Re: [PATCH mptcp-next v6 1/3] mptcp: pm: userspace: drop delete_local_addr helper

Hi Geliang,

On 27/06/2026 00:45, Geliang Tang wrote:
> From: Geliang Tang <[email protected]>
> 
> Address entries should not be removed from local_addr_list when a subflow
> is deleted by the userspace PM, should only be removed when sending a
> REMOVE_ADDR.
> 
> So mptcp_userspace_pm_delete_local_addr() helper shouldn't be called in
> mptcp_pm_nl_subflow_create_doit() and mptcp_pm_nl_subflow_destroy_doit().
> 
> Since this helper is open-coding in mptcp_pm_nl_remove_doit(), it can be
> dropped now.
> 
> Address entries are removed from local_addr_list when sending a REMOVE_ADDR
> by the userspace PM, the local_addr_used counter of PM should also be
> decremented accordingly.

I was re-reviewing this series after having read the comments from Sashiko:

https://sashiko.dev/#/patchset/[email protected]

I think the series is correct, but it feels like additional fixes are
required:

- msk->pm.userspace_pm_local_addr_list doesn't contain an entry for the
ID0 when initialised
  - That's probably fine, but then it means the ID0 case needs to be
handled separately, like it is with the in-kernel PM.
  - Or maybe easier to add it when the userspace PM is used, to avoid
all these exceptions?
    - If yes, then the remove_doit should no longer handle the ID0
differently as well.
    - same for announce_doit?
    - maybe better to do that to avoid all these exceptions?

- When creating a subflow with ID0, an entry can be added to the list
(to be checked)
  - If the ID0 is not added at init time, then an exception should be
added there
  - (also there is a check to avoid announcing ID0 → I think it is valid
to re-announce the ID0 if this address is no longer used, an exception
should be added there too, no?)

- each time the list is traversed, it doesn't take into account the ID0
case:
  - If the ID0 is not added at init time, then an extra check should be
added there

WDYT?

If yes, maybe this kind of patch can help? (not tested)

  https://github.com/matttbe/mptcp_net-next/commit/e03ee2728e98

Cheers,
Matt
-- 
Sponsored by the NGI0 Core fund.