ethtool: Disallow ETHTOOL_SRSSH with both indir table and hash key unchanged

This would be a no-op, so there is no reason to request it.

This also allows conversion of the current implementations of
ethtool_ops::{get,set}_rxfh_indir to ethtool_ops::{get,set}_rxfh
with no change other than their parameters.

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

2 files changed, 6 insertions, 3 deletions

diff --git a/include/linux/ethtool.h b/include/linux/ethtool.h
index 886e127d51a6..de687a97c6e7 100644
--- a/include/linux/ethtool.h
+++ b/include/linux/ethtool.h
@@ -168,8 +168,8 @@ static inline u32 ethtool_rxfh_indir_default(u32 index, u32 n_rx_rings)
  * @set_rxfh_indir: Set the contents of the RX flow hash indirection table.
  *      Will not be called if @get_rxfh_indir_size returns zero.
  * @set_rxfh: Set the contents of the RX flow hash indirection table and/or
- *      hash key.  Either or both arguments may be %NULL if that attribute
- *      is not to be changed.
+ *      hash key.  In case only the indirection table or hash key is to be
+ *      changed, the other argument will be %NULL.
  *      Will only be called if one or both of @get_rxfh_indir_size and
  *      @get_rxfh_key_size are implemented and return non-zero.
  *      Returns a negative error code or zero.
diff --git a/net/core/ethtool.c b/net/core/ethtool.c
index 7156fe5ca876..b8857348bdf3 100644
--- a/net/core/ethtool.c
+++ b/net/core/ethtool.c
@@ -802,11 +802,14 @@ static noinline_for_stack int ethtool_set_rxfh(struct net_device *dev,
                 return -EFAULT;
 
         /* If either indir or hash key is valid, proceed further.
+         * It is not valid to request that both be unchanged.
          */
         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)))
+            (user_key_size && (user_key_size != dev_key_size)) ||
+            (user_indir_size == ETH_RXFH_INDIR_NO_CHANGE &&
+             user_key_size == 0))
                 return -EINVAL;
 
         if (user_indir_size != ETH_RXFH_INDIR_NO_CHANGE)