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References: <20200506163033.3843-1-m-karicheri2@ti.com> <87r1vdkxes.fsf@intel.com>
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From:   Vladimir Oltean <olteanv@gmail.com>
Date:   Tue, 26 May 2020 00:37:56 +0300
Message-ID: <CA+h21hqiV71wc0v=-KkPbWNyXSY+-oiz+DsQLAe1XEJw7eP=_Q@mail.gmail.com>
Subject: Re: [net-next RFC PATCH 00/13] net: hsr: Add PRP driver
To:     Vinicius Costa Gomes <vinicius.gomes@intel.com>
Cc:     Murali Karicheri <m-karicheri2@ti.com>,
        "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>,
        netdev <netdev@vger.kernel.org>,
        lkml <linux-kernel@vger.kernel.org>, linux-api@vger.kernel.org,
        Sekhar Nori <nsekhar@ti.com>,
        Grygorii Strashko <grygorii.strashko@ti.com>
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Hi Vinicius,

On Thu, 21 May 2020 at 20:33, Vinicius Costa Gomes
<vinicius.gomes@intel.com> wrote:
>
> Murali Karicheri <m-karicheri2@ti.com> writes:
>
> > This RFC series add support for Parallel Redundancy Protocol (PRP)
> > as defined in IEC-62439-3 in the kernel networking subsystem. PRP
> > Uses a Redundancy Control Trailer (RCT) the format of which is
> > similar to HSR Tag. This is used for implementing redundancy.
> > RCT consists of 6 bytes similar to HSR tag and contain following
> > fields:-
> >
> > - 16-bit sequence number (SeqNr);
> > - 4-bit LAN identifier (LanId);
> > - 12 bit frame size (LSDUsize);
> > - 16-bit suffix (PRPsuffix).
> >
> > The PRPsuffix identifies PRP frames and distinguishes PRP frames
> > from other protocols that also append a trailer to their useful
> > data. The LSDUsize field allows the receiver to distinguish PRP
> > frames from random, nonredundant frames as an additional check.
> > LSDUsize is the size of the Ethernet payload inclusive of the
> > RCT. Sequence number along with LanId is used for duplicate
> > detection and discard.
> >
> > PRP node is also known as Dual Attached Node (DAN-P) since it
> > is typically attached to two different LAN for redundancy.
> > DAN-P duplicates each of L2 frames and send it over the two
> > Ethernet links. Each outgoing frame is appended with RCT.
> > Unlike HSR, these are added to the end of L2 frame and may be
> > treated as padding by bridges and therefore would be work with
> > traditional bridges or switches, where as HSR wouldn't as Tag
> > is prefixed to the Ethenet frame. At the remote end, these are
> > received and the duplicate frame is discarded before the stripped
> > frame is send up the networking stack. Like HSR, PRP also sends
> > periodic Supervision frames to the network. These frames are
> > received and MAC address from the SV frames are populated in a
> > database called Node Table. The above functions are grouped into
> > a block called Link Redundancy Entity (LRE) in the IEC spec.
> >
> > As there are many similarities between HSR and PRP protocols,
> > this patch re-use the code from HSR driver to implement PRP
> > driver. As many part of the code can be re-used, this patch
> > introduces a new common API definitions for both protocols and
> > propose to obsolete the existing HSR defines in
> > include/uapi/linux/if_link.h. New definitions are prefixed
> > with a HSR_PRP prefix. Similarly include/uapi/linux/hsr_netlink.h
> > is proposed to be replaced with include/uapi/linux/hsr_prp_netlink.h
> > which also uses the HSR_PRP prefix. The netlink socket interface
> > code is migrated (as well as the iproute2 being sent as a follow up
> > patch) to use the new API definitions. To re-use the code,
> > following are done as a preparatory patch before adding the PRP
> > functionality:-
> >
> >   - prefix all common code with hsr_prp
> >   - net/hsr -> renamed to net/hsr-prp
> >   - All common struct types, constants, functions renamed with
> >     hsr{HSR}_prp{PRP} prefix.
>
> I don't really like these prefixes, I am thinking of when support for
> IEEE 802.1CB is added, do we rename this to "hsr_prp_frer"?
>
> And it gets even more complicated, and using 802.1CB you can configure
> the tagging method and the stream identification function so a system
> can interoperate in a HSR or PRP network.
>

Is it a given that 802.1CB in Linux should be implemented using an hsr
upper device?
802.1CB is _much_ more flexible than both HSR and PRP. You can have
more than 2 ports, you can have per-stream rules (each stream has its
own sequence number), and those rules can identify the source, the
destination, or both the source and the destination.

