linux-kernel - Re: [PATCH net-next 4/4] net/mlx5: Lag, add net namespace support

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Message-ID: <5af63b6d-8609-4799-83b7-fa3daca390bb@nvidia.com>
Date: Sat, 13 Sep 2025 04:52:17 +0300
From: Mark Bloch <mbloch@...dia.com>
To: Simon Horman <horms@...nel.org>, Tariq Toukan <tariqt@...dia.com>
Cc: Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>,
 Paolo Abeni <pabeni@...hat.com>, Andrew Lunn <andrew+netdev@...n.ch>,
 "David S. Miller" <davem@...emloft.net>, Saeed Mahameed <saeedm@...dia.com>,
 Leon Romanovsky <leon@...nel.org>, netdev@...r.kernel.org,
 linux-rdma@...r.kernel.org, linux-kernel@...r.kernel.org,
 Gal Pressman <gal@...dia.com>, Parav Pandit <parav@...dia.com>,
 Shay Drory <shayd@...dia.com>
Subject: Re: [PATCH net-next 4/4] net/mlx5: Lag, add net namespace support

On 12/09/2025 17:09, Simon Horman wrote:
> On Thu, Sep 11, 2025 at 09:31:07AM +0300, Tariq Toukan wrote:
>> From: Shay Drory <shayd@...dia.com>
>>
>> Update the LAG implementation to support net namespace isolation.
>>
>> With recent changes to the devcom framework allowing namespace-aware
>> matching, the LAG layer is updated to register devcom clients with the
>> associated net namespace. This ensures that LAG formation only occurs
>> between mlx5 interfaces that reside in the same namespace.
>>
>> This change ensures that devices in different namespaces do not interfere
>> with each other's LAG setup and behavior. For example, if two PCI PFs are
>> in the same namespace, they are eligible to form a hardware LAG.
>>
>> In addition, reload behavior for LAG is adjusted to handle namespace
>> contexts appropriately.
>>
>> Signed-off-by: Shay Drory <shayd@...dia.com>
>> Reviewed-by: Mark Bloch <mbloch@...dia.com>
>> Reviewed-by: Parav Pandit <parav@...dia.com>
>> Signed-off-by: Tariq Toukan <tariqt@...dia.com>
>> ---
>>  drivers/net/ethernet/mellanox/mlx5/core/devlink.c |  5 -----
>>  drivers/net/ethernet/mellanox/mlx5/core/lag/lag.c | 14 +++++++++++---
>>  drivers/net/ethernet/mellanox/mlx5/core/lag/lag.h |  1 +
>>  3 files changed, 12 insertions(+), 8 deletions(-)
>>
>> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/devlink.c b/drivers/net/ethernet/mellanox/mlx5/core/devlink.c
>> index a0b68321355a..bfa44414be82 100644
>> --- a/drivers/net/ethernet/mellanox/mlx5/core/devlink.c
>> +++ b/drivers/net/ethernet/mellanox/mlx5/core/devlink.c
>> @@ -204,11 +204,6 @@ static int mlx5_devlink_reload_down(struct devlink *devlink, bool netns_change,
>>  		return 0;
>>  	}
>>  
>> -	if (mlx5_lag_is_active(dev)) {
>> -		NL_SET_ERR_MSG_MOD(extack, "reload is unsupported in Lag mode");
>> -		return -EOPNOTSUPP;
>> -	}
>> -
> 
> Maybe I'm missing something obvious. But I think this could do with
> some further commentary in the commit message. Or perhaps being a separate
> patch.

While one could split this into two patches, first enabling LAG creation
within a namespace, then separately removing the devlink reload restriction
that separation feels artificial.

Both changes are required to deliver complete support for LAG in namespaces
Since removing the reload restriction is a trivial change, it is better
to deliver the entire feature in this single patch.

Will clarify and add this justification to the commit message.

> 
>>  	if (mlx5_core_is_mp_slave(dev)) {
>>  		NL_SET_ERR_MSG_MOD(extack, "reload is unsupported for multi port slave");
>>  		return -EOPNOTSUPP;
> 
> ...
> 
>> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/lag/lag.h b/drivers/net/ethernet/mellanox/mlx5/core/lag/lag.h
>> index c2f256bb2bc2..4918eee2b3da 100644
>> --- a/drivers/net/ethernet/mellanox/mlx5/core/lag/lag.h
>> +++ b/drivers/net/ethernet/mellanox/mlx5/core/lag/lag.h
>> @@ -67,6 +67,7 @@ struct mlx5_lag {
>>  	struct workqueue_struct   *wq;
>>  	struct delayed_work       bond_work;
>>  	struct notifier_block     nb;
>> +	possible_net_t net;
> 
> nit: inconsistent indentation.

I prefer to avoid vertical alignment. I find that style
is often brittle and makes the code harder to maintain
over time.

Thanks for the review!
Mark

> 
>>  	struct lag_mp             lag_mp;
>>  	struct mlx5_lag_port_sel  port_sel;
>>  	/* Protect lag fields/state changes */
>> -- 
>> 2.31.1
>>
>>