ethtool: fix the check logic of at least one channel for RX/TX

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.zhang@corigine.com>
Signed-off-by: Simon Horman <simon.horman@netronome.com>
Signed-off-by: Louis Peens <louis.peens@netronome.com>
Link: https://lore.kernel.org/r/20210225125102.23989-1-simon.horman@netronome.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/ethtool/channels.c b/net/ethtool/channels.c
index 25a9e566ef5cdd45c3e1c460fb6bf1c3404b6b5c..6a070dc8e4b0dba90656d92f742320200c6bdfe3 100644 (file)
--- a/net/ethtool/channels.c
+++ b/net/ethtool/channels.c
@@ -116,10 +116,9 @@ int ethnl_set_channels(struct sk_buff *skb, struct genl_info *info)
        struct ethtool_channels channels = {};
        struct ethnl_req_info req_info = {};
        struct nlattr **tb = info->attrs;
-       const struct nlattr *err_attr;
+       u32 err_attr, max_rx_in_use = 0;
        const struct ethtool_ops *ops;
        struct net_device *dev;
-       u32 max_rx_in_use = 0;
        int ret;
 
        ret = ethnl_parse_header_dev_get(&req_info,
@@ -157,34 +156,35 @@ int ethnl_set_channels(struct sk_buff *skb, struct genl_info *info)
 
        /* ensure new channel counts are within limits */
        if (channels.rx_count > channels.max_rx)
-               err_attr = tb[ETHTOOL_A_CHANNELS_RX_COUNT];
+               err_attr = ETHTOOL_A_CHANNELS_RX_COUNT;
        else if (channels.tx_count > channels.max_tx)
-               err_attr = tb[ETHTOOL_A_CHANNELS_TX_COUNT];
+               err_attr = ETHTOOL_A_CHANNELS_TX_COUNT;
        else if (channels.other_count > channels.max_other)
-               err_attr = tb[ETHTOOL_A_CHANNELS_OTHER_COUNT];
+               err_attr = ETHTOOL_A_CHANNELS_OTHER_COUNT;
        else if (channels.combined_count > channels.max_combined)
-               err_attr = tb[ETHTOOL_A_CHANNELS_COMBINED_COUNT];
+               err_attr = ETHTOOL_A_CHANNELS_COMBINED_COUNT;
        else
-               err_attr = NULL;
+               err_attr = 0;
        if (err_attr) {
                ret = -EINVAL;
-               NL_SET_ERR_MSG_ATTR(info->extack, err_attr,
+               NL_SET_ERR_MSG_ATTR(info->extack, tb[err_attr],
                                    "requested channel count exceeds maximum");
                goto out_ops;
        }
 
        /* 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 = ETHTOOL_A_CHANNELS_RX_COUNT;
        else if (!channels.combined_count && !channels.tx_count)
-               err_attr = tb[ETHTOOL_A_CHANNELS_TX_COUNT];
+               err_attr = ETHTOOL_A_CHANNELS_TX_COUNT;
        else
-               err_attr = NULL;
+               err_attr = 0;
        if (err_attr) {
                if (mod_combined)
-                       err_attr = tb[ETHTOOL_A_CHANNELS_COMBINED_COUNT];
+                       err_attr = 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");
+               NL_SET_ERR_MSG_ATTR(info->extack, tb[err_attr],
+                                   "requested channel counts would result in no RX or TX channel being configured");
                goto out_ops;
        }