[PATCH net-next v2] netdev-genl: Elide napi_id when not present

[Joe Damato]

There are at least two cases where napi_id may not present and the
napi_id should be elided:

1. Queues could be created, but napi_enable may not have been called
   yet. In this case, there may be a NAPI but it may not have an ID and
   output of a napi_id should be elided.

2. TX-only NAPIs currently do not have NAPI IDs. If a TX queue happens
   to be linked with a TX-only NAPI, elide the NAPI ID from the netlink
   output as a NAPI ID of 0 is not useful for users.

Signed-off-by: Joe Damato <jdamato@xxxxxxxxxx>
---
 v2:
   - Updated to elide NAPI IDs for RX queues which may have not called
     napi_enable yet.

 rfc: https://lore.kernel.org/lkml/20250128163038.429864-1-jdamato@xxxxxxxxxx/
 net/core/netdev-genl.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/net/core/netdev-genl.c b/net/core/netdev-genl.c
index 715f85c6b62e..a97d3b99f6cd 100644
--- a/net/core/netdev-genl.c
+++ b/net/core/netdev-genl.c
@@ -385,9 +385,10 @@ netdev_nl_queue_fill_one(struct sk_buff *rsp, struct net_device *netdev,
 	switch (q_type) {
 	case NETDEV_QUEUE_TYPE_RX:
 		rxq = __netif_get_rx_queue(netdev, q_idx);
-		if (rxq->napi && nla_put_u32(rsp, NETDEV_A_QUEUE_NAPI_ID,
-					     rxq->napi->napi_id))
-			goto nla_put_failure;
+		if (rxq->napi && rxq->napi->napi_id >= MIN_NAPI_ID)
+			if (nla_put_u32(rsp, NETDEV_A_QUEUE_NAPI_ID,
+					rxq->napi->napi_id))
+				goto nla_put_failure;
 
 		binding = rxq->mp_params.mp_priv;
 		if (binding &&
@@ -397,9 +398,10 @@ netdev_nl_queue_fill_one(struct sk_buff *rsp, struct net_device *netdev,
 		break;
 	case NETDEV_QUEUE_TYPE_TX:
 		txq = netdev_get_tx_queue(netdev, q_idx);
-		if (txq->napi && nla_put_u32(rsp, NETDEV_A_QUEUE_NAPI_ID,
-					     txq->napi->napi_id))
-			goto nla_put_failure;
+		if (txq->napi && txq->napi->napi_id >= MIN_NAPI_ID)
+			if (nla_put_u32(rsp, NETDEV_A_QUEUE_NAPI_ID,
+					txq->napi->napi_id))
+				goto nla_put_failure;
 	}
 
 	genlmsg_end(rsp, hdr);

base-commit: c2933b2befe25309f4c5cfbea0ca80909735fd76
-- 
2.25.1