Re: [PATCH net-next 2/9] net: bridge: offload initial and final port flags through switchdev

From: Vladimir Oltean <olteanv@gmail.com>
To: Nikolay Aleksandrov <nikolay@nvidia.com>
Cc: Jakub Kicinski <kuba@kernel.org>,
	"David S. Miller" <davem@davemloft.net>,
	Andrew Lunn <andrew@lunn.ch>,
	Vivien Didelot <vivien.didelot@gmail.com>,
	Florian Fainelli <f.fainelli@gmail.com>,
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	bridge@lists.linux-foundation.org,
	Roopa Prabhu <roopa@nvidia.com>, Jiri Pirko <jiri@resnulli.us>,
	Ido Schimmel <idosch@idosch.org>,
	Claudiu Manoil <claudiu.manoil@nxp.com>,
	Alexandre Belloni <alexandre.belloni@bootlin.com>,
	UNGLinuxDriver@microchip.com, Vadym Kochan <vkochan@marvell.com>,
	Taras Chornyi <tchornyi@marvell.com>,
	Grygorii Strashko <grygorii.strashko@ti.com>,
	Ioana Ciornei <ioana.ciornei@nxp.com>,
	Ivan Vecera <ivecera@redhat.com>,
	linux-omap@vger.kernel.org
Subject: Re: [PATCH net-next 2/9] net: bridge: offload initial and final port flags through switchdev
Date: Mon, 8 Feb 2021 13:45:11 +0200	[thread overview]
Message-ID: <20210208114511.xtzma5byrdnr5s7r@skbuf> (raw)
In-Reply-To: <95dede91-56aa-1852-8fbf-71d446fa7ede@nvidia.com>

On Mon, Feb 08, 2021 at 01:37:03PM +0200, Nikolay Aleksandrov wrote:
> Hi Vladimir,
> I think this patch potentially breaks some use cases. There are a few problems, I'll
> start with the more serious one: before the ports would have a set of flags that were
> always set when joining, now due to how nbp_flags_change() handles flag setting some might
> not be set which would immediately change behaviour w.r.t software fwding. I'll use your
> example of BR_BCAST_FLOOD: a lot of drivers will return an error for it and any broadcast
> towards these ports will be dropped, we have mixed environments with software ports that
> sometimes have traffic (e.g. decapped ARP requests) software forwarded which will stop working.

Yes, you're right. The only solution I can think of is to add a "bool ignore_errors"
to nbp_flags_change, set to true from new_nbp and del_nbp, and to false from the
netlink code.

> The other lesser issue is with the style below, I mean these three calls for each flag are
> just ugly and look weird as you've also noted, since these APIs are internal can we do better?

Doing better would mean allowing nbp_flags_change() to have a bit mask with
potentially more brport flags set, and to call br_switchdev_set_port_flag in
a for_each_set_bit() loop?