Re: [PATCH 0/3] Add NETIF_F_HW_BRIDGE feature

From: David Miller <davem@davemloft.net>
To: horatiu.vultur@microchip.com
Cc: roopa@cumulusnetworks.com, nikolay@cumulusnetworks.com,
	UNGLinuxDriver@microchip.com, alexandre.belloni@bootlin.com,
	allan.nielsen@microchip.com, netdev@vger.kernel.org,
	linux-kernel@vger.kernel.org, bridge@lists.linux-foundation.org
Subject: Re: [PATCH 0/3] Add NETIF_F_HW_BRIDGE feature
Date: Thu, 22 Aug 2019 15:32:09 -0700 (PDT)	[thread overview]
Message-ID: <20190822.153209.365750764799027706.davem@davemloft.net> (raw)
In-Reply-To: <1566500850-6247-1-git-send-email-horatiu.vultur@microchip.com>

From: Horatiu Vultur <horatiu.vultur@microchip.com>
Date: Thu, 22 Aug 2019 21:07:27 +0200

> Current implementation of the SW bridge is setting the interfaces in
> promisc mode when they are added to bridge if learning of the frames is
> enabled.
> In case of Ocelot which has HW capabilities to switch frames, it is not
> needed to set the ports in promisc mode because the HW already capable of
> doing that. Therefore add NETIF_F_HW_BRIDGE feature to indicate that the
> HW has bridge capabilities. Therefore the SW bridge doesn't need to set
> the ports in promisc mode to do the switching.
> This optimization takes places only if all the interfaces that are part
> of the bridge have this flag and have the same network driver.
> 
> If the bridge interfaces is added in promisc mode then also the ports part
> of the bridge are set in promisc mode.

This doesn't look right at all.

The Linux bridge provides a software bridge.

By default, all hardware must provide a hardware implementation of
that software bridge behavior.

Anything that deviates from that behavior has to be explicitly asked
for by the user by explicit config commands.