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[libteam] Support multiple ports with LACP fallback
Fixes #7555 and #8866. While the LACP fallback HLD correctly describes the behavior for LAGs with multiple ports, the actual implementation only worked for single-port LAGs. When multiple ports are present, the fallback mode would select all ports, therefore making it useless for the purpose described in the HLD (PXE-booting). Therefore, this commit adds a patch to implement the desired behavior: If all non-disabled ports are defaulted, *one* port goes into fallback mode and gets selected for the LAG. As soon as any port receives a LACPDU, the fallback port goes back to defaulted. The fallback port is selected by higher port priority or, if both have equal priority (the default), by lower port number (as described in the HLD). Signed-off-by: Lukas Stockner <[email protected]>
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‎src/libteam/patch/0017-Extend-LACP-fallback-support-to-multiple-ports.patch

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From 95f2377a851b6ab49ab8042b239b67dfa20ec9d8 Mon Sep 17 00:00:00 2001
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From: Lukas Stockner <[email protected]>
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Date: Fri, 13 May 2022 02:32:37 +0200
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Subject: [PATCH] Extend LACP fallback support to multiple ports
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---
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teamd/teamd_runner_lacp.c | 127 ++++++++++++++++++++++++++++++++------
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utils/teamdctl.c | 7 ++-
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2 files changed, 113 insertions(+), 21 deletions(-)
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diff --git a/teamd/teamd_runner_lacp.c b/teamd/teamd_runner_lacp.c
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index 1e5478b..e6676df 100644
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--- a/teamd/teamd_runner_lacp.c
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+++ b/teamd/teamd_runner_lacp.c
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@@ -213,6 +213,7 @@ enum lacp_port_state {
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PORT_STATE_CURRENT = 1,
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PORT_STATE_EXPIRED = 2,
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PORT_STATE_DEFAULTED = 3,
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+ PORT_STATE_FALLBACK = 4,
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};
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static const char *lacp_port_state_name[] = {
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@@ -220,6 +221,7 @@ static const char *lacp_port_state_name[] = {
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"current",
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"expired",
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"defaulted",
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+ "fallback",
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};
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struct lacp_port {
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@@ -590,24 +592,10 @@ static bool lacp_port_loopback_free(struct lacp_port *lacp_port)
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return true;
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}
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-/*
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- * is_lacp_fallback_eligible - is lacp_port eligible to go into lacp fallback mode
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- *
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- * Return true if it is, false otherwise
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- */
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-static bool is_lacp_fallback_eligible(struct lacp_port *lacp_port)
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-{
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- teamd_log_dbg(lacp_port->ctx, "%s fallback eligible state \"%d \" cfg \"%d\".",
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- lacp_port->tdport->ifname, lacp_port->state,
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- lacp_port->lacp->cfg.fallback);
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- return lacp_port->state == PORT_STATE_DEFAULTED &&
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- lacp_port->lacp->cfg.fallback;
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-}
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-
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static bool lacp_port_selectable_state(struct lacp_port *lacp_port)
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{
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if (lacp_port->state == PORT_STATE_CURRENT ||
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- is_lacp_fallback_eligible(lacp_port))
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+ lacp_port->state == PORT_STATE_FALLBACK)
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return true;
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return false;
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}
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@@ -616,7 +604,7 @@ static bool lacp_port_unselectable_state(struct lacp_port *lacp_port)
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{
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if (lacp_port->state == PORT_STATE_CURRENT ||
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lacp_port->state == PORT_STATE_EXPIRED ||
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- is_lacp_fallback_eligible(lacp_port))
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+ lacp_port->state == PORT_STATE_FALLBACK)
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return false;
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return true;
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}
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@@ -633,7 +621,7 @@ static int lacp_port_should_be_enabled(struct lacp_port *lacp_port)
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if (lacp_port_selected(lacp_port) &&
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lacp_port->agg_lead == lacp->selected_agg_lead &&
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(lacp_port->partner.state & INFO_STATE_SYNCHRONIZATION ||
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- is_lacp_fallback_eligible(lacp_port)))
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+ lacp_port->state == PORT_STATE_FALLBACK))
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return true;
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return false;
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}
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@@ -645,7 +633,7 @@ static int lacp_port_should_be_disabled(struct lacp_port *lacp_port)
