Re: [PATCH v3 iproute2-next] ip link: add sub-command to view and change DSA conduit interface

On 9/22/22 4:06 PM, Vladimir Oltean wrote:

Support the "dsa" kind of rtnl_link_ops exported by the kernel, and
export reads/writes to IFLA_DSA_MASTER.

Examples:

$ ip link set swp0 type dsa conduit eth1

$ ip -d link show dev swp0
    (...)
    dsa conduit eth0

$ ip -d -j link show swp0
[
	{
		"link": "eth1",
		"linkinfo": {
			"info_kind": "dsa",
			"info_data": {
				"conduit": "eth1"
			}
		},
	}
]

Note that by construction and as shown in the example, the IFLA_LINK
reported by a DSA user port is identical to what is reported through
IFLA_DSA_MASTER. However IFLA_LINK is not writable, and overloading its
meaning to make it writable would clash with other users of IFLA_LINK
(vlan etc) for which writing this property does not make sense.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
---
v1->v2:
- update man page
v2->v3:
- update main ip-link help text to print the new 'dsa' link type
- rename the 'master' keyword to 'conduit' and keep 'master' as a
  fallback
- to avoid using the 'DSA master' term in the man page, stop explaining
  which interfaces are eligible for this operation, and just refer to
  the kernel documentation. Note that since the support was added in
  net-next, the htmldocs have not been regenerated yet.

 include/uapi/linux/if_link.h | 10 ++++++
 ip/Makefile                  |  2 +-
 ip/iplink.c                  |  2 +-
 ip/iplink_dsa.c              | 68 ++++++++++++++++++++++++++++++++++++
 man/man8/ip-link.8.in        | 35 +++++++++++++++++++
 5 files changed, 115 insertions(+), 2 deletions(-)
 create mode 100644 ip/iplink_dsa.c

LGTM.