On Wed 17 Apr 2019 at 19:34, Jakub Kicinski <jakub.kicin...@netronome.com>
wrote:
> On Wed, 17 Apr 2019 07:29:36 +0000, Vlad Buslov wrote:
>> On Wed 17 Apr 2019 at 00:49, Jakub Kicinski <jakub.kicin...@netronome.com>
>> wrote:
>> > On Tue, 16 Apr 2019 17:20:47 +0300, Vlad Buslov wrote:
>> >> @@ -1551,6 +1558,10 @@ static int fl_change(struct net *net, struct
>> >> sk_buff *in_skb,
>> >> goto errout_mask;
>> >>
>> >> if (!tc_skip_hw(fnew->flags)) {
>> >> + spin_lock(&tp->lock);
>> >> + list_add(&fnew->hw_list, &head->hw_filters);
>> >> + spin_unlock(&tp->lock);
>> >> +
>> >> err = fl_hw_replace_filter(tp, fnew, rtnl_held, extack);
>> >> if (err)
>> >> goto errout_ht;
>> >
>> > Duplicated deletes should be fine, but I'm not sure same is true for
>> > adds. Won't seeing an add with the same cookie twice confuse drivers?
>> >
>> > There's also the minor issue of offloaded count being off in that
>> > case :)
>>
>> Hmmm, okay. Rejecting duplicate cookies should be a trivial change to
>> drivers though. Do you see any faults with this approach in general?
>
> Trivial or not it adds up, the stack should make driver authors' job as
> easy as possible. The simplest thing to do would be to add a mutex
Agree. However, all driver flower offload implementations already have
all necessary functionality to lookup flow by cookie because they need
it to implement flow deletion.
> around the HW calls. But that obviously doesn't work for you, cause
> you want multiple outstanding requests to the FW for a single tp,
> right?
Right.
>
> How about a RW lock, that would take R on normal add/replace/del paths
> and W on replays? That should scale, no?
Yes. But I would prefer to avoid adding another sleeping lock on
rule update path of every filter (including non-offloaded use cases when
reoffload is not used at all).
Jiri, what approach would you prefer?
