net: bonding: use workqueue to make sure peer notify updated in lacp mode

The rtnl lock might be locked, preventing ad_cond_set_peer_notif() from
acquiring the lock and updating send_peer_notif. This patch addresses
the issue by using a workqueue. Since updating send_peer_notif does
not require high real-time performance, such delayed updates are entirely
acceptable.

In fact, checking this value and using it in multiple places, all operations
are protected at the same time by rtnl lock, such as
- read send_peer_notif
- send_peer_notif--
- bond_should_notify_peers

By the way, rtnl lock is still required, when accessing bond.params.* for
updating send_peer_notif. In lacp mode, resetting send_peer_notif in
workqueue is safe, simple and effective way.

Additionally, this patch introduces bond_peer_notify_may_events(), which
is used to check whether an event should be sent. This function will be
used in both patch 1 and 2.

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>
Suggested-by: Hangbin Liu <liuhangbin@gmail.com>
Signed-off-by: Tonghao Zhang <tonghao@bamaicloud.com>
Reviewed-by: Hangbin Liu <liuhangbin@gmail.com>
Link: https://patch.msgid.link/f95accb5db0b10ce3ed2f834fc70f716c9abbb9c.1768709239.git.tonghao@bamaicloud.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/include/net/bonding.h b/include/net/bonding.h
index 49edc7da0586..63d08056a4a4 100644
--- a/include/net/bonding.h
+++ b/include/net/bonding.h
@@ -254,6 +254,7 @@ struct bonding {
 	struct   delayed_work ad_work;
 	struct   delayed_work mcast_work;
 	struct   delayed_work slave_arr_work;
+	struct   delayed_work peer_notify_work;
 #ifdef CONFIG_DEBUG_FS
 	/* debugging support via debugfs */
 	struct	 dentry *debug_dir;
@@ -709,6 +710,7 @@ struct bond_vlan_tag *bond_verify_device_path(struct net_device *start_dev,
 					      int level);
 int bond_update_slave_arr(struct bonding *bond, struct slave *skipslave);
 void bond_slave_arr_work_rearm(struct bonding *bond, unsigned long delay);
+void bond_peer_notify_work_rearm(struct bonding *bond, unsigned long delay);
 void bond_work_init_all(struct bonding *bond);
 void bond_work_cancel_all(struct bonding *bond);