ice: change q_index variable type to s16 to store -1 value

Fix Flow Director not allowing to re-map traffic to 0th queue when action
is configured to drop (and vice versa).

The current implementation of ethtool callback in the ice driver forbids
change Flow Director action from 0 to -1 and from -1 to 0 with an error,
e.g:

 # ethtool -U eth2 flow-type tcp4 src-ip 1.1.1.1 loc 1 action 0
 # ethtool -U eth2 flow-type tcp4 src-ip 1.1.1.1 loc 1 action -1
 rmgr: Cannot insert RX class rule: Invalid argument

We set the value of `u16 q_index = 0` at the beginning of the function
ice_set_fdir_input_set(). In case of "drop traffic" action (which is
equal to -1 in ethtool) we store the 0 value. Later, when want to change
traffic rule to redirect to queue with index 0 it returns an error
caused by duplicate found.

Fix this behaviour by change of the type of field `q_index` from u16 to s16
in `struct ice_fdir_fltr`. This allows to store -1 in the field in case
of "drop traffic" action. What is more, change the variable type in the
function ice_set_fdir_input_set() and assign at the beginning the new
`#define ICE_FDIR_NO_QUEUE_IDX` which is -1. Later, if the action is set
to another value (point specific queue index) the variable value is
overwritten in the function.

Fixes: cac2a27 ("ice: Support IPv4 Flow Director filters")
Reviewed-by: Przemek Kitszel <[email protected]>
Signed-off-by: Mateusz Polchlopek <[email protected]>
Reviewed-by: Simon Horman <[email protected]>
Tested-by: Pucha Himasekhar Reddy <[email protected]> (A Contingent worker at Intel)
Signed-off-by: Tony Nguyen <[email protected]>

Author: halfboy93

drivers/net/ethernet/intel/ice/ice_ethtool_fdir.c

@@ -1830,11 +1830,12 @@ static int
 ice_set_fdir_input_set(struct ice_vsi *vsi, struct ethtool_rx_flow_spec *fsp,
 		       struct ice_fdir_fltr *input)
 {
-	u16 dest_vsi, q_index = 0;
+	s16 q_index = ICE_FDIR_NO_QUEUE_IDX;
 	u16 orig_q_index = 0;
 	struct ice_pf *pf;
 	struct ice_hw *hw;
 	int flow_type;
+	u16 dest_vsi;
 	u8 dest_ctl;
 
 	if (!vsi || !fsp || !input)

drivers/net/ethernet/intel/ice/ice_fdir.h

@@ -53,6 +53,8 @@
  */
 #define ICE_FDIR_IPV4_PKT_FLAG_MF		0x20
 
+#define ICE_FDIR_NO_QUEUE_IDX			-1
+
 enum ice_fltr_prgm_desc_dest {
 	ICE_FLTR_PRGM_DESC_DEST_DROP_PKT,
 	ICE_FLTR_PRGM_DESC_DEST_DIRECT_PKT_QINDEX,
@@ -186,7 +188,7 @@ struct ice_fdir_fltr {
 	u16 flex_fltr;
 
 	/* filter control */
-	u16 q_index;
+	s16 q_index;
 	u16 orig_q_index;
 	u16 dest_vsi;
 	u8 dest_ctl;