Re: [PATCH net-next v2 2/3] net: dsa: add Arrow SpeedChips XRS700x driver

What is it with my email today, didn't get this one again.

On Sat, 28 Nov 2020 01:39:16 +0200 Vladimir Oltean wrote:

On Sat, Nov 28, 2020 at 12:30:48AM +0100, Andrew Lunn wrote:

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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.

Just to avoid breaking the suggestion that seqfiles don't sleep after
.start? Hm. I thought BPF slept (or did cond_reshed()) in the middle of
seq iteration. We should double check that seqfiles really can't sleep.

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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.