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Date:   Fri, 4 Dec 2020 23:12:57 +0100
From:   Andrew Lunn <andrew@lunn.ch>
To:     George McCollister <george.mccollister@gmail.com>
Cc:     Oleksij Rempel <o.rempel@pengutronix.de>,
        Vivien Didelot <vivien.didelot@gmail.com>,
        Florian Fainelli <f.fainelli@gmail.com>,
        Vladimir Oltean <olteanv@gmail.com>,
        "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>,
        Russell King <linux@armlinux.org.uk>,
        Pengutronix Kernel Team <kernel@pengutronix.de>,
        netdev@vger.kernel.org, open list <linux-kernel@vger.kernel.org>,
        linux-mips@vger.kernel.org
Subject: Re: [PATCH v4 net-next 2/2] net: dsa: qca: ar9331: export stats64
Message-ID: <20201204221257.GH2400258@lunn.ch>
References: <20201204145624.11713-1-o.rempel@pengutronix.de>
 <20201204145624.11713-3-o.rempel@pengutronix.de>
 <CAFSKS=Pq9=mNXGeTbcTOL-=rp8wWCS2qtHF38eD1HiN=EK0DOQ@mail.gmail.com>
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> > +struct ar9331_sw_stats {
> > +       u64 rxbroad;
> > +       u64 rxpause;
> > +       u64 rxmulti;
> > +};

7> > +struct ar9331_sw_port {
> > +       int idx;
> > +       struct ar9331_sw_priv *priv;
> > +       struct delayed_work mib_read;
> > +       struct ar9331_sw_stats stats;


> > +static void ar9331_stats_update(struct ar9331_sw_port *port,
> > +                               struct rtnl_link_stats64 *stats)
> > +{
> > +       struct ar9331_sw_stats *s = &port->stats;
> > +
> > +       stats->rx_packets = s->rxbroad + s->rxmulti + s->rx64byte +
> > +               s->rx128byte + s->rx256byte + s->rx512byte + s->rx1024byte +
> > +               s->rx1518byte + s->rxmaxbyte;
> 
> Are all of these port->stats accesses always atomic? I'll need to do
> something similar in my xrs700x driver and want to make sure there
> doesn't need to be a lock between here and where they're updated in
> the delayed work.

Since these are u64, they are not atomic on 32 bit systems.

Take a look at

include/linux/u64_stats_sync.h

	Andrewu