On 12/13/17 10:39 AM, Jiri Pirko wrote: > Wed, Dec 13, 2017 at 06:18:04PM CET, dsah...@gmail.com wrote: >> On 12/13/17 10:07 AM, Jiri Pirko wrote: >>> Wed, Dec 13, 2017 at 05:54:35PM CET, dsah...@gmail.com wrote: >>>> On 12/13/17 8:10 AM, Jiri Pirko wrote: >>>>> So back to the example. First, we create 2 qdiscs. Both will share >>>>> block number 22. "22" is just an identification. If we don't pass any >>>>> block number, a new one will be generated by kernel: >>>>> >>>>> $ tc qdisc add dev ens7 ingress block 22 >>>>> ^^^^^^^^ >>>>> $ tc qdisc add dev ens8 ingress block 22 >>>>> ^^^^^^^^ >>>>> >>>>> Now if we list the qdiscs, we will see the block index in the output: >>>>> >>>>> $ tc qdisc >>>>> qdisc ingress ffff: dev ens7 parent ffff:fff1 block 22 >>>>> qdisc ingress ffff: dev ens8 parent ffff:fff1 block 22 >>>>> >>>>> To make is more visual, the situation looks like this: >>>>> >>>>> ens7 ingress qdisc ens7 ingress qdisc >>>>> | | >>>>> | | >>>>> +----------> block 22 <----------+ >>>>> >>>>> Unlimited number of qdiscs may share the same block. >>>>> >>>>> Now we can add filter to any of qdiscs sharing the same block: >>>>> >>>>> $ tc filter add dev ens7 ingress protocol ip pref 25 flower dst_ip >>>>> 192.168.0.0/16 action drop >>>> >>>> I still say this is very odd user semantic - making changes to device M >>>> and the changes magically affect device N. Operating on the shared block >>>> as a separate object makes it is much more direct and clear. >>> >>> I plan to do it as a follow-up patch. But this is how things are done >>> now and have to continue to work. >> >> Why is that? You are introducing the notion of a shared block with this >> patch set. What is the legacy "how things are done now" you are >> referring to? > > Well, the filter add/del should just work no matter if the block behind is > shared or not.
My argument is that modifying a shared block instance via a dev should not be allowed. Those changes should only be allowed via the shared block. So if a user puts adds a shared block to the device and then attempts to add a filter via the device it should not be allowed.
