On Tue, Nov 20, 2018 at 3:28 PM David Miller <da...@davemloft.net> wrote:
>
> From: Davide Caratti <dcara...@redhat.com>
> Date: Tue, 20 Nov 2018 22:18:44 +0100
>
> > after 'police' configuration parameters were converted to use RCU instead
> > of spinlock, the state variables used to compute the traffic rate (namely
> > 'tcfp_toks', 'tcfp_ptoks' and 'tcfp_t_c') are erroneously read/updated in
> > the traffic path without any protection.
> >
> > Use a dedicated spinlock to avoid race conditions on these variables, and
> > ensure proper cache-line alignment. In this way, 'police' is still faster
> > than what we observed when 'tcf_lock' was used in the traffic path _ i.e.
> > reverting commit 2d550dbad83c ("net/sched: act_police: don't use spinlock
> > in the data path"). Moreover, we preserve the throughput improvement that
> > was obtained after 'police' started using per-cpu counters, when 'avrate'
> > is used instead of 'rate'.
> >
> > Changes since v1 (thanks to Eric Dumazet):
> > - call ktime_get_ns() before acquiring the lock in the traffic path
> > - use a dedicated spinlock instead of tcf_lock
> > - improve cache-line usage
> >
> > Fixes: 2d550dbad83c ("net/sched: act_police: don't use spinlock in the data
> > path")
> > Reported-and-suggested-by: Eric Dumazet <eric.duma...@gmail.com>
> > Signed-off-by: Davide Caratti <dcara...@redhat.com>
>
> Applied.
We need a fix to make lockdep happy, as reported by Cong.
Cong, do you want to handle this ?
Thanks !