> So, I see this as different methods of achieving the same result, which
> makes me think that the different "methods/types" (HSR and PRP in your
> case) should be basically different implementations of a "struct
> hsr_ops" interface. With this hsr_ops something like this:
>
>    struct hsr_ops {
>           int (*handle_frame)()
>           int (*add_port)()
>           int (*remove_port)()
>           int (*setup)()
>           void (*teardown)()
>    };
>
> >
> > Please review this and provide me feedback so that I can work to
> > incorporate them and send a formal patch series for this. As this
> > series impacts user space, I am not sure if this is the right
> > approach to introduce a new definitions and obsolete the old
> > API definitions for HSR. The current approach is choosen
> > to avoid redundant code in iproute2 and in the netlink driver
> > code (hsr_netlink.c). Other approach we discussed internally was
> > to Keep the HSR prefix in the user space and kernel code, but
> > live with the redundant code in the iproute2 and hsr netlink
> > code. Would like to hear from you what is the best way to add
> > this feature to networking core. If there is any other
> > alternative approach possible, I would like to hear about the
> > same.
>
> Why redudant code is needed in the netlink parts and in iproute2 when
> keeping the hsr prefix?
>
> >
> > The patch was tested using two TI AM57x IDK boards which are
> > connected back to back over two CPSW ports.
> >
> > Script used for creating the hsr/prp interface is given below
> > and uses the ip link command. Also provided logs from the tests
> > I have executed for your reference.
> >
> > iproute2 related patches will follow soon....
> >
> > Murali Karicheri
> > Texas Instruments
> >
> > ============ setup.sh =================================================
> > #!/bin/sh
> > if [ $# -lt 4 ]
> > then
> >        echo "setup-cpsw.sh <hsr/prp> <MAC-Address of slave-A>"
> >        echo "  <ip address for hsr/prp interface>"
> >        echo "  <if_name of hsr/prp interface>"
> >        exit
> > fi
> >
> > if [ "$1" != "hsr" ] && [ "$1" != "prp" ]
> > then
> >        echo "use hsr or prp as first argument"
> >        exit
> > fi
> >
> > if_a=eth2
> > if_b=eth3
> > if_name=$4
> >
> > ifconfig $if_a down
> > ifconfig $if_b down
> > ifconfig $if_a hw ether $2
> > ifconfig $if_b hw ether $2
> > ifconfig $if_a up
> > ifconfig $if_b up
> >
> > echo "Setting up $if_name with MAC address $2 for slaves and IP address $3"
> > echo "          using $if_a and $if_b"
> >
> > if [ "$1" = "hsr" ]; then
> >        options="version 1"
> > else
> >        options=""
> > fi
> >
> > ip link add name $if_name type $1 slave1 $if_a slave2 $if_b supervision 0 $options
> > ifconfig $if_name $3 up
> > ==================================================================================
> > PRP Logs:
> >
> > DUT-1 : https://pastebin.ubuntu.com/p/hhsRjTQpcr/
> > DUT-2 : https://pastebin.ubuntu.com/p/snPFKhnpk4/
> >
> > HSR Logs:
> >
> > DUT-1 : https://pastebin.ubuntu.com/p/FZPNc6Nwdm/
> > DUT-2 : https://pastebin.ubuntu.com/p/CtV4ZVS3Yd/
> >
> > Murali Karicheri (13):
> >   net: hsr: Re-use Kconfig option to support PRP
> >   net: hsr: rename hsr directory to hsr-prp to introduce PRP
> >   net: hsr: rename files to introduce PRP support
> >   net: hsr: rename hsr variable inside struct hsr_port to priv
> >   net: hsr: rename hsr_port_get_hsr() to hsr_prp_get_port()
> >   net: hsr: some renaming to introduce PRP driver support
> >   net: hsr: introduce common uapi include/definitions for HSR and PRP
> >   net: hsr: migrate HSR netlink socket code to use new common API
> >   net: hsr: move re-usable code for PRP to hsr_prp_netlink.c
> >   net: hsr: add netlink socket interface for PRP
> >   net: prp: add supervision frame generation and handling support
> >   net: prp: add packet handling support
> >   net: prp: enhance debugfs to display PRP specific info in node table
> >
> >  MAINTAINERS                                   |   2 +-
> >  include/uapi/linux/hsr_netlink.h              |   3 +
> >  include/uapi/linux/hsr_prp_netlink.h          |  50 ++
> >  include/uapi/linux/if_link.h                  |  19 +
> >  net/Kconfig                                   |   2 +-
> >  net/Makefile                                  |   2 +-
> >  net/hsr-prp/Kconfig                           |  37 ++
> >  net/hsr-prp/Makefile                          |  11 +
> >  net/hsr-prp/hsr_netlink.c                     | 202 +++++++
> >  net/{hsr => hsr-prp}/hsr_netlink.h            |  15 +-
> >  .../hsr_prp_debugfs.c}                        |  82 +--
> >  net/hsr-prp/hsr_prp_device.c                  | 562 ++++++++++++++++++
> >  net/hsr-prp/hsr_prp_device.h                  |  23 +
> >  net/hsr-prp/hsr_prp_forward.c                 | 558 +++++++++++++++++
> >  .../hsr_prp_forward.h}                        |  10 +-
> >  .../hsr_prp_framereg.c}                       | 323 +++++-----
> >  net/hsr-prp/hsr_prp_framereg.h                |  68 +++
> >  net/hsr-prp/hsr_prp_main.c                    | 194 ++++++
> >  net/hsr-prp/hsr_prp_main.h                    | 289 +++++++++
> >  net/hsr-prp/hsr_prp_netlink.c                 | 365 ++++++++++++
> >  net/hsr-prp/hsr_prp_netlink.h                 |  28 +
> >  net/hsr-prp/hsr_prp_slave.c                   | 222 +++++++
> >  net/hsr-prp/hsr_prp_slave.h                   |  37 ++
> >  net/hsr-prp/prp_netlink.c                     | 141 +++++
> >  net/hsr-prp/prp_netlink.h                     |  27 +
> >  net/hsr/Kconfig                               |  29 -
> >  net/hsr/Makefile                              |  10 -
> >  net/hsr/hsr_device.c                          | 509 ----------------
> >  net/hsr/hsr_device.h                          |  22 -
> >  net/hsr/hsr_forward.c                         | 379 ------------
> >  net/hsr/hsr_framereg.h                        |  62 --
> >  net/hsr/hsr_main.c                            | 154 -----
> >  net/hsr/hsr_main.h                            | 188 ------
> >  net/hsr/hsr_netlink.c                         | 514 ----------------
> >  net/hsr/hsr_slave.c                           | 198 ------
> >  net/hsr/hsr_slave.h                           |  33 -
> >  36 files changed, 3084 insertions(+), 2286 deletions(-)
> >  create mode 100644 include/uapi/linux/hsr_prp_netlink.h
> >  create mode 100644 net/hsr-prp/Kconfig
> >  create mode 100644 net/hsr-prp/Makefile
> >  create mode 100644 net/hsr-prp/hsr_netlink.c
> >  rename net/{hsr => hsr-prp}/hsr_netlink.h (58%)
> >  rename net/{hsr/hsr_debugfs.c => hsr-prp/hsr_prp_debugfs.c} (52%)
> >  create mode 100644 net/hsr-prp/hsr_prp_device.c
> >  create mode 100644 net/hsr-prp/hsr_prp_device.h
> >  create mode 100644 net/hsr-prp/hsr_prp_forward.c
> >  rename net/{hsr/hsr_forward.h => hsr-prp/hsr_prp_forward.h} (50%)
> >  rename net/{hsr/hsr_framereg.c => hsr-prp/hsr_prp_framereg.c} (56%)
> >  create mode 100644 net/hsr-prp/hsr_prp_framereg.h
> >  create mode 100644 net/hsr-prp/hsr_prp_main.c
> >  create mode 100644 net/hsr-prp/hsr_prp_main.h
> >  create mode 100644 net/hsr-prp/hsr_prp_netlink.c
> >  create mode 100644 net/hsr-prp/hsr_prp_netlink.h
> >  create mode 100644 net/hsr-prp/hsr_prp_slave.c
> >  create mode 100644 net/hsr-prp/hsr_prp_slave.h
> >  create mode 100644 net/hsr-prp/prp_netlink.c
> >  create mode 100644 net/hsr-prp/prp_netlink.h
> >  delete mode 100644 net/hsr/Kconfig
> >  delete mode 100644 net/hsr/Makefile
> >  delete mode 100644 net/hsr/hsr_device.c
> >  delete mode 100644 net/hsr/hsr_device.h
> >  delete mode 100644 net/hsr/hsr_forward.c
> >  delete mode 100644 net/hsr/hsr_framereg.h
> >  delete mode 100644 net/hsr/hsr_main.c
> >  delete mode 100644 net/hsr/hsr_main.h
> >  delete mode 100644 net/hsr/hsr_netlink.c
> >  delete mode 100644 net/hsr/hsr_slave.c
> >  delete mode 100644 net/hsr/hsr_slave.h
> >
> > --
> > 2.17.1
> >
>
> --
> Vinicius

Thanks,
-Vladimir