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

["Samudrala, Sridhar" <sridhar.samudrala@intel.com>]

On 2/3/2025 11:17 AM, Joe Damato wrote:
> 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@fastly.com>

Reviewed-by: Sridhar Samudrala <sridhar.samudrala@intel.com>

> ---
>   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@fastly.com/
>   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