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Date:   Sat, 28 Nov 2020 00:30:48 +0100
From:   Andrew Lunn <andrew@lunn.ch>
To:     Jakub Kicinski <kuba@kernel.org>
Cc:     George McCollister <george.mccollister@gmail.com>,
        Vladimir Oltean <olteanv@gmail.com>,
        Vivien Didelot <vivien.didelot@gmail.com>,
        Florian Fainelli <f.fainelli@gmail.com>,
        "David S . Miller" <davem@davemloft.net>, netdev@vger.kernel.org,
        "open list:OPEN FIRMWARE AND..." <devicetree@vger.kernel.org>
Subject: Re: [PATCH net-next v2 2/3] net: dsa: add Arrow SpeedChips XRS700x
 driver
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> If there is a better alternative I'm all ears but having /proc and
> ifconfig return zeros for error counts while ip link doesn't will lead
> to too much confusion IMO. While delayed update of stats is a fact of
> life for _years_ now (hence it was backed into the ethtool -C API).

How about dev_seq_start() issues a netdev notifier chain event, asking
devices which care to update their cached rtnl_link_stats64 counters.
They can decide if their cache is too old, and do a blocking read for
new values.

Once the notifier has completed, dev_seq_start() can then
rcu_read_lock() and do the actual collection of stats from the drivers
non-blocking.

	Andrew