netdev - Re: [PATCH] net: mvpp2: add ethtool GOP statistics

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Date:   Thu, 2 Nov 2017 20:58:27 +0100
From:   Andrew Lunn <andrew@...n.ch>
To:     Miquel Raynal <miquel.raynal@...e-electrons.com>
Cc:     "David S . Miller" <davem@...emloft.net>,
        Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>,
        Antoine Tenart <antoine.tenart@...e-electrons.com>,
        Gregory Clement <gregory.clement@...e-electrons.com>,
        Nadav Haklai <nadavh@...vell.com>, netdev@...r.kernel.org,
        Stefan Chulski <stefanc@...vell.com>
Subject: Re: [PATCH] net: mvpp2: add ethtool GOP statistics

Hi Miquel

> +static struct mvpp2_ethtool_statistics mvpp2_ethtool_stats[] = {

This can probably be const, and save a few bytes of RAM.

> +	{ MVPP2_MIB_GOOD_OCTETS_RCVD_LOW, "good_octets_received" },
> +	{ MVPP2_MIB_BAD_OCTETS_RCVD, "bad_octets_received" },
> +	{ MVPP2_MIB_CRC_ERRORS_SENT, "crc_errors_sent" },
> +	{ MVPP2_MIB_UNICAST_FRAMES_RCVD, "unicast_frames_received" },
> +	{ MVPP2_MIB_BROADCAST_FRAMES_RCVD, "broadcast_frames_received" },
> +	{ MVPP2_MIB_MULTICAST_FRAMES_RCVD, "multicast_frames_received" },
> +	{ MVPP2_MIB_FRAMES_64_OCTETS, "frames_64_octets" },
> +	{ MVPP2_MIB_FRAMES_65_TO_127_OCTETS, "frames_65_to_127_octet" },
> +	{ MVPP2_MIB_FRAMES_128_TO_255_OCTETS, "frames_128_to_255_octet" },
> +	{ MVPP2_MIB_FRAMES_256_TO_511_OCTETS, "frames_256_to_511_octet" },
> +	{ MVPP2_MIB_FRAMES_512_TO_1023_OCTETS, "frames_512_to_1023_octet" },
> +	{ MVPP2_MIB_FRAMES_1024_TO_MAX_OCTETS, "frames_1024_to_max_octet" },
> +	{ MVPP2_MIB_GOOD_OCTETS_SENT_LOW, "good_octets_sent" },
> +	{ MVPP2_MIB_UNICAST_FRAMES_SENT, "unicast_frames_sent" },
> +	{ MVPP2_MIB_MULTICAST_FRAMES_SENT, "multicast_frames_sent" },
> +	{ MVPP2_MIB_BROADCAST_FRAMES_SENT, "broadcast_frames_sent" },
> +	{ MVPP2_MIB_FC_SENT, "fc_sent" },
> +	{ MVPP2_MIB_FC_RCVD, "fc_received" },
> +	{ MVPP2_MIB_RX_FIFO_OVERRUN, "rx_fifo_overrun" },
> +	{ MVPP2_MIB_UNDERSIZE_RCVD, "undersize_received" },
> +	{ MVPP2_MIB_FRAGMENTS_RCVD, "fragments_received" },
> +	{ MVPP2_MIB_OVERSIZE_RCVD, "oversize_received" },
> +	{ MVPP2_MIB_JABBER_RCVD, "jabber_received" },
> +	{ MVPP2_MIB_MAC_RCV_ERROR, "mac_receive_error" },
> +	{ MVPP2_MIB_BAD_CRC_EVENT, "bad_crc_event" },
> +	{ MVPP2_MIB_COLLISION, "collision" },
> +	{ MVPP2_MIB_LATE_COLLISION, "late_collision" },
> +};


> +static void mvpp2_gather_hw_statistics(struct work_struct *work)
> +{
> +	struct delayed_work *del_work = to_delayed_work(work);
> +	struct mvpp2 *priv = container_of(del_work, struct mvpp2, stats_work);
> +	struct mvpp2_port *port;
> +	u64 *pstats;
> +	int i, j;
> +
> +	for (i = 0; i < priv->port_count; i++) {
> +		if (!priv->port_list[i])
> +			continue;
> +
> +		port = priv->port_list[i];
> +		pstats = port->ethtool_stats;
> +		for (j = 0; j < ARRAY_SIZE(mvpp2_ethtool_stats); j++)
> +			*pstats++ += mvpp2_read_count(
> +				port, mvpp2_ethtool_stats[j].offset);
> +	}
> +
> +	/* No need to read again the counters right after this function if it
> +	 * was called asynchronously by the user (ie. use of ethtool).
> +	 */
> +	cancel_delayed_work(&priv->stats_work);
> +	queue_delayed_work(priv->stats_queue, &priv->stats_work,
> +			   MVPP2_MIB_COUNTERS_STATS_DELAY);
> +}
> +
> +static void mvpp2_ethtool_get_stats(struct net_device *dev,
> +				    struct ethtool_stats *stats, u64 *data)
> +{
> +	struct mvpp2_port *port = netdev_priv(dev);
> +
> +	/* Update statistics for all ports, copy only those actually needed */
> +	mvpp2_gather_hw_statistics(&port->priv->stats_work.work);

Shouldn't there be some locking here? What if
mvpp2_gather_hw_statistic is already running?

> @@ -7613,13 +7788,19 @@ static int mvpp2_port_probe(struct platform_device *pdev,
>  		port->base = priv->iface_base + MVPP22_GMAC_BASE(port->gop_id);
>  	}
>  
> -	/* Alloc per-cpu stats */
> +	/* Alloc per-cpu and ethtool stats */
>  	port->stats = netdev_alloc_pcpu_stats(struct mvpp2_pcpu_stats);
>  	if (!port->stats) {
>  		err = -ENOMEM;
>  		goto err_free_irq;
>  	}
>  
> +	port->ethtool_stats = kzalloc(sizeof(mvpp2_ethtool_stats), GFP_KERNEL);

devm_ to make the cleanup simpler?

> +	/* This work recall himself within a delay. If the cancellation returned
> +	 * a non-zero value, it means a work is still running. In that case, use
> +	 * use the flush (returns when the running work will be done) and cancel

One use is enough.

> +	 * the new work that was just submitted to the queue but not started yet
> +	 * due to the delay.
> +	 */
> +	if (!cancel_delayed_work(&priv->stats_work)) {
> +		flush_workqueue(priv->stats_queue);
> +		cancel_delayed_work(&priv->stats_work);
> +	}

Why is cancel_delayed_work_sync() not enough?

    Andrew