linux-kernel - Re: [Patch net-next 1/3] net: bridge: mcast: Add offload failed mdb flag

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Message-ID: <85a52bd9-8107-4cb8-b967-2646d0e74ab4@gmail.com>
Date: Wed, 26 Mar 2025 18:38:44 -0400
From: Joseph Huang <joseph.huang.2024@...il.com>
To: Nikolay Aleksandrov <razor@...ckwall.org>,
 Joseph Huang <Joseph.Huang@...min.com>, netdev@...r.kernel.org
Cc: Andrew Lunn <andrew+netdev@...n.ch>, "David S. Miller"
 <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>,
 Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
 Roopa Prabhu <roopa@...dia.com>, Simon Horman <horms@...nel.org>,
 linux-kernel@...r.kernel.org, bridge@...ts.linux.dev
Subject: Re: [Patch net-next 1/3] net: bridge: mcast: Add offload failed mdb
 flag

On 3/21/2025 4:19 AM, Nikolay Aleksandrov wrote:
>> @@ -516,11 +513,14 @@ static void br_switchdev_mdb_complete(struct net_device *dev, int err, void *pri
>>   	     pp = &p->next) {
>>   		if (p->key.port != port)
>>   			continue;
>> -		p->flags |= MDB_PG_FLAGS_OFFLOAD;
>> +
>> +		if (err)
>> +			p->flags |= MDB_PG_FLAGS_OFFLOAD_FAILED;
>> +		else
>> +			p->flags |= MDB_PG_FLAGS_OFFLOAD;
> 
> These two should be mutually exclusive, either it's offloaded or it failed an offload,
> shouldn't be possible to have both set. I'd recommend adding some helper that takes
> care of that.

It is true that these two are mutually exclusive, but strictly speaking 
there are four types of entries:

1. Entries which are not offload-able (i.e., the ports are not backed by 
switchdev)
2. Entries which are being offloaded, but results yet unknown
3. Entries which are successfully offloaded, and
4. Entries which failed to be offloaded

Even if we ignore the ones which are being offloaded (type 2 is 
transient), we still need two flags, otherwise we won't be able to tell 
type 1 from type 4 entries.

If we need two flags anyway, having separate flags for type 3 and type 4 
simplifies the logic.

Or did I misunderstood your comments?

Thanks,
Joseph