[PATCH] ipv6: create ra_mtu proc file to only record mtu in RA

[David Ahern]

On 6/1/21 3:16 AM, Rocco Yue wrote:
> For this patch set, if RA message carries the mtu option,
> "proc/sys/net/ipv6/conf/<iface>/ra_mtu" will be updated to the
> mtu value carried in the last RA message received, and ra_mtu
> is an independent proc file, which is not affected by the update
> of interface mtu value.

I am not a fan of more /proc/sys files.

You are adding it to devconf which is good. You can add another link
attribute, e.g., IFLA_RA_MTU, and have it returned on link queries.

Make sure the attribute can not be sent in a NEWLINK or SETLINK request;
it should be read-only for GETLINK.