On 09/01/2020 17:06, Horatiu Vultur wrote: > Media Redundancy Protocol is a data network protocol standardized by > International Electrotechnical Commission as IEC 62439-2. It allows rings of > Ethernet switches to overcome any single failure with recovery time faster than > STP. It is primarily used in Industrial Ethernet applications. > > This is the first proposal of implementing a subset of the standard. It supports > only 2 roles of an MRP node. It supports only Media Redundancy Manager(MRM) and > Media Redundancy Client(MRC). In a MRP ring, each node needs to support MRP and > in a ring can be only one MRM and multiple MRC. It is possible to have multiple > instances of MRP on a single node. But a port can be part of only one MRP > instance. > > The MRM is responsible for detecting when there is a loop in the ring. It is > sending the frame MRP_Test to detect the loops. It would send MRP_Test on both > ports in the ring and if the frame is received at the other end, then the ring > is closed. Meaning that there is a loop. In this case it sets the port state to > BLOCKED, not allowing traffic to pass through except MRP frames. In case it > stops receiving MRP_Test frames from itself then the MRM will detect that the > ring is open, therefor it would notify the other nodes of this change and will > set the state of the port to be FORWARDING. > > The MRC is responsible for forwarding MRP_Test frames between the ring ports > (and not to flood on other ports) and to listen when there is a change in the > network to clear the FDB. > > Similar with STP, MRP is implemented on top of the bridge and they can't be > enable at the same time. While STP runs on all ports of the bridge, MRP needs to > run only on 2 ports. > > The bridge needs to: > - notify when the link of one of the ports goes down or up, because MRP instance > needs to react to link changes by sending MRP_LinkChange frames. > - notify when one of the ports are removed from the bridge or when the bridge > is destroyed, because if the port is part of the MRP ring then MRP state > machine should be stopped. > - add a handler to allow MRP instance to process MRP frames, if MRP is enabled. > This is similar with STP design. > - add logic for MRP frames inside the bridge. The bridge will just detect MRP > frames and it would forward them to the upper layer to allow to process it. > - update the logic to update non-MRP frames. If MRP is enabled, then look also > at the state of the port to decide to forward or not. > > To create a MRP instance on the bridge: > $ bridge mrp add dev br0 p_port eth0 s_port eth1 ring_role 2 ring_id 1 > > Where: > p_port, s_port: can be any port under the bridge > ring_role: can have the value 1(MRC - Media Redundancy Client) or > 2(MRM - Media Redundancy Manager). In a ring can be only one MRM. > ring_id: unique id for each MRP instance. > > It is possible to create multiple instances. Each instance has to have it's own > ring_id and a port can't be part of multiple instances: > $ bridge mrp add dev br0 p_port eth2 s_port eth3 ring_role 1 ring_id 2 > > To see current MRP instances and their status: > $ bridge mrp show > dev br0 p_port eth2 s_port eth3 ring_role 1 ring_id 2 ring_state 3 > dev br0 p_port eth0 s_port eth1 ring_role 2 ring_id 1 ring_state 4 > > If this patch series is well received, the in the future it could be extended > with the following: > - add support for Media Redundancy Automanager. This role allows a node to > detect if needs to behave as a MRM or MRC. The advantage of this role is that > the user doesn't need to configure the nodes each time they are added/removed > from a ring and it adds redundancy to the manager. > - add support for Interconnect rings. This allow to connect multiple rings. > - add HW offloading. The standard defines 4 recovery times (500, 200, 30 and 10 > ms). To be able to achieve 30 and 10 it is required by the HW to generate the > MRP_Test frames and detect when the ring is open/closed. > > Horatiu Vultur (3): > net: bridge: mrp: Add support for Media Redundancy Protocol > net: bridge: mrp: Integrate MRP into the bridge > net: bridge: mrp: Add netlink support to configure MRP > > include/uapi/linux/if_bridge.h | 27 + > include/uapi/linux/if_ether.h | 1 + > include/uapi/linux/rtnetlink.h | 7 + > net/bridge/Kconfig | 12 + > net/bridge/Makefile | 2 + > net/bridge/br.c | 19 + > net/bridge/br_device.c | 3 + > net/bridge/br_forward.c | 1 + > net/bridge/br_if.c | 10 + > net/bridge/br_input.c | 22 + > net/bridge/br_mrp.c | 1517 ++++++++++++++++++++++++++++++++ > net/bridge/br_mrp_timer.c | 227 +++++ > net/bridge/br_netlink.c | 9 + > net/bridge/br_private.h | 30 + > net/bridge/br_private_mrp.h | 208 +++++ > security/selinux/nlmsgtab.c | 5 +- > 16 files changed, 2099 insertions(+), 1 deletion(-) > create mode 100644 net/bridge/br_mrp.c > create mode 100644 net/bridge/br_mrp_timer.c > create mode 100644 net/bridge/br_private_mrp.h > Hi all, I agree with Stephen here, IMO you have to take note of how STP has progressed and that bringing it in the kernel was a mistake, these days mstpd has an active community and much better support which is being extended. This looks best implemented in user-space in my opinion with minimal kernel changes to support it. You could simply open a packet socket with a filter and work through that, you don't need new netlink sockets. I'm not familiar with the protocol so can't really be the judge of that, if you present a good argument for needing a new netlink socket for these packets - then sure, ok. If you do decide to continue with the kernel version (which I would again discourage) a few general points (from a quick scan): - the single 1.6+k line patch is just hard to review, please break it into more digestable and logical pieces - the locking is wrong, also there're a few use-after-free bugs - please re-work the bridge integration code, it can be simplified and tests can be eliminated - your netlink helpers usage is generally wrong and needs more work - use the already existing port states instead of adding new ones and you can avoid some tests in fast-path - perhaps look into using br_afspec() for configuration/retrieval initially ? I don't think you need the new rtm messages yet. - I'm sure I can go on, but I really think all of this should be put in user-space - in-kernel STP is a great example of how _not_ to do it. :) As a bonus you'll avoid 90% of the problems above just by making your own abstractions and using them for it. Thanks, Nik
