @indir_size of zero
- * means the indir table should be reset to default values.  This last feature
- * is not supported by the original implementations.
+ * size should be returned.  For %ETHTOOL_SRSSH, an @indir_size of
+ * %ETH_RXFH_INDIR_NO_CHANGE means that indir table setting is not requested
+ * and a @indir_size of zero means the indir table should be reset to default
+ * values.
  */
 struct ethtool_rxfh {
 	__u32   cmd;
@@ -874,6 +875,7 @@ struct ethtool_rxfh {
 	__u32	rsvd[2];
 	__u32   rss_config[0];
 };
+#define ETH_RXFH_INDIR_NO_CHANGE	0xffffffff
 
 /**
  * struct ethtool_rx_ntuple_flow_spec - specification for RX flow filter

net/core/ethtool.c

@@ -803,12 +803,13 @@ static noinline_for_stack int ethtool_set_rxfh(struct net_device *dev,
 
 	/* If either indir or hash key is valid, proceed further.
 	 */
-	if ((user_indir_size && ((user_indir_size != 0xDEADBEEF) &&
-				 user_indir_size != dev_indir_size)) ||
+	if ((user_indir_size &&
+	     user_indir_size != ETH_RXFH_INDIR_NO_CHANGE &&
+	     user_indir_size != dev_indir_size) ||
 	    (user_key_size && (user_key_size != dev_key_size)))
 		return -EINVAL;
 
-	if (user_indir_size != 0xDEADBEEF)
+	if (user_indir_size != ETH_RXFH_INDIR_NO_CHANGE)
 		indir_bytes = dev_indir_size * sizeof(indir[0]);
 
 	rss_config = kzalloc(indir_bytes + user_key_size, GFP_USER);
@@ -821,9 +822,10 @@ static noinline_for_stack int ethtool_set_rxfh(struct net_device *dev,
 		goto out;
 
 	/* user_indir_size == 0 means reset the indir table to default.
-	 * user_indir_size == 0xDEADBEEF means indir setting is not requested.
+	 * user_indir_size == ETH_RXFH_INDIR_NO_CHANGE means leave it unchanged.
 	 */
-	if (user_indir_size && user_indir_size != 0xDEADBEEF) {
+	if (user_indir_size &&
+	    user_indir_size != ETH_RXFH_INDIR_NO_CHANGE) {
 		indir = (u32 *)rss_config;
 		ret = ethtool_copy_validate_indir(indir,
 						  useraddr + rss_cfg_offset,