From: "Matthieu Baerts (NGI0)" matttbe@kernel.org

It sounds better to avoid wasting cycles and / or put extreme memory pressure on the system by trying to create new subflows if it was not possible to add a new item in the announce list.

While at it, a warning is now printed if the entry was already in the list as it should not happen with the in-kernel path-manager. With this PM, mptcp_pm_alloc_anno_list() should only fail in case of memory pressure.

Fixes: b6c08380860b ("mptcp: remove addr and subflow in PM netlink") Cc: stable@vger.kernel.org Suggested-by: Paolo Abeni pabeni@redhat.com Reviewed-by: Mat Martineau martineau@kernel.org Signed-off-by: Matthieu Baerts (NGI0) matttbe@kernel.org Link: https://patch.msgid.link/20240731-upstream-net-20240731-mptcp-endp-subflow-s... Signed-off-by: Jakub Kicinski kuba@kernel.org --- net/mptcp/pm_netlink.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/net/mptcp/pm_netlink.c b/net/mptcp/pm_netlink.c index 780f4cca165c..2be7af377cda 100644 --- a/net/mptcp/pm_netlink.c +++ b/net/mptcp/pm_netlink.c @@ -348,7 +348,7 @@ bool mptcp_pm_alloc_anno_list(struct mptcp_sock *msk, add_entry = mptcp_lookup_anno_list_by_saddr(msk, addr);

if (add_entry) { - if (mptcp_pm_is_kernel(msk)) + if (WARN_ON_ONCE(mptcp_pm_is_kernel(msk))) return false;

sk_reset_timer(sk, &add_entry->add_timer, @@ -555,8 +555,6 @@ static void mptcp_pm_create_subflow_or_signal_addr(struct mptcp_sock *msk)

/* check first for announce */ if (msk->pm.add_addr_signaled < add_addr_signal_max) { - local = select_signal_address(pernet, msk); - /* due to racing events on both ends we can reach here while * previous add address is still running: if we invoke now * mptcp_pm_announce_addr(), that will fail and the @@ -567,11 +565,15 @@ static void mptcp_pm_create_subflow_or_signal_addr(struct mptcp_sock *msk) if (msk->pm.addr_signal & BIT(MPTCP_ADD_ADDR_SIGNAL)) return;

+ local = select_signal_address(pernet, msk); if (!local) goto subflow;

+ /* If the alloc fails, we are on memory pressure, not worth + * continuing, and trying to create subflows. + */ if (!mptcp_pm_alloc_anno_list(msk, &local->addr)) - goto subflow; + return;

__clear_bit(local->addr.id, msk->pm.id_avail_bitmap); msk->pm.add_addr_signaled++;