netdev - Re: [PATCHv2 net-next] bonding: 3ad: send ifinfo notify when mux state changed

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Date: Wed, 26 Jun 2024 09:25:05 +0300
From: Nikolay Aleksandrov <razor@...ckwall.org>
To: Hangbin Liu <liuhangbin@...il.com>
Cc: netdev@...r.kernel.org, Jay Vosburgh <j.vosburgh@...il.com>,
 Andy Gospodarek <andy@...yhouse.net>, "David S. Miller"
 <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>,
 Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>
Subject: Re: [PATCHv2 net-next] bonding: 3ad: send ifinfo notify when mux
 state changed

On 26/06/2024 04:42, Hangbin Liu wrote:
> On Tue, Jun 25, 2024 at 10:11:53AM +0300, Nikolay Aleksandrov wrote:
>> On 25/06/2024 10:00, Hangbin Liu wrote:
>>> 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 <liuhangbin@...il.com>
>>> ---
>>> v2: don't use call_netdevice_notifiers as it will case sleeping in atomic
>>>     context (Nikolay Aleksandrov)
>>> ---
>>>  drivers/net/bonding/bond_3ad.c | 2 ++
>>>  1 file changed, 2 insertions(+)
>>>
>>> diff --git a/drivers/net/bonding/bond_3ad.c b/drivers/net/bonding/bond_3ad.c
>>> index c6807e473ab7..7a7224bf1894 100644
>>> --- a/drivers/net/bonding/bond_3ad.c
>>> +++ b/drivers/net/bonding/bond_3ad.c
>>> @@ -1185,6 +1185,8 @@ static void ad_mux_machine(struct port *port, bool *update_slave_arr)
>>>  		default:
>>>  			break;
>>>  		}
>>> +
>>> +		rtmsg_ifinfo(RTM_NEWLINK, port->slave->dev, 0, GFP_KERNEL, 0, NULL);
>>>  	}
>>>  }
>>>  
>>
>> GFP_KERNEL still allows to sleep, this is where I meant use GFP_ATOMIC if
>> under the locks in my previous comment.
> 
> Oh, damn! I absolutely agree with you. I did read your last comment and I plan
> to use GFP_ATOMIC. I modified my first version of the patch (that use
> rtmsg_ifinfo directly, which use GFP_KERNEL) but forgot to commit the changes...
> 
> Sorry for the low level mistake...
> 
>> Also how does an administrator undestand that the mux state changed by
>> using the above msg? Could you show the iproute2 part and how it looks for
>> anyone monitoring?
> 
> Do you mean to add the log in the patch description or you want to see it?
> It looks like the following:
> 
> 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> ...
> 
> You can see the actor and partner port state changes.
> 
> Thanks
> Hangbin

Yeah, I just wanted to see how it looks. Feel free to add it to the commit
description but I'm good either way. :)

Cheers,
 Nik