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if (!lacp_port_selected(lacp_port) ||
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lacp_port->agg_lead != lacp->selected_agg_lead ||
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(!(lacp_port->partner.state & INFO_STATE_SYNCHRONIZATION) &&
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- !is_lacp_fallback_eligible(lacp_port)))
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+ lacp_port->state != PORT_STATE_FALLBACK))
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return true;
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return false;
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}
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@@ -1313,7 +1301,7 @@ static void lacp_port_actor_update(struct lacp_port *lacp_port)
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}
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if (lacp_port->state == PORT_STATE_EXPIRED)
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state |= INFO_STATE_EXPIRED;
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- if (lacp_port->state == PORT_STATE_DEFAULTED)
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+ if (lacp_port->state == PORT_STATE_DEFAULTED || lacp_port->state == PORT_STATE_FALLBACK)
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state |= INFO_STATE_DEFAULTED;
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if (teamd_port_count(lacp_port->ctx) > 0)
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state |= INFO_STATE_AGGREGATION;
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@@ -1322,6 +1310,101 @@ static void lacp_port_actor_update(struct lacp_port *lacp_port)
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static int lacpdu_send(struct lacp_port *lacp_port);
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+static int lacp_port_set_state(struct lacp_port *lacp_port,
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+ enum lacp_port_state new_state);
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+
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+static bool lacp_port_better_for_fallback(struct lacp_port *lacp_port1, struct lacp_port *lacp_port2)
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+{
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+ int system_diff;
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+ struct lacpdu_info *actor1;
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+ struct lacpdu_info *actor2;
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+
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+ if (!lacp_port2)
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+ return true;
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+
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+ actor1 = &lacp_port1->actor;
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+ actor2 = &lacp_port2->actor;
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+
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+ system_diff = memcmp(actor1->system, actor2->system, ETH_ALEN);
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+ /* If system MACs differ, the port with the lower system wins. */
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+ if (system_diff != 0)
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+ return system_diff < 0;
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+
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+ /* If port priorities differ, the port with the higher priority wins. */
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+ if (actor2->port_priority != actor1->port_priority)
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+ return (ntohs(actor1->port_priority) > ntohs(actor2->port_priority));
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+
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+ /* Otherwise, the port with the lower number wins. */
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+ return ntohs(actor1->port) < ntohs(actor2->port);
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+}
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+
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+static int lacp_ports_update_fallback_state(struct lacp *lacp)
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+{
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+ struct lacp_port *current_fallback = NULL;
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+ struct lacp_port *new_fallback = NULL;
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+ struct teamd_port *tdport;
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+ bool do_fallback = true;
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+
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+ /* If fallback is disabled, no need to do anything. */
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+ if (!lacp->cfg.fallback) {
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+ return 0;
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+ }
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+
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+ /* Check all ports.
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+ * If any port is receiving LACPDUs, we disable fallback altogether.
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+ * Otherwise, the non-disabled port with the highest priority is moved
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+ * to fallback mode. */
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+ teamd_for_each_tdport(tdport, lacp->ctx) {
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+ struct lacp_port *lacp_port = lacp_port_get(lacp, tdport);
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+
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+ if (lacp_port->state == PORT_STATE_DISABLED) {
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+ /* Ignore disabled ports. */
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+ continue;
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+ }
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+ if (lacp_port->state == PORT_STATE_CURRENT || lacp_port->state == PORT_STATE_EXPIRED) {
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+ /* If at least one port is currently receiving LACPDUs, don't do any fallback. */
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+ do_fallback = false;
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+ continue;
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+ }
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+ if (lacp_port->state == PORT_STATE_FALLBACK) {
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+ /* Remember what the current fallback port is. */
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+ current_fallback = lacp_port;
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+ }
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+
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+ /* Port is either defaulted or already fallback, so it's a candidate for new fallback port.
