Re: [RFC PATCH net-next 1/5] net: bridge: add dynamic flag to switchdev notifier

From: netdev@kapio-technology.com
To: Vladimