Re: [PATCH net-next v17 2/2] hinic3: Add ethtool statistic ops part2

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- [Medium] hinic3_get_pause_stats() can never be called.

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hinic3: Add ethtool statistic ops part2

This commit adds five standard ethtool statistics callbacks to the hinic3
driver: get_eth_phy_stats, get_eth_mac_stats, get_eth_ctrl_stats,
get_rmon_stats and get_pause_stats. Each callback reads the physical port
counters from firmware and copies them into the standard ethtool
structures.

> diff --git a/drivers/net/ethernet/huawei/hinic3/hinic3_ethtool.c b/drivers/net/ethernet/huawei/hinic3/hinic3_ethtool.c
> index 64c862052f1e8..2ae4d5afe90df 100644
> --- a/drivers/net/ethernet/huawei/hinic3/hinic3_ethtool.c
> +++ b/drivers/net/ethernet/huawei/hinic3/hinic3_ethtool.c

[ ... ]

> +static void hinic3_get_pause_stats(struct net_device *netdev,
> +				   struct ethtool_pause_stats *pause_stats)
> +{

[ ... ]

> +	pause_stats->tx_pause_frames = le64_to_cpu(ps->mac_tx_pause_pkts);
> +	pause_stats->rx_pause_frames = le64_to_cpu(ps->mac_rx_pause_pkts);
> +
> +	kfree(ps);
> +}

[ ... ]

> @@ -707,6 +904,11 @@ static const struct ethtool_ops hinic3_ethtool_ops = {
>  	.get_strings                    = hinic3_get_strings,
>  	.get_sset_count                 = hinic3_get_sset_count,
>  	.get_ethtool_stats              = hinic3_get_ethtool_stats,
> +	.get_eth_phy_stats              = hinic3_get_eth_phy_stats,
> +	.get_eth_mac_stats              = hinic3_get_eth_mac_stats,
> +	.get_eth_ctrl_stats             = hinic3_get_eth_ctrl_stats,
> +	.get_rmon_stats                 = hinic3_get_rmon_stats,
> +	.get_pause_stats                = hinic3_get_pause_stats,

[Severity: Medium]
Can hinic3_get_pause_stats() actually be reached by the ethtool core?

hinic3_ethtool_ops sets .get_pause_stats but has no .get_pauseparam, and
nothing under drivers/net/ethernet/huawei/hinic3/ implements one. The
generic caller of get_pause_stats, pause_prepare_data() in
net/ethtool/pause.c, bails out before it gets to the stats callback:

net/ethtool/pause.c:pause_prepare_data() {
    ...
	if (!dev->ethtool_ops->get_pauseparam)
		return -EOPNOTSUPP;
    ...
	dev->ethtool_ops->get_pauseparam(dev, &data->pauseparam);
	if (req_base->flags & ETHTOOL_FLAG_STATS &&
	    dev->ethtool_ops->get_pause_stats)
		dev->ethtool_ops->get_pause_stats(dev, &data->pausestat);
    ...
}

The only other user, ethtool_aggregate_pause_stats(), is a helper that
MAC-merge-capable drivers call themselves, and hinic3 doesn't call it.
Pause stats also aren't one of the ETHTOOL_MSG_STATS_GET groups.

So "ethtool -I -a <dev>" would fail with -EOPNOTSUPP. That means
mac_tx_pause_pkts and mac_rx_pause_pkts never reach userspace, even though
the commit message lists get_pause_stats as one of the five added
callbacks.

The driver already has hinic3_get_pause_info() in hinic3_nic_cfg.c, which
hinic3_ethtool.c already calls elsewhere. Could that be used to add a
get_pauseparam implementation? Otherwise, could get_pause_stats wait until
one exists?

>  };
>  
>  void hinic3_set_ethtool_ops(struct net_device *netdev)

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