This patch tries to avoid the possible peer notify event loss.

In bond_mii_monitor()/bond_activebackup_arp_mon(), when we hold the rtnl lock:
- check send_peer_notif again to avoid unconditionally reducing this value.
- send_peer_notif may have been reset. Therefore, it is necessary to check
  whether to send peer notify via bond_should_notify_peers() to avoid the
  loss of notification events.

Cc: Jay Vosburgh <jv@jvosburgh.net>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: Simon Horman <horms@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Andrew Lunn <andrew+netdev@lunn.ch>
Cc: Nikolay Aleksandrov <razor@blackwall.org>
Cc: Hangbin Liu <liuhangbin@gmail.com>
Cc: Jason Xing <kerneljasonxing@gmail.com>
Signed-off-by: Tonghao Zhang <tonghao@bamaicloud.com>
Reviewed-by: Hangbin Liu <liuhangbin@gmail.com>
---
v2-4:
- no change
v1:
- splitted from: https://patchwork.kernel.org/project/netdevbpf/patch/20251118090431.35654-1-tonghao@bamaicloud.com/
- this patch only move the bond_should_notify_peers to rtnl lock.
- add this patch to series
---
 drivers/net/bonding/bond_main.c | 25 ++++++++++---------------
 1 file changed, 10 insertions(+), 15 deletions(-)

diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index edf6dac8a98f..8be7f52e847c 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -2809,11 +2809,10 @@ static void bond_mii_monitor(struct work_struct *work)
 {
 	struct bonding *bond = container_of(work, struct bonding,
 					    mii_work.work);
-	bool should_notify_peers;
-	bool commit;
-	unsigned long delay;
-	struct slave *slave;
 	struct list_head *iter;
+	struct slave *slave;
+	unsigned long delay;
+	bool commit;
 
 	delay = msecs_to_jiffies(bond->params.miimon);
 
@@ -2822,7 +2821,6 @@ static void bond_mii_monitor(struct work_struct *work)
 
 	rcu_read_lock();
 
-	should_notify_peers = bond_should_notify_peers(bond);
 	commit = !!bond_miimon_inspect(bond);
 
 	rcu_read_unlock();
@@ -2843,10 +2841,10 @@ static void bond_mii_monitor(struct work_struct *work)
 		}
 
 		if (bond->send_peer_notif) {
-			bond->send_peer_notif--;
-			if (should_notify_peers)
+			if (bond_should_notify_peers(bond))
 				call_netdevice_notifiers(NETDEV_NOTIFY_PEERS,
 							 bond->dev);
+			bond->send_peer_notif--;
 		}
 
 		rtnl_unlock();	/* might sleep, hold no other locks */
@@ -3758,7 +3756,6 @@ static bool bond_ab_arp_probe(struct bonding *bond)
 
 static void bond_activebackup_arp_mon(struct bonding *bond)
 {
-	bool should_notify_peers = false;
 	bool should_notify_rtnl = false;
 	int delta_in_ticks;
 
@@ -3769,15 +3766,12 @@ static void bond_activebackup_arp_mon(struct bonding *bond)
 
 	rcu_read_lock();
 
-	should_notify_peers = bond_should_notify_peers(bond);
-
 	if (bond_ab_arp_inspect(bond)) {
 		rcu_read_unlock();
 
 		/* Race avoidance with bond_close flush of workqueue */
 		if (!rtnl_trylock()) {
 			delta_in_ticks = 1;
-			should_notify_peers = false;
 			goto re_arm;
 		}
 
@@ -3794,14 +3788,15 @@ static void bond_activebackup_arp_mon(struct bonding *bond)
 	if (bond->params.arp_interval)
 		queue_delayed_work(bond->wq, &bond->arp_work, delta_in_ticks);
 
-	if (should_notify_peers || should_notify_rtnl) {
+	if (bond->send_peer_notif || should_notify_rtnl) {
 		if (!rtnl_trylock())
 			return;
 
-		if (should_notify_peers) {
+		if (bond->send_peer_notif) {
+			if (bond_should_notify_peers(bond))
+				call_netdevice_notifiers(NETDEV_NOTIFY_PEERS,
+							 bond->dev);
 			bond->send_peer_notif--;
-			call_netdevice_notifiers(NETDEV_NOTIFY_PEERS,
-						 bond->dev);
 		}
 		if (should_notify_rtnl) {
 			bond_slave_state_notify(bond);
-- 
2.34.1