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Date:   Tue, 6 Dec 2022 19:08:01 +0200
From:   Vladimir Oltean <olteanv@gmail.com>
To:     Oleksij Rempel <o.rempel@pengutronix.de>
Cc:     Woojung Huh <woojung.huh@microchip.com>,
        UNGLinuxDriver@microchip.com, Andrew Lunn <andrew@lunn.ch>,
        Vivien Didelot <vivien.didelot@gmail.com>,
        Florian Fainelli <f.fainelli@gmail.com>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>, kernel@pengutronix.de,
        linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
        Arun.Ramadoss@microchip.com
Subject: Re: [PATCH net-next v1 1/1] net: dsa: microchip: add stats64 support
 for ksz8 series of switches
Message-ID: <20221206170801.othuifyrm3qrz7ub@skbuf>
References: <20221205052904.2834962-1-o.rempel@pengutronix.de>
 <20221205052904.2834962-1-o.rempel@pengutronix.de>
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 <20221205052904.2834962-1-o.rempel@pengutronix.de>
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On Mon, Dec 05, 2022 at 06:29:04AM +0100, Oleksij Rempel wrote:
> +void ksz88xx_r_mib_stats64(struct ksz_device *dev, int port)
> +{
> +	struct ethtool_pause_stats *pstats;
> +	struct rtnl_link_stats64 *stats;
> +	struct ksz88xx_stats_raw *raw;
> +	struct ksz_port_mib *mib;
> +
> +	mib = &dev->ports[port].mib;
> +	stats = &mib->stats64;
> +	pstats = &mib->pause_stats;
> +	raw = (struct ksz88xx_stats_raw *)mib->counters;
> +
> +	spin_lock(&mib->stats64_lock);
> +
> +	stats->rx_packets = raw->rx_bcast + raw->rx_mcast + raw->rx_ucast +
> +		raw->rx_pause;
> +	stats->tx_packets = raw->tx_bcast + raw->tx_mcast + raw->tx_ucast +
> +		raw->tx_pause;
> +
> +	/* HW counters are counting bytes + FCS which is not acceptable
> +	 * for rtnl_link_stats64 interface
> +	 */
> +	stats->rx_bytes = raw->rx + raw->rx_hi - stats->rx_packets * ETH_FCS_LEN;
> +	stats->tx_bytes = raw->tx + raw->tx_hi - stats->tx_packets * ETH_FCS_LEN;

What are rx_hi, tx_hi compared to rx, tx?

> +
> +	stats->rx_length_errors = raw->rx_undersize + raw->rx_fragments +
> +		raw->rx_oversize;
> +
> +	stats->rx_crc_errors = raw->rx_crc_err;
> +	stats->rx_frame_errors = raw->rx_align_err;
> +	stats->rx_dropped = raw->rx_discards;
> +	stats->rx_errors = stats->rx_length_errors + stats->rx_crc_errors +
> +		stats->rx_frame_errors  + stats->rx_dropped;
> +
> +	stats->tx_window_errors = raw->tx_late_col;
> +	stats->tx_fifo_errors = raw->tx_discards;
> +	stats->tx_aborted_errors = raw->tx_exc_col;
> +	stats->tx_errors = stats->tx_window_errors + stats->tx_fifo_errors +
> +		stats->tx_aborted_errors;
> +
> +	stats->multicast = raw->rx_mcast;
> +	stats->collisions = raw->tx_total_col;
> +
> +	pstats->tx_pause_frames = raw->tx_pause;
> +	pstats->rx_pause_frames = raw->rx_pause;

FWIW, ksz_get_pause_stats() can sleep, just ksz_get_stats64() can't. So
the pause stats don't need to be periodically read (unless you want to
do that to prevent 32-bit overflows).

> +
> +	spin_unlock(&mib->stats64_lock);
> +}