159+
+ * If there is already a viable candidate, check which one has higher priority. */
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+ if (lacp_port_better_for_fallback(lacp_port, new_fallback)) {
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+ new_fallback = lacp_port;
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+ }
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+ }
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+
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+ if (!do_fallback) {
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+ new_fallback = NULL;
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+ }
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+
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+ if (current_fallback == new_fallback) {
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+ /* Current state is already fine, nothing to do. */
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+ return 0;
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+ }
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+
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+ /* Fallback port has changed, move the old one back to defaulted (if there was one)
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+ * and move the new one to fallback (if there is one)
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+ */
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+ if (current_fallback) {
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+ /* Note: lacp_port_set_state will call back into lacp_ports_update_fallback_state.
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+ * This is fine though: We disable the old fallback, so the second time will find
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+ * that there is no fallback and enable the new one.
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+ * Therefore, after this call, we don't need to set the state of new_fallback here
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+ * as well.*/
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+ return lacp_port_set_state(current_fallback, PORT_STATE_DEFAULTED);
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+ }
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+ else if (new_fallback) {
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+ return lacp_port_set_state(new_fallback, PORT_STATE_FALLBACK);
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+ }
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+
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+ return 0;
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+}
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+
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static int lacp_port_set_state(struct lacp_port *lacp_port,
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enum lacp_port_state new_state)
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{
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@@ -1361,6 +1444,7 @@ static int lacp_port_set_state(struct lacp_port *lacp_port,
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LACP_TIMEOUT_CB_NAME, lacp_port);
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break;
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case PORT_STATE_DEFAULTED:
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+ case PORT_STATE_FALLBACK:
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teamd_loop_callback_disable(lacp_port->ctx,
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LACP_TIMEOUT_CB_NAME, lacp_port);
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memset(&lacp_port->partner, 0, sizeof(lacp_port->partner));
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@@ -1394,6 +1478,10 @@ static int lacp_port_set_state(struct lacp_port *lacp_port,
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if (err)
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return err;
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+ err = lacp_ports_update_fallback_state(lacp_port->lacp);
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+ if (err)
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+ return err;
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+
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lacp_port_actor_update(lacp_port);
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return lacpdu_send(lacp_port);
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@@ -1649,6 +1737,7 @@ static int lacp_callback_timeout(struct teamd_context *ctx, int events,
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err = lacp_port_set_state(lacp_port, PORT_STATE_DEFAULTED);
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break;
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case PORT_STATE_DEFAULTED:
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+ case PORT_STATE_FALLBACK:
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case PORT_STATE_DISABLED:
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/* This can't happen */
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break;
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diff --git a/utils/teamdctl.c b/utils/teamdctl.c
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index 7fcbfff..d8c71c1 100644
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--- a/utils/teamdctl.c
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+++ b/utils/teamdctl.c
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@@ -502,12 +502,14 @@ static int stateview_json_runner_process(char *runner_name, json_t *json)
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int active;
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int sys_prio;
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int fast_rate;
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+ int fallback;
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pr_out("runner:\n");
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- err = json_unpack(json, "{s:{s:b, s:i, s:b}}", "runner",
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+ err = json_unpack(json, "{s:{s:b, s:i, s:b, s:b}}", "runner",
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"active", &active,
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"sys_prio", &sys_prio,
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- "fast_rate", &fast_rate);
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+ "fast_rate", &fast_rate,
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+ "fallback", &fallback);
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if (err) {
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pr_err("Failed to parse JSON runner dump.\n");
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return -EINVAL;
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@@ -515,6 +517,7 @@ static int stateview_json_runner_process(char *runner_name, json_t *json)
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pr_out_indent_inc();
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pr_out("active: %s\n", boolyesno(active));
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pr_out("fast rate: %s\n", boolyesno(fast_rate));
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+ pr_out("fallback: %s\n", boolyesno(fallback));
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pr_out2("system priority: %d\n", sys_prio);
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pr_out_indent_dec();
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}
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--
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2.41.0
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‎src/libteam/patch/series

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@@ -14,3 +14,4 @@
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0014-dont-move-the-port-state-from-disabled-when-admin-state-is-down.patch
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0015-add-support-for-custom-retry.patch
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0016-block-retry-count-changes.patch
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0017-Extend-LACP-fallback-support-to-multiple-ports.patch

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