Re: [PATCH net-next 1/2] netdev-genl: Add ifname for queue and NAPI APIs

["Nambiar, Amritha" <amritha.nambiar@intel.com>]

On 2/21/2024 7:57 AM, Joe Damato wrote:
> Expose the netdevice name when queue and NAPI netdev-genl APIs are used
> 
> Signed-off-by: Joe Damato <jdamato@fastly.com>
> ---
>   include/uapi/linux/netdev.h |  2 ++
>   net/core/netdev-genl.c      | 22 +++++++++++++++++-----
>   2 files changed, 19 insertions(+), 5 deletions(-)
> 
> diff --git a/include/uapi/linux/netdev.h b/include/uapi/linux/netdev.h
> index 93cb411..80762bc 100644
> --- a/include/uapi/linux/netdev.h
> +++ b/include/uapi/linux/netdev.h
> @@ -117,6 +117,7 @@ enum {
>   	NETDEV_A_NAPI_ID,
>   	NETDEV_A_NAPI_IRQ,
>   	NETDEV_A_NAPI_PID,
> +	NETDEV_A_NAPI_IFNAME,
>   
>   	__NETDEV_A_NAPI_MAX,
>   	NETDEV_A_NAPI_MAX = (__NETDEV_A_NAPI_MAX - 1)
> @@ -127,6 +128,7 @@ enum {
>   	NETDEV_A_QUEUE_IFINDEX,
>   	NETDEV_A_QUEUE_TYPE,
>   	NETDEV_A_QUEUE_NAPI_ID,
> +	NETDEV_A_QUEUE_IFNAME,
>   
>   	__NETDEV_A_QUEUE_MAX,
>   	NETDEV_A_QUEUE_MAX = (__NETDEV_A_QUEUE_MAX - 1)
> diff --git a/net/core/netdev-genl.c b/net/core/netdev-genl.c
> index fd98936..a886e6a 100644
> --- a/net/core/netdev-genl.c
> +++ b/net/core/netdev-genl.c
> @@ -181,6 +181,9 @@ netdev_nl_napi_fill_one(struct sk_buff *rsp, struct napi_struct *napi,
>   	if (nla_put_u32(rsp, NETDEV_A_NAPI_IFINDEX, napi->dev->ifindex))
>   		goto nla_put_failure;
>   
> +	if (nla_put_string(rsp, NETDEV_A_NAPI_IFNAME, napi->dev->name))
> +		goto nla_put_failure;
> +
>   	if (napi->irq >= 0 && nla_put_u32(rsp, NETDEV_A_NAPI_IRQ, napi->irq))
>   		goto nla_put_failure;
>   
> @@ -307,7 +310,8 @@ netdev_nl_queue_fill_one(struct sk_buff *rsp, struct net_device *netdev,
>   
>   	if (nla_put_u32(rsp, NETDEV_A_QUEUE_ID, q_idx) ||
>   	    nla_put_u32(rsp, NETDEV_A_QUEUE_TYPE, q_type) ||
> -	    nla_put_u32(rsp, NETDEV_A_QUEUE_IFINDEX, netdev->ifindex))
> +	    nla_put_u32(rsp, NETDEV_A_QUEUE_IFINDEX, netdev->ifindex) ||
> +	    nla_put_string(rsp, NETDEV_A_QUEUE_IFNAME, netdev->name))
>   		goto nla_put_failure;
>   
>   	switch (q_type) {
> @@ -369,16 +373,19 @@ int netdev_nl_queue_get_doit(struct sk_buff *skb, struct genl_info *info)
>   	u32 q_id, q_type, ifindex;
>   	struct net_device *netdev;
>   	struct sk_buff *rsp;
> +	char *ifname;
>   	int err;
>   
>   	if (GENL_REQ_ATTR_CHECK(info, NETDEV_A_QUEUE_ID) ||
>   	    GENL_REQ_ATTR_CHECK(info, NETDEV_A_QUEUE_TYPE) ||
> -	    GENL_REQ_ATTR_CHECK(info, NETDEV_A_QUEUE_IFINDEX))
> +	    GENL_REQ_ATTR_CHECK(info, NETDEV_A_QUEUE_IFINDEX) ||
> +	    GENL_REQ_ATTR_CHECK(info, NETDEV_A_QUEUE_IFNAME))
>   		return -EINVAL;
>   
>   	q_id = nla_get_u32(info->attrs[NETDEV_A_QUEUE_ID]);
>   	q_type = nla_get_u32(info->attrs[NETDEV_A_QUEUE_TYPE]);
>   	ifindex = nla_get_u32(info->attrs[NETDEV_A_QUEUE_IFINDEX]);
> +	nla_strscpy(ifname, info->attrs[NETDEV_A_QUEUE_IFNAME], IFNAMSIZ);
>   
>   	rsp = genlmsg_new(GENLMSG_DEFAULT_SIZE, GFP_KERNEL);
>   	if (!rsp)
> @@ -387,10 +394,15 @@ int netdev_nl_queue_get_doit(struct sk_buff *skb, struct genl_info *info)
>   	rtnl_lock();
>   
>   	netdev = __dev_get_by_index(genl_info_net(info), ifindex);
> -	if (netdev)
> -		err = netdev_nl_queue_fill(rsp, netdev, q_id, q_type, info);
> -	else
> +
> +	if (strcmp(netdev->name, ifname)) {
>   		err = -ENODEV;
> +	} else {
> +		if (netdev)
> +			err = netdev_nl_queue_fill(rsp, netdev, q_id, q_type, info);
> +		else
> +			err = -ENODEV;
> +	}
>   

This looks bit incorrect to me that the netdev is checked after 
netdev->name is accessed. Shouldn't this be something like:

if (netdev && !strcmp(netdev->name, ifname))
	err = netdev_nl_queue_fill(rsp, netdev, q_id, q_type, info);
else
	err = -ENODEV;

>   	rtnl_unlock();
>