[PATCH net] ethtool: fix the check logic of at least one channel for RX/TX

[Simon Horman]

From: Yinjun Zhang <yinjun.zh...@corigine.com>

The command "ethtool -L <intf> combined 0" may clean the RX/TX channel
count and skip the error path, since the attrs
tb[ETHTOOL_A_CHANNELS_RX_COUNT] and tb[ETHTOOL_A_CHANNELS_TX_COUNT]
are NULL in this case when recent ethtool is used.

Tested using ethtool v5.10.

Fixes: 7be92514b99c ("ethtool: check if there is at least one channel for TX/RX 
in the core")
Signed-off-by: Yinjun Zhang <yinjun.zh...@corigine.com>
Signed-off-by: Simon Horman <simon.hor...@netronome.com>
Signed-off-by: Louis Peens <louis.pe...@netronome.com>
---
 net/ethtool/channels.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/net/ethtool/channels.c b/net/ethtool/channels.c
index 25a9e566ef5c..e35ef627f61f 100644
--- a/net/ethtool/channels.c
+++ b/net/ethtool/channels.c
@@ -175,14 +175,14 @@ int ethnl_set_channels(struct sk_buff *skb, struct 
genl_info *info)
 
        /* ensure there is at least one RX and one TX channel */
        if (!channels.combined_count && !channels.rx_count)
-               err_attr = tb[ETHTOOL_A_CHANNELS_RX_COUNT];
+               err_attr = mod_combined ? tb[ETHTOOL_A_CHANNELS_COMBINED_COUNT] 
:
+                                         tb[ETHTOOL_A_CHANNELS_RX_COUNT];
        else if (!channels.combined_count && !channels.tx_count)
-               err_attr = tb[ETHTOOL_A_CHANNELS_TX_COUNT];
+               err_attr = mod_combined ? tb[ETHTOOL_A_CHANNELS_COMBINED_COUNT] 
:
+                                         tb[ETHTOOL_A_CHANNELS_TX_COUNT];
        else
                err_attr = NULL;
        if (err_attr) {
-               if (mod_combined)
-                       err_attr = tb[ETHTOOL_A_CHANNELS_COMBINED_COUNT];
                ret = -EINVAL;
                NL_SET_ERR_MSG_ATTR(info->extack, err_attr, "requested channel 
counts would result in no RX or TX channel being configured");
                goto out_ops;
-- 
2.20.1