[PATCH 3.16 64/87] be2net: Fix number of Rx queues used for flow hashing

[Ben Hutchings]

3.16.75-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Ivan Vecera <ivecera@xxxxxxxxxx>

commit 718f4a2537089ea41903bf357071306163bc7c04 upstream.

Number of Rx queues used for flow hashing returned by the driver is
incorrect and this bug prevents user to use the last Rx queue in
indirection table.

Let's say we have a NIC with 6 combined queues:

[root@sm-03 ~]# ethtool -l enp4s0f0
Channel parameters for enp4s0f0:
Pre-set maximums:
RX:             5
TX:             5
Other:          0
Combined:       6
Current hardware settings:
RX:             0
TX:             0
Other:          0
Combined:       6

Default indirection table maps all (6) queues equally but the driver
reports only 5 rings available.

[root@sm-03 ~]# ethtool -x enp4s0f0
RX flow hash indirection table for enp4s0f0 with 5 RX ring(s):
    0:      0     1     2     3     4     5     0     1
    8:      2     3     4     5     0     1     2     3
   16:      4     5     0     1     2     3     4     5
   24:      0     1     2     3     4     5     0     1
...

Now change indirection table somehow:

[root@sm-03 ~]# ethtool -X enp4s0f0 weight 1 1
[root@sm-03 ~]# ethtool -x enp4s0f0
RX flow hash indirection table for enp4s0f0 with 6 RX ring(s):
    0:      0     0     0     0     0     0     0     0
...
   64:      1     1     1     1     1     1     1     1
...

Now it is not possible to change mapping back to equal (default) state:

[root@sm-03 ~]# ethtool -X enp4s0f0 equal 6
Cannot set RX flow hash configuration: Invalid argument

Fixes: 594ad54a2c3b ("be2net: Add support for setting and getting rx flow hash options")
Reported-by: Tianhao <tizhao@xxxxxxxxxx>
Signed-off-by: Ivan Vecera <ivecera@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 drivers/net/ethernet/emulex/benet/be_ethtool.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/net/ethernet/emulex/benet/be_ethtool.c
+++ b/drivers/net/ethernet/emulex/benet/be_ethtool.c
@@ -962,7 +962,7 @@ static int be_get_rxnfc(struct net_devic
 		cmd->data = be_get_rss_hash_opts(adapter, cmd->flow_type);
 		break;
 	case ETHTOOL_GRXRINGS:
-		cmd->data = adapter->num_rx_qs - 1;
+		cmd->data = adapter->num_rx_qs;
 		break;
 	default:
 		return -EINVAL;