Re: [PATCH RFC v1 net-next 11/12] bridge: br_vlan_fill_forward_path_mode no _UNTAG_HW for dsa

[Nikolay Aleksandrov <razor@blackwall.org>]

On 14/10/2024 09:18, Nikolay Aleksandrov wrote:
> On 13/10/2024 21:55, Eric Woudstra wrote:
>> In network setup as below:
>>
>>              fastpath bypass
>>  .----------------------------------------.
>> /                                          \
>> |                        IP - forwarding    |
>> |                       /                \  v
>> |                      /                  wan ...
>> |                     /
>> |                     |
>> |                     |
>> |                   brlan.1
>> |                     |
>> |    +-------------------------------+
>> |    |           vlan 1              |
>> |    |                               |
>> |    |     brlan (vlan-filtering)    |
>> |    |               +---------------+
>> |    |               |  DSA-SWITCH   |
>> |    |    vlan 1     |               |
>> |    |      to       |               |
>> |    |   untagged    1     vlan 1    |
>> |    +---------------+---------------+
>> .         /                   \
>>  ----->wlan1                 lan0
>>        .                       .
>>        .                       ^
>>        ^                     vlan 1 tagged packets
>>      untagged packets
>>
>> Now that DEV_PATH_MTK_WDMA is added to nft_dev_path_info() the forward
>> path is filled also when ending with the mediatek wlan1, info.indev not
>> NULL now in nft_dev_forward_path(). This results in a direct transmit
>> instead of a neighbor transmit. This is how it should be, But this fails.
>>
>> br_vlan_fill_forward_path_mode() sets DEV_PATH_BR_VLAN_UNTAG_HW when
>> filling in from brlan.1 towards wlan1. But it should be set to
>> DEV_PATH_BR_VLAN_UNTAG in this case. Using BR_VLFLAG_ADDED_BY_SWITCHDEV
>> is not correct. The dsa switchdev adds it as a foreign port.
>>
>> Use BR_VLFLAG_TAGGING_BY_SWITCHDEV to make sure DEV_PATH_BR_VLAN_UNTAG is
>> set when there is a dsa-switch inside the bridge.
>>
>> Signed-off-by: Eric Woudstra <ericwouds@gmail.com>
>> ---
>>  net/bridge/br_private.h |  1 +
>>  net/bridge/br_vlan.c    | 18 +++++++++++++++++-
>>  2 files changed, 18 insertions(+), 1 deletion(-)
>>
>> diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
>> index 8da7798f9368..7d427214cc7c 100644
>> --- a/net/bridge/br_private.h
>> +++ b/net/bridge/br_private.h
>> @@ -180,6 +180,7 @@ enum {
>>  	BR_VLFLAG_MCAST_ENABLED = BIT(2),
>>  	BR_VLFLAG_GLOBAL_MCAST_ENABLED = BIT(3),
>>  	BR_VLFLAG_NEIGH_SUPPRESS_ENABLED = BIT(4),
>> +	BR_VLFLAG_TAGGING_BY_SWITCHDEV = BIT(5),
>>  };
>>  
>>  /**
>> diff --git a/net/bridge/br_vlan.c b/net/bridge/br_vlan.c
>> index 1830d7d617cd..b7877724b969 100644
>> --- a/net/bridge/br_vlan.c
>> +++ b/net/bridge/br_vlan.c
>> @@ -3,6 +3,7 @@
>>  #include <linux/netdevice.h>
>>  #include <linux/rtnetlink.h>
>>  #include <linux/slab.h>
>> +#include <net/dsa.h>
>>  #include <net/switchdev.h>
>>  
>>  #include "br_private.h"
>> @@ -100,6 +101,19 @@ static void __vlan_flags_commit(struct net_bridge_vlan *v, u16 flags)
>>  	__vlan_flags_update(v, flags, true);
>>  }
>>  
>> +static inline bool br_vlan_tagging_by_switchdev(struct net_bridge *br)
> 
> no inline in .c files and also constify br
> 
>> +{
>> +#if IS_ENABLED(CONFIG_NET_DSA)
>> +	struct net_bridge_port *p;
>> +
>> +	list_for_each_entry(p, &br->port_list, list) {
>> +		if (dsa_user_dev_check(p->dev))
> 
> I don't think this can change at runtime, so please keep a counter in
> the bridge and don't walk the port list on every vlan add.
> 

you can use an internal bridge opt (check br_private.h) with a private opt
that's set when such device is added as a port, no need for a full counter
obviously

>> +			return false;
>> +	}
>> +#endif
>> +	return true;
>> +}
>> +
>>  static int __vlan_vid_add(struct net_device *dev, struct net_bridge *br,
>>  			  struct net_bridge_vlan *v, u16 flags,
>>  			  struct netlink_ext_ack *extack)
>> @@ -113,6 +127,8 @@ static int __vlan_vid_add(struct net_device *dev, struct net_bridge *br,
>>  	if (err == -EOPNOTSUPP)
>>  		return vlan_vid_add(dev, br->vlan_proto, v->vid);
>>  	v->priv_flags |= BR_VLFLAG_ADDED_BY_SWITCHDEV;
>> +	if (br_vlan_tagging_by_switchdev(br))
>> +		v->priv_flags |= BR_VLFLAG_TAGGING_BY_SWITCHDEV;
>>  	return err;
>>  }
>>  
>> @@ -1491,7 +1507,7 @@ int br_vlan_fill_forward_path_mode(struct net_bridge *br,
>>  
>>  	if (path->bridge.vlan_mode == DEV_PATH_BR_VLAN_TAG)
>>  		path->bridge.vlan_mode = DEV_PATH_BR_VLAN_KEEP;
>> -	else if (v->priv_flags & BR_VLFLAG_ADDED_BY_SWITCHDEV)
>> +	else if (v->priv_flags & BR_VLFLAG_TAGGING_BY_SWITCHDEV)
>>  		path->bridge.vlan_mode = DEV_PATH_BR_VLAN_UNTAG_HW;
>>  	else
>>  		path->bridge.vlan_mode = DEV_PATH_BR_VLAN_UNTAG;
>