net: don't dump Tx and uninitialized NAPIs

We use NAPI ID as the key for continuing dumps. We also depend
on the NAPIs being sorted by ID within the driver list. Tx NAPIs
(which don't have an ID assigned) break this expectation, it's
not currently possible to dump them reliably. Since Tx NAPIs
are relatively rare, and can't be used in doit (GET or SET)
hide them from the dump API as well.

Fixes: 27f91aa ("netdev-genl: Add netlink framework functions for napi")
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20250103183207.1216004-1-kuba@kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

net/core/netdev-genl.c

@@ -176,8 +176,7 @@ netdev_nl_napi_fill_one(struct sk_buff *rsp, struct napi_struct *napi,
 	if (!hdr)
 		return -EMSGSIZE;
 
-	if (napi->napi_id >= MIN_NAPI_ID &&
-	    nla_put_u32(rsp, NETDEV_A_NAPI_ID, napi->napi_id))
+	if (nla_put_u32(rsp, NETDEV_A_NAPI_ID, napi->napi_id))
 		goto nla_put_failure;
 
 	if (nla_put_u32(rsp, NETDEV_A_NAPI_IFINDEX, napi->dev->ifindex))
@@ -272,6 +271,8 @@ netdev_nl_napi_dump_one(struct net_device *netdev, struct sk_buff *rsp,
 		return err;
 
 	list_for_each_entry(napi, &netdev->napi_list, dev_list) {
+		if (napi->napi_id < MIN_NAPI_ID)
+			continue;
 		if (ctx->napi_id && napi->napi_id >= ctx->napi_id)
 			continue;