[net-next,5/7] netdevsim: report stats by default, like a real device

Real devices should implement qstats. Devices which support
pause or FEC configuration should also report the relevant stats.

nsim was missing FEC stats completely, some of the qstats
and pause stats required toggling a debugfs knob.

Note that the tests which used pause always initialize the setting
so they shouldn't be affected by the different starting value.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---
 drivers/net/netdevsim/ethtool.c | 11 ++++++++
 drivers/net/netdevsim/netdev.c  | 45 +++++++++++++++++++++++++++++++++
 2 files changed, 56 insertions(+)

On 2024-04-01 18:05, Jakub Kicinski wrote:
> Real devices should implement qstats. Devices which support
> pause or FEC configuration should also report the relevant stats.
> 
> nsim was missing FEC stats completely, some of the qstats
> and pause stats required toggling a debugfs knob.
> 
> Note that the tests which used pause always initialize the setting
> so they shouldn't be affected by the different starting value.
> 
> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
> ---
>  drivers/net/netdevsim/ethtool.c | 11 ++++++++
>  drivers/net/netdevsim/netdev.c  | 45 +++++++++++++++++++++++++++++++++
>  2 files changed, 56 insertions(+)
> 
> diff --git a/drivers/net/netdevsim/ethtool.c b/drivers/net/netdevsim/ethtool.c
> index bd546d4d26c6..3f9c9327f149 100644
> --- a/drivers/net/netdevsim/ethtool.c
> +++ b/drivers/net/netdevsim/ethtool.c
> @@ -140,6 +140,13 @@ nsim_set_fecparam(struct net_device *dev, struct ethtool_fecparam *fecparam)
>  	return 0;
>  }
>  
> +static void
> +nsim_get_fec_stats(struct net_device *dev, struct ethtool_fec_stats *fec_stats)
> +{
> +	fec_stats->corrected_blocks.total = 123;
> +	fec_stats->uncorrectable_blocks.total = 4;
> +}
> +
>  static int nsim_get_ts_info(struct net_device *dev,
>  			    struct ethtool_ts_info *info)
>  {
> @@ -163,6 +170,7 @@ static const struct ethtool_ops nsim_ethtool_ops = {
>  	.set_channels			= nsim_set_channels,
>  	.get_fecparam			= nsim_get_fecparam,
>  	.set_fecparam			= nsim_set_fecparam,
> +	.get_fec_stats			= nsim_get_fec_stats,
>  	.get_ts_info			= nsim_get_ts_info,
>  };
>  
> @@ -182,6 +190,9 @@ void nsim_ethtool_init(struct netdevsim *ns)
>  
>  	nsim_ethtool_ring_init(ns);
>  
> +	ns->ethtool.pauseparam.report_stats_rx = true;
> +	ns->ethtool.pauseparam.report_stats_tx = true;
> +
>  	ns->ethtool.fec.fec = ETHTOOL_FEC_NONE;
>  	ns->ethtool.fec.active_fec = ETHTOOL_FEC_NONE;
>  
> diff --git a/drivers/net/netdevsim/netdev.c b/drivers/net/netdevsim/netdev.c
> index 8330bc0bcb7e..096ac0abbc02 100644
> --- a/drivers/net/netdevsim/netdev.c
> +++ b/drivers/net/netdevsim/netdev.c
> @@ -19,6 +19,7 @@
>  #include <linux/module.h>
>  #include <linux/netdevice.h>
>  #include <linux/slab.h>
> +#include <net/netdev_queues.h>
>  #include <net/netlink.h>
>  #include <net/pkt_cls.h>
>  #include <net/rtnetlink.h>
> @@ -330,6 +331,49 @@ static const struct net_device_ops nsim_vf_netdev_ops = {
>  	.ndo_set_features	= nsim_set_features,
>  };
>  
> +/* We don't have true par-queue stats, yet, so do some random fakery here. */

nit: per-queue

> +static void nsim_get_queue_stats_rx(struct net_device *dev, int idx,
> +				    struct netdev_queue_stats_rx *stats)
> +{
> +	struct rtnl_link_stats64 rtstats = {};
> +
> +	nsim_get_stats64(dev, &rtstats);
> +
> +	stats->packets = rtstats.rx_packets - !!rtstats.rx_packets;

Why subtract !!rtstats.rx_packets? This evaluates to 0 if rx_packets is
0 and 1 if rx_packets is non-zero.

> +	stats->bytes = rtstats.rx_bytes;
> +}
> +
> +static void nsim_get_queue_stats_tx(struct net_device *dev, int idx,
> +				    struct netdev_queue_stats_tx *stats)
> +{
> +	struct rtnl_link_stats64 rtstats = {};
> +
> +	nsim_get_stats64(dev, &rtstats);
> +
> +	stats->packets = rtstats.tx_packets - !!rtstats.tx_packets;
> +	stats->bytes = rtstats.tx_bytes;
> +}
> +
> +static void nsim_get_base_stats(struct net_device *dev,
> +				struct netdev_queue_stats_rx *rx,
> +				struct netdev_queue_stats_tx *tx)
> +{
> +	struct rtnl_link_stats64 rtstats = {};
> +
> +	nsim_get_stats64(dev, &rtstats);
> +
> +	rx->packets = !!rtstats.rx_packets;
> +	rx->bytes = 0;
> +	tx->packets = !!rtstats.tx_packets;
> +	tx->bytes = 0;
> +}
> +
> +static const struct netdev_stat_ops nsim_stat_ops = {
> +	.get_queue_stats_tx	= nsim_get_queue_stats_tx,
> +	.get_queue_stats_rx	= nsim_get_queue_stats_rx,
> +	.get_base_stats		= nsim_get_base_stats,
> +};
> +
>  static void nsim_setup(struct net_device *dev)
>  {
>  	ether_setup(dev);
> @@ -360,6 +404,7 @@ static int nsim_init_netdevsim(struct netdevsim *ns)
>  
>  	ns->phc = phc;
>  	ns->netdev->netdev_ops = &nsim_netdev_ops;
> +	ns->netdev->stat_ops = &nsim_stat_ops;
>  
>  	err = nsim_udp_tunnels_info_create(ns->nsim_dev, ns->netdev);
>  	if (err)