netdev - Re: [PATCH net-next v2] net: add sysctl to disable rfc4862 5.5.3e lifetime handling

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Date: Wed, 13 Sep 2023 10:20:39 -0700
From: Maciej Żenczykowski <maze@...gle.com>
To: Lorenzo Colitti <lorenzo@...gle.com>
Cc: Jiri Pirko <jiri@...nulli.us>, Patrick Rohr <prohr@...gle.com>, 
	"David S. Miller" <davem@...emloft.net>, 
	Linux Network Development Mailing List <netdev@...r.kernel.org>, Jen Linkova <furry@...gle.com>
Subject: Re: [PATCH net-next v2] net: add sysctl to disable rfc4862 5.5.3e
 lifetime handling

On Wed, Sep 13, 2023 at 1:50 AM Lorenzo Colitti <lorenzo@...gle.com> wrote:
> On Wed, Sep 13, 2023 at 5:12 PM Jiri Pirko <jiri@...nulli.us> wrote:
> > >+      - If enabled, RFC4862 section 5.5.3e is used to determine
> > >+        the valid lifetime of the address.
> > >+      - If disabled, the PIO valid lifetime will always be honored.
> >
> > Can't you reverse the logic and call it something like:
> > ra_honor_pio_lifetime
>
> Maybe accept_ra_pinfo_low_lifetime ? Consistent with the existing
> accept_ra_pinfo which controls whether PIOs are accepted.

accept_ra... is about whether to accept or drop/ignore an RA or
portion there-of.
We considered it and decided it was inappropriate here, as this new
sysctl doesn't change drop/ignore.

As such it should be named ra_...

ra_honor_pio_lifetime or ra_honor_pio_lft has the problem of seeming
to be a lifetime (ie. seconds) and not a boolean,
but does look much better...  (maybe using _lifetime instead of _lft
makes it sufficiently different from the existing _lft sysctls that it
being a boolean is ok?)

...or... perhaps we do actually make it an actual number of seconds,

ra_pio_min_valid_lft, and we default it to MIN_VALID_LIFETIME,
then I believe a value of 0 would get the desired behaviour...