From: "Matthieu Baerts (NGI0)" <matttbe@xxxxxxxxxx>
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@xxxxxxxxxxxxxxx
Suggested-by: Paolo Abeni <pabeni@xxxxxxxxxx>
Reviewed-by: Mat Martineau <martineau@xxxxxxxxxx>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@xxxxxxxxxx>
Link: https://patch.msgid.link/20240731-upstream-net-20240731-mptcp-endp-subflow-signal-v1-4-c8a9b036493b@xxxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
---
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++;
--
2.17.1
