ethtool: netlink: Add missing ethnl_ops_begin/complete

Accessing an ethernet device that is powered off or clock gated might
cause the CPU to hang. Add ethnl_ops_begin/complete in
ethnl_set_features() to protect against this.

Fixes: 0980bfc ("ethtool: set netdev features with FEATURES_SET request")
Signed-off-by: Ludvig Pärsson <ludvig.parsson@axis.com>
Link: https://lore.kernel.org/r/20240117-etht2-v2-1-1a96b6e8c650@axis.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

net/ethtool/features.c

@@ -234,17 +234,20 @@ int ethnl_set_features(struct sk_buff *skb, struct genl_info *info)
 	dev = req_info.dev;
 
 	rtnl_lock();
+	ret = ethnl_ops_begin(dev);
+	if (ret < 0)
+		goto out_rtnl;
 	ethnl_features_to_bitmap(old_active, dev->features);
 	ethnl_features_to_bitmap(old_wanted, dev->wanted_features);
 	ret = ethnl_parse_bitset(req_wanted, req_mask, NETDEV_FEATURE_COUNT,
 				 tb[ETHTOOL_A_FEATURES_WANTED],
 				 netdev_features_strings, info->extack);
 	if (ret < 0)
-		goto out_rtnl;
+		goto out_ops;
 	if (ethnl_bitmap_to_features(req_mask) & ~NETIF_F_ETHTOOL_BITS) {
 		GENL_SET_ERR_MSG(info, "attempt to change non-ethtool features");
 		ret = -EINVAL;
-		goto out_rtnl;
+		goto out_ops;
 	}
 
 	/* set req_wanted bits not in req_mask from old_wanted */
@@ -281,6 +284,8 @@ int ethnl_set_features(struct sk_buff *skb, struct genl_info *info)
 	if (mod)
 		netdev_features_change(dev);
 
+out_ops:
+	ethnl_ops_complete(dev);
 out_rtnl:
 	rtnl_unlock();
 	ethnl_parse_header_dev_put(&req_info);