Re: [PATCH 1/1] Network: support default route metric per interface

[David Ahern <dsahern@gmail.com>]

On 9/25/20 5:11 PM, Qingtao Cao wrote:
> From: Qingtao Cao <qingtao.cao@digi.com>
> 
> Add /proc/sys/net/ipv[4|6]/conf/<device>/def_rt_metric sysfs attribute
> file for each network interface so that userspace programs can specify
> different default route metrics for each interface, which will also be
> applied by the kernel when new routes are automatically created for
> relevant interfaces, when userspace programs may have not specified
> metrics via relevant netlink messages for example.
> 
> Signed-off-by: Qingtao Cao <qingtao.cao@digi.com>
> Signed-off-by: David Leonard <david.leonard@digi.com>
> ---
>  Documentation/networking/ip-sysctl.rst |  8 +++++
>  include/linux/inetdevice.h             |  4 +++
>  include/linux/ipv6.h                   |  3 ++
>  include/net/ip6_route.h                | 15 ++++++++
>  include/uapi/linux/ip.h                |  1 +
>  include/uapi/linux/ipv6.h              |  1 +
>  net/ipv4/Kconfig                       | 13 +++++++
>  net/ipv4/devinet.c                     |  3 ++
>  net/ipv4/fib_frontend.c                | 27 ++++++++++++++
>  net/ipv6/addrconf.c                    | 30 ++++++++++++++--
>  net/ipv6/route.c                       | 50 ++++++++++++++++++++++++--
>  11 files changed, 150 insertions(+), 5 deletions(-)

uh, no.

The metric can be specified for prefix routes via IFA_RT_PRIORITY. There
is no reason for bloating the code and adding another sys knob for this.
Fix your network manager to set the priority when the address is created.