Merge branch 'net-sched-allow-qdiscs-to-share-filter-block-instances'

Jiri Pirko says:

====================
net: sched: allow qdiscs to share filter block instances

Currently the filters added to qdiscs are independent. So for example if you
have 2 netdevices and you create ingress qdisc on both and you want to add
identical filter rules both, you need to add them twice. This patchset
makes this easier and mainly saves resources allowing to share all filters
within a qdisc - I call it a "filter block". Also this helps to save
resources when we do offload to hw for example to expensive TCAM.

So back to the example. First, we create 2 qdiscs. Both will share
block number 22. "22" is just an identification:
$ tc qdisc add dev ens7 ingress_block 22 ingress
                        ^^^^^^^^^^^^^^^^
$ tc qdisc add dev ens8 ingress_block 22 ingress
                        ^^^^^^^^^^^^^^^^

If we don't specify "block" command line option, no shared block would
be created:
$ tc qdisc add dev ens9 ingress

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 ingress_block 22
qdisc ingress ffff: dev ens8 parent ffff:fff1 ingress_block 22
qdisc ingress ffff: dev ens9 parent ffff:fff1

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.

Note that this patchset introduces block sharing support also for clsact
qdisc:
$ tc qdisc add dev ens10 ingress_block 23 egress_block 24 clsact
$ tc qdisc show dev ens10
qdisc clsact ffff: dev ens10 parent ffff:fff1 ingress_block 23 egress_block 24

We can add filter using the block index:

$ tc filter add block 22 protocol ip pref 25 flower dst_ip 192.168.0.0/16 action drop

Note we cannot use the qdisc for filter manipulations of shared blocks:

$ tc filter add dev ens8 ingress protocol ip pref 1 flower dst_ip 192.168.100.2 action drop
Error: This filter block is shared. Please use the block index to manipulate the filters.

We will see the same output if we list filters for ingress qdisc of
ens7 and ens8, also for the block 22:

$ tc filter show block 22
filter block 22 protocol ip pref 25 flower chain 0
filter block 22 protocol ip pref 25 flower chain 0 handle 0x1
...

$ tc filter show dev ens7 ingress
filter block 22 protocol ip pref 25 flower chain 0
filter block 22 protocol ip pref 25 flower chain 0 handle 0x1
...

$ tc filter show dev ens8 ingress
filter block 22 protocol ip pref 25 flower chain 0
filter block 22 protocol ip pref 25 flower chain 0 handle 0x1
...

---
v10->v11:
- patch 2:
 - fixed error path when register_pernet_subsys fails pointed out by Cong
- patch 9:
 - rebased on top of the current net-next

v9->v10:
- patch 7:
 - fixed ifindex magic in the patch description
- userspace patches:
 - added manpages and patch descriptions

v8->v9:
- patch "net: sched: add rt netlink message type for block get" was
  removed, userspace check filter existence using qdisc dump

v7->v8:
- patch 7:
 - added comment to ifindex block magic
- patch 9:
 - new patch
- patch 10:
 - base this on the patch that introduces qdisc-generic block index
   attributes parsing/dumping
- patch 13:
 - rebased on top of current net-next

v6->v7:
- patch 1:
 - unsquashed shared block patch that was previously squashed by mistake
 - fixed error path in block create - freeing chain 0
- patch 2:
 - new patch - splitted from the previous one as it got accidentaly
   squashed in the rebasing process in the past
 - converted to idr extended
 - removed auto-generating of block indexes. Callers have to explicily
   tell that the block is shared by passing non-zero block index
 - fixed error path in block get ext - freeing chain 0
- patch 7:
 - changed extack message for block index handle as suggested by DaveA
 - added extack message when block index does not exist
 - the block ifindex magic is in define and change to 0xffffffff
   as suggested by Jamal
- patch 8:
 - new patch implementing RTM_GETBLOCK in order to query if the block
   with some index exists
- patch 9:
 - adjust to the core changes and check block index attributes for being 0

v5->v6:
- added patch 6 that introduces block handle

v4->v5:
- patch 5:
 - add tracking of binding of devs that are unable to offload and check
   that before block cbs call.

v3->v4:
- patch 1:
 - rebased on top of the current net-next
 - added some extack strings
- patch 3:
 - rebased on top of the current net-next
- patch 5:
 - propagate netdev_ops->ndo_setup_tc error up to tcf_block_offload_bind
   caller
- patch 7:
 - rebased on top of the current net-next

v2->v3:
- removed original patch 1, removing tp->q cls_bpf dependency. Fixed by
  Jakub in the meantime.
- patch 1:
 - rebased on top of the current net-next
- patch 5:
 - new patch
- patch 8:
 - removed "p_" prefix from block index function args
- patch 10:
 - add tc offload feature handling
====================

Acked-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>