mptcp: pm: re-using ID of unused flushed subflows

commit ef34a6ea upstream.

If no subflows are attached to the 'subflow' endpoints that are being
flushed, the corresponding addr IDs will not be marked as available
again.

Mark all ID as being available when flushing all the 'subflow'
endpoints, and reset local_addr_used counter to cover these cases.

Note that mptcp_pm_remove_addrs_and_subflows() helper is only called for
flushing operations, not to remove a specific set of addresses and
subflows.

Fixes: 06faa227 ("mptcp: remove multi addresses and subflows in PM")
Cc: stable@vger.kernel.org
Reviewed-by: Mat Martineau <martineau@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20240819-net-mptcp-pm-reusing-id-v1-5-38035d40de5b@kernel.org


Signed-off-by: Jakub Kicinski <kuba@kernel.org>
[ No conflicts, but the line modifying msk->pm.id_avail_bitmap has been
  removed, as it is not in this version, introduced later in commit
  86e39e04 ("mptcp: keep track of local endpoint still available for
  each msk") and depending on other ones. The best we can do in this
  version is to reset local_addr_used counter, better than nothing. ]
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>