On Thu, 7 Sep 2017 11:10:33 +0200, Jiri Pirko wrote: > Hi Kuba. > > I'm looking into cls_bpf code and nfp_net_bpf_offload function in your > driver. Why do you need TC_CLSBPF_ADD? Seems like TC_CLSBPF_REPLACE > should be enough. It would make the cls_bpf code easier. > > Note that other cls just have replace/destroy (u32 too, as drivers > handle NEW/REPLACE in one switch-case - will patch this).
Could we clarify what the REPLACE is actually supposed to do? :) In the flower code and the REPLACE looks a lot like ADD on the surface... If change is called it will invoke REPLACE with the new filter and then if there was an old filter, it will do DELETE. Is my understanding correct? If so I found this model of operation somehow confusing. Plus the management of flows may get slightly tricky if there is a possibility of "replacing" a flow with an identical one. Flower may make calls like these: add flower vlan_id 100 action ... # REPLACE vid 100 ... change ... flower vlan_id 100 action ... # REPLACE vid 100 ... # DELETE vid 100 ... Doesn't this force driver/HW to implement refcounting on the rules? On why I need the replace - BPF unlike other classifiers usually installs a single program, I think offloading multiple TC filters is questionable (people will use tailcalls instead most likely). I want to be able to implement atomic replace of that single program (i.e. not ADD followed by DELETE) because that simplifies the driver quite a bit.
