Re: [patch net-next 00/34] net: sched: allow qdiscs to share filter block instances

[David Ahern <dsahern@gmail.com>]

On 10/12/17 11:17 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 
> 
> Now we can add filter to any of qdiscs sharing the same block:
> 
> $ tc filter add dev ens7 parent ffff: protocol ip pref 25 flower dst_ip 192.168.0.0/16 action drop
> 
> 
> We will see the same output if we list filters for ens7 and ens8, including stats:
> 
> $ tc -s filter show dev ens7 ingress
> filter protocol ip pref 25 flower chain 0 
> filter protocol ip pref 25 flower chain 0 handle 0x1 
>   eth_type ipv4
>   dst_ip 192.168.0.0/16
>   not_in_hw
>         action order 1: gact action drop
>          random type none pass val 0
>          index 1 ref 1 bind 1 installed 39 sec used 2 sec
>         Action statistics:
>         Sent 3108 bytes 37 pkt (dropped 37, overlimits 0 requeues 0) 
>         backlog 0b 0p requeues 0 
> 
> $ tc -s filter show dev ens8 ingress
> filter protocol ip pref 25 flower chain 0 
> filter protocol ip pref 25 flower chain 0 handle 0x1 
>   eth_type ipv4
>   dst_ip 192.168.0.0/16
>   not_in_hw
>         action order 1: gact action drop
>          random type none pass val 0
>          index 1 ref 1 bind 1 installed 40 sec used 3 sec
>         Action statistics:
>         Sent 3108 bytes 37 pkt (dropped 37, overlimits 0 requeues 0) 
>         backlog 0b 0p requeues 0

This seems like really odd semantics to me ... a filter added to one
device shows up on another.

Why not make the shared block a standalone object that is configured
through its own set of commands and then referenced by both devices?