Re: [PATCHv3 net-next] bonding: 3ad: send ifinfo notify when mux state changed

Currently, administrators need to retrieve LACP mux state changes from
the kernel DEBUG log using netdev_dbg and slave_dbg macros. To simplify
this process, let's send the ifinfo notification whenever the mux state
changes. This will enable users to directly access and monitor this
information using the ip monitor command.

Signed-off-by: Hangbin Liu <redacted>
---
v3: forgot to use GFP_ATOMIC. (Nikolay Aleksandrov)
    export symbol for rtmsg_ifinfo. It's weird that my build succeed with
    tools/testing/selftests/drivers/net/bonding/config without export
    the symbol, but build failed with tools/testing/selftests/net/config.
v2: don't use call_netdevice_notifiers as it will case sleeping in atomic
    context (Nikolay Aleksandrov)

After this patch, we can see the following info with `ip -d monitor link`

7: veth1@if6: <BROADCAST,MULTICAST,SLAVE,UP,LOWER_UP> mtu 1500 qdisc noqueue master bond0 state UP group default
    link/ether 02:0a:04:c2:d6:21 brd ff:ff:ff:ff:ff:ff link-netns b promiscuity 0 allmulti 0 minmtu 68 maxmtu 65535
    veth
    bond_slave state BACKUP mii_status UP ... ad_aggregator_id 1 ad_actor_oper_port_state 143 ad_actor_oper_port_state_str <active,short_timeout,aggregating,in_sync,expired> ad_partner_oper_port_state 55 ad_partner_oper_port_state_str <active,short_timeout,aggregating,collecting,distributing> ...
7: veth1@if6: <BROADCAST,MULTICAST,SLAVE,UP,LOWER_UP> mtu 1500 qdisc noqueue master bond0 state UP group default
    link/ether 02:0a:04:c2:d6:21 brd ff:ff:ff:ff:ff:ff link-netns b promiscuity 0 allmulti 0 minmtu 68 maxmtu 65535
    veth
    bond_slave state ACTIVE mii_status UP ... ad_aggregator_id 1 ad_actor_oper_port_state 79 ad_actor_oper_port_state_str <active,short_timeout,aggregating,in_sync,defaulted> ad_partner_oper_port_state 1 ad_partner_oper_port_state_str <active> ...
7: veth1@if6: <BROADCAST,MULTICAST,SLAVE,UP,LOWER_UP> mtu 1500 qdisc noqueue master bond0 state UP group default
    link/ether 02:0a:04:c2:d6:21 brd ff:ff:ff:ff:ff:ff link-netns b promiscuity 0 allmulti 0 minmtu 68 maxmtu 65535
    veth
    bond_slave state ACTIVE mii_status UP ... ad_aggregator_id 1 ad_actor_oper_port_state 63 ad_actor_oper_port_state_str <active,short_timeout,aggregating,in_sync,collecting,distributing> ad_partner_oper_port_state 63 ad_partner_oper_port_state_str <active,short_timeout,aggregating,in_sync,collecting,distributing> ...
---
 drivers/net/bonding/bond_3ad.c | 3 +++
 net/core/rtnetlink.c           | 1 +
 2 files changed, 4 insertions(+)

diff --git a/drivers/net/bonding/bond_3ad.c b/drivers/net/bonding/bond_3ad.c
index c6807e473ab7..b57c5670b31a 100644
--- a/drivers/net/bonding/bond_3ad.c
+++ b/drivers/net/bonding/bond_3ad.c

@@ -11,6 +11,7 @@
 #include <linux/etherdevice.h>
 #include <linux/if_bonding.h>
 #include <linux/pkt_sched.h>
+#include <linux/rtnetlink.h>
 #include <net/net_namespace.h>
 #include <net/bonding.h>
 #include <net/bond_3ad.h>

@@ -1185,6 +1186,8 @@ static void ad_mux_machine(struct port *port, bool *update_slave_arr)
 		default:
 			break;
 		}
+
+		rtmsg_ifinfo(RTM_NEWLINK, port->slave->dev, 0, GFP_ATOMIC, 0, NULL);
 	}
 }
 

diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index eabfc8290f5e..4507bb8d5264 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c

@@ -4116,6 +4116,7 @@ void rtmsg_ifinfo(int type, struct net_device *dev, unsigned int change,
 	rtmsg_ifinfo_event(type, dev, change, rtnl_get_event(0), flags,
 			   NULL, 0, portid, nlh);
 }
+EXPORT_SYMBOL(rtmsg_ifinfo);
 
 void rtmsg_ifinfo_newnet(int type, struct net_device *dev, unsigned int change,
 			 gfp_t flags, int *new_nsid, int new_ifindex)