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SubjectRe: [RFC PATCH net-next v3 00/21] ethtool netlink interface, part 1
Mon, Feb 18, 2019 at 07:21:24PM CET, mkubecek@suse.cz wrote:
>Note: this is marked as RFC because it's rather late in the cycle; the plan
>is to make a regular submission (with changes based on review) once
>net-next reopens after the 5.1 merge window. The full (work in progress)
>series, together with the (userspace) ethtool counterpart can be found at
>https://github.com/mkubecek/ethnl
>
>This is first part of alternative userspace interface for ethtool. The aim
>is to address some long known issues with the ioctl interface, mainly lack
>of extensibility, raciness, limited error reporting and absence of
>notifications.
>
>The interface uses generic netlink family "ethtool"; it provides multicast
>group "monitor" which is used for notifications. Documentation for the
>interface is in Documentation/networking/ethtool-netlink.txt
>
>Basic concepts:
>
>- the goal is to provide all features of ioctl interface but allow
> easier future extensions; at some point, it should be possible to have
> full ethtool functionality without using the ioctl interface

I'm not sure it is a good idea to map the existing iface to netlink
fully. There are things in ethtool which are not really unique for
Ethernet. Those things should be put somewhere else.


>- inextensibility of ioctl interface resulted in way too many commands,
> many of them obsoleted by newer ones; reduce the number by ignoring the
> obsolete commands and grouping some together
>- for "set" type commands, allows passing only the attributes to be
> changed; therefore we don't need a get-modify-set cycle (which is
> inherently racy), userspace can simply say what it wants to change
>- provide notifications to multicast group "monitor" like rtnetlink does,
> i.e. in the form of messages close to replies to "get" requests
>- allow dump requests to get some information about all network devices
> providing it
>- be less dependent on ethtool and kernel being in sync; allow e.g. saying
> "ethtool -s eth0 advertise foo off" without ethtool knowing what "foo"
> means; it's kernel's job to know what mode "xyz" is and if it exists and
> is supported
>
>Main changes between RFC v2 and RFC v3:
>
>- do not allow building as a module (no netdev notifiers needed)
>- drop some obsolete fields
>- add permanent hw address, timestamping and private flags support
>- rework bitset handling to get rid of variable length arrays
>- notify monitor on device renames
>- restructure GET_SETTINGS/SET_SETTINGS messages
>- split too long patches and submit only first part of the series
>
>Main changes between RFC v1 and RFC v2:
>
>- support dumps for all "get" requests
>- provide notifications for changes related to supported request types
>- support getting string sets (both global and per device)
>- support getting/setting device features
>- get rid of family specific header, everything passed as attributes
>- split netlink code into multiple files in net/ethtool/ directory
>
>ToDo / open questions:
>
>- some features provided by ethtool would rather belong to devlink (and
> some are already superseded by devlink); however, only few drivers
> provide devlink interface at the moment and as recent discussion on
> flashing revealed, we cannot rely on devlink's presence

Could you explain why please?


>
>- while the netlink interface allows easy future extensions, ethtool_ops
> interface does not; some settings could be implemented using tunables and
> accessed via relevant netlink messages (as well as tunables) from
> userspace but in the long term, something better will be needed
>
>- currently, all communication with drivers via ethtool_ops is done
> under RTNL as this is what ioctl interface does and likely many
> ethtool_ops handlers rely on that; if we are going to rework ethtool_ops
> in the future ("phase two"), it would be nice to get rid of it
>
>- ethtool_ops should pass extack pointer to allow drivers more meaningful
> error reporting; it's not clear, however, how to pass information about
> offending attribute
>
>- notifications are sent whenever a change is done via netlink API or
> ioctl API and for netdev features also whenever they are updated using
> netdev_change_features(); it would be desirable to notify also about
> link state and negotiation result (speed/duplex and partner link
> modes) but it would be more tricky
>
>Michal Kubecek (21):
> netlink: introduce nla_put_bitfield32()
> ethtool: move to its own directory
> ethtool: introduce ethtool netlink interface
> ethtool: helper functions for netlink interface
> ethtool: netlink bitset handling
> ethtool: support for netlink notifications
> ethtool: implement EVENT notifications
> ethtool: generic handlers for GET requests
> ethtool: move string arrays into common file
> ethtool: provide string sets with GET_STRSET request
> ethtool: provide driver/device information in GET_INFO request
> ethtool: provide permanent hardware address in GET_INFO request
> ethtool: provide timestamping information in GET_INFO request
> ethtool: provide link mode names as a string set
> ethtool: provide link settings and link modes in GET_SETTINGS request
> ethtool: provide WoL information in GET_SETTINGS request
> ethtool: provide message level in GET_SETTINGS request
> ethtool: provide link state in GET_SETTINGS request
> ethtool: provide device features in GET_SETTINGS request
> ethtool: provide private flags in GET_SETTINGS request
> ethtool: send netlink notifications about setting changes
>
> Documentation/networking/ethtool-netlink.txt | 441 +++++++++++++
> include/linux/ethtool_netlink.h | 17 +
> include/linux/netdevice.h | 14 +
> include/net/netlink.h | 15 +
> include/uapi/linux/ethtool.h | 10 +
> include/uapi/linux/ethtool_netlink.h | 265 ++++++++
> include/uapi/linux/net_tstamp.h | 13 +
> net/Kconfig | 8 +
> net/Makefile | 2 +-
> net/core/Makefile | 2 +-
> net/ethtool/Makefile | 7 +
> net/ethtool/bitset.c | 572 +++++++++++++++++
> net/ethtool/bitset.h | 40 ++
> net/ethtool/common.c | 227 +++++++
> net/ethtool/common.h | 29 +
> net/ethtool/info.c | 332 ++++++++++
> net/{core/ethtool.c => ethtool/ioctl.c} | 244 ++-----
> net/ethtool/netlink.c | 634 +++++++++++++++++++
> net/ethtool/netlink.h | 252 ++++++++
> net/ethtool/settings.c | 559 ++++++++++++++++
> net/ethtool/strset.c | 461 ++++++++++++++
> 21 files changed, 3937 insertions(+), 207 deletions(-)
> create mode 100644 Documentation/networking/ethtool-netlink.txt
> create mode 100644 include/linux/ethtool_netlink.h
> create mode 100644 include/uapi/linux/ethtool_netlink.h
> create mode 100644 net/ethtool/Makefile
> create mode 100644 net/ethtool/bitset.c
> create mode 100644 net/ethtool/bitset.h
> create mode 100644 net/ethtool/common.c
> create mode 100644 net/ethtool/common.h
> create mode 100644 net/ethtool/info.c
> rename net/{core/ethtool.c => ethtool/ioctl.c} (91%)
> create mode 100644 net/ethtool/netlink.c
> create mode 100644 net/ethtool/netlink.h
> create mode 100644 net/ethtool/settings.c
> create mode 100644 net/ethtool/strset.c
>
>--
>2.20.1
>

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