netdev - Re: [PATCH net-next] net: dsa: sja1105: make devlink property best_effort_vlan

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Message-ID: <2dd5efde-0188-e88f-7885-3ba10ea0358c@gmail.com>
Date:   Sat, 13 Feb 2021 17:18:54 -0800
From:   Florian Fainelli <f.fainelli@...il.com>
To:     Vladimir Oltean <olteanv@...il.com>,
        "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>, netdev@...r.kernel.org
Cc:     Andrew Lunn <andrew@...n.ch>,
        Vivien Didelot <vivien.didelot@...il.com>
Subject: Re: [PATCH net-next] net: dsa: sja1105: make devlink property
 best_effort_vlan_filtering true by default



On 2/13/2021 12:46, Vladimir Oltean wrote:
> From: Vladimir Oltean <vladimir.oltean@....com>
> 
> The sja1105 driver has a limitation, extensively described under
> Documentation/networking/dsa/sja1105.rst and
> Documentation/networking/devlink/sja1105.rst, which says that when the
> ports are under a bridge with vlan_filtering=1, traffic to and from
> the network stack is not possible, unless the driver-specific
> best_effort_vlan_filtering devlink parameter is enabled.
> 
> For users, this creates a 'wtf' moment. They need to go to the
> documentation and find about the existence of this property, then maybe
> install devlink and set it to true.
> 
> Having best_effort_vlan_filtering enabled by the kernel by default
> delays that 'wtf' moment (maybe up to the point that it never even
> happens). The user doesn't need to care that the driver supports
> addressing the ports individually by retagging VLAN IDs until he/she
> needs to use more than 32 VLAN IDs (since there can be at most 32
> retagging rules). Only then do they need to think whether they need the
> full VLAN table, at the expense of no individual port addressing, or
> not.
> 
> But the odds that an sja1105 user will need more than 32 VLANs
> terminated by the CPU is probably low. And, if we were to follow the
> principle that more advanced use cases should require more advanced
> preparation steps, then it makes more sense for ping to 'just work'
> while CPU termination of > 32 VLAN IDs to require a bit more forethought
> and possibly a driver-specific devlink param.
> 
> So we should be able to safely change the default here, and make this
> driver act just a little bit more sanely out of the box.
> 
> Signed-off-by: Vladimir Oltean <vladimir.oltean@....com>

Reviewed-by: Florian Fainelli <f.fainelli@...il.com>
-- 
Florian