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Date: Thu, 29 Sep 2022 15:24:06 +0200
From: Andrew Lunn <andrew@lunn.ch>
To: Shenwei Wang <shenwei.wang@nxp.com>
Cc: Joakim Zhang <qiangqing.zhang@nxp.com>,
	"David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Jesper Dangaard Brouer <hawk@kernel.org>,
	John Fastabend <john.fastabend@gmail.com>,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"imx@lists.linux.dev" <imx@lists.linux.dev>
Subject: Re: [EXT] Re: [PATCH 1/1] net: fec: add initial XDP support
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References: <20220928152509.141490-1-shenwei.wang@nxp.com>
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> > > +struct fec_enet_xdp_stats {
> > > +     u64     xdp_pass;
> > > +     u64     xdp_drop;
> > > +     u64     xdp_xmit;
> > > +     u64     xdp_redirect;
> > > +     u64     xdp_xmit_err;
> > > +     u64     xdp_tx;
> > > +     u64     xdp_tx_err;
> > > +};
> > > +
> > > +     switch (act) {
> > > +     case XDP_PASS:
> > > +             rxq->stats.xdp_pass++;
> > 
> > Since the stats are u64, and most machines using the FEC are 32 bit, you cannot
> > just do an increment. Took a look at u64_stats_sync.h.
> > 
> 

> As this increment is only executed under the NAPI kthread context,
> is the protection still required?

Are the statistics values read by ethtool under NAPI kthread context?

    Andrew