Re: [PATCH] backports: mac80211: revert to old stats behaviour for older kernels

[Johannes Berg <johannes@sipsolutions.net>]

On Sun, 2015-05-03 at 21:49 +0200, Arend van Spriel wrote:

> I don't either, but I had a bunch of test systems that I wanted to get 
> going.

While on vacation? :)

> > What part of this isn't supported? Is there no pointer whatsoever that
> > we can use? We still implement the ndo_getstats64 [or whatever it's
> > called] ourselves anyway, so we don't really use any API here apart from
> >   * netdev_alloc_pcpu_stats, which is trivially backported
> >   * dev->tstats, which is just a single pointer and we could use anything
> > else,
> >     even perhaps in sdata
> 
> I have to learn about the per-cpu operations someday so why not now 
> while spending two weeks vacation ;-)

Heh. Go enjoy your vacation, I can handle this :)

I think you arrived at kernel 3.14 due to 8f84985fec10d. However, I
think we can just do the following

 * backport "struct pcpu_sw_netstats" (needed on < 3.14)
 * backport "netdev_alloc_pcpu_stats" (needed on < 3.15)
 * make an spatch replacing dev->tstats with ((struct pcpu_sw_netstats *)dev->ml_priv)
   (since ml_priv has existed for a long time, and they're in a union)

johannes