On Thu, Jan 07, 2021 at 12:18:28PM +0100, Eric Dumazet wrote: > What a mess really.
Thanks, that's at least _some_ feedback :) > You chose to keep the assumption that ndo_get_stats() would not fail, > since we were providing the needed storage from callers. > > If ndo_get_stats() are now allowed to sleep, and presumably allocate > memory, we need to make sure > we report potential errors back to the user. > > I think your patch series is mostly good, but I would prefer not > hiding errors and always report them to user space. > And no, netdev_err() is not appropriate, we do not want tools to look > at syslog to guess something went wrong. Well, there are only 22 dev_get_stats callers in the kernel, so I assume that after the conversion to return void, I can do another conversion to return int, and then I can convert the ndo_get_stats64 method to return int too. I will keep the plain ndo_get_stats still void (no reason not to). > Last point about drivers having to go to slow path, talking to > firmware : Make sure that malicious/innocent users > reading /proc/net/dev from many threads in parallel wont brick these devices. > > Maybe they implicitly _relied_ on the fact that firmware was gently > read every second and results were cached from a work queue or > something. How? I don't understand how I can make sure of that. There is an effort initiated by Jakub to standardize the ethtool statistics. My objection was that you can't expect that to happen unless dev_get_stats is sleepable just like ethtool -S is. So I think the same reasoning should apply to ethtool -S too, really.
