[PATCHv4 net-next 2/3] bonding: support aggregator selection based on port priority

[Hangbin Liu <liuhangbin@gmail.com>]

Add a new ad_select policy 'port_priority' that uses the per-port
actor priority values (set via ad_actor_port_prio) to determine
aggregator selection.

This allows administrators to influence which ports are preferred
for aggregation by assigning different priority values, providing
more flexible load balancing control in LACP configurations.

Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
---
 Documentation/networking/bonding.rst |  9 ++++++++-
 drivers/net/bonding/bond_3ad.c       | 27 +++++++++++++++++++++++++++
 drivers/net/bonding/bond_options.c   |  1 +
 include/net/bond_3ad.h               |  1 +
 4 files changed, 37 insertions(+), 1 deletion(-)

diff --git a/Documentation/networking/bonding.rst b/Documentation/networking/bonding.rst
index 1ca7830c24ea..10d952c3c225 100644
--- a/Documentation/networking/bonding.rst
+++ b/Documentation/networking/bonding.rst
@@ -250,7 +250,14 @@ ad_select
 		ports (slaves).  Reselection occurs as described under the
 		"bandwidth" setting, above.
 
-	The bandwidth and count selection policies permit failover of
+	prio or 3
+
+		The active aggregator is chosen by the highest total sum of
+		actor port priorities across its active ports. Note this
+		priority is actor_port_prio, not per port prio, which is
+		used for primary reselect.
+
+	The bandwidth, count and prio selection policies permit failover of
 	802.3ad aggregations when partial failure of the active aggregator
 	occurs.  This keeps the aggregator with the highest availability
 	(either in bandwidth or in number of ports) active at all times.
diff --git a/drivers/net/bonding/bond_3ad.c b/drivers/net/bonding/bond_3ad.c
index 67ca78923b04..49717b7b82a2 100644
--- a/drivers/net/bonding/bond_3ad.c
+++ b/drivers/net/bonding/bond_3ad.c
@@ -747,6 +747,18 @@ static int __agg_active_ports(struct aggregator *agg)
 	return active;
 }
 
+static unsigned int __agg_ports_priority(const struct aggregator *agg)
+{
+	struct port *port = agg->lag_ports;
+	unsigned int prio = 0;
+
+	for (; port; port = port->next_port_in_aggregator)
+		if (port->is_enabled)
+			prio += port->actor_port_priority;
+
+	return prio;
+}
+
 /**
  * __get_agg_bandwidth - get the total bandwidth of an aggregator
  * @aggregator: the aggregator we're looking at
@@ -1708,6 +1720,9 @@ static struct aggregator *ad_agg_selection_test(struct aggregator *best,
 	 * 4.  Therefore, current and best both have partner replies or
 	 *     both do not, so perform selection policy:
 	 *
+	 * BOND_AD_PRIO: Select by total priority of ports. If priority
+	 *     is equal, select by count.
+	 *
 	 * BOND_AD_COUNT: Select by count of ports.  If count is equal,
 	 *     select by bandwidth.
 	 *
@@ -1729,6 +1744,14 @@ static struct aggregator *ad_agg_selection_test(struct aggregator *best,
 		return best;
 
 	switch (__get_agg_selection_mode(curr->lag_ports)) {
+	case BOND_AD_PRIO:
+		if (__agg_ports_priority(curr) > __agg_ports_priority(best))
+			return curr;
+
+		if (__agg_ports_priority(curr) < __agg_ports_priority(best))
+			return best;
+
+		fallthrough;
 	case BOND_AD_COUNT:
 		if (__agg_active_ports(curr) > __agg_active_ports(best))
 			return curr;
@@ -1794,6 +1817,10 @@ static int agg_device_up(const struct aggregator *agg)
  * (slaves), and reselect whenever a link state change takes place or the
  * set of slaves in the bond changes.
  *
+ * BOND_AD_PRIO: select the aggregator with highest total priority of ports
+ * (slaves), and reselect whenever a link state change takes place or the
+ * set of slaves in the bond changes.
+ *
  * FIXME: this function MUST be called with the first agg in the bond, or
  * __get_active_agg() won't work correctly. This function should be better
  * called with the bond itself, and retrieve the first agg from it.
diff --git a/drivers/net/bonding/bond_options.c b/drivers/net/bonding/bond_options.c
index 7cc9b033095b..ee549c96945b 100644
--- a/drivers/net/bonding/bond_options.c
+++ b/drivers/net/bonding/bond_options.c
@@ -165,6 +165,7 @@ static const struct bond_opt_value bond_ad_select_tbl[] = {
 	{ "stable",    BOND_AD_STABLE,    BOND_VALFLAG_DEFAULT},
 	{ "bandwidth", BOND_AD_BANDWIDTH, 0},
 	{ "count",     BOND_AD_COUNT,     0},
+	{ "prio",      BOND_AD_PRIO,      0},
 	{ NULL,        -1,                0},
 };
 
diff --git a/include/net/bond_3ad.h b/include/net/bond_3ad.h
index e9188646e22e..c92d4a976246 100644
--- a/include/net/bond_3ad.h
+++ b/include/net/bond_3ad.h
@@ -26,6 +26,7 @@ enum {
 	BOND_AD_STABLE = 0,
 	BOND_AD_BANDWIDTH = 1,
 	BOND_AD_COUNT = 2,
+	BOND_AD_PRIO = 3,
 };
 
 /* rx machine states(43.4.11 in the 802.3ad standard) */
-- 
2.50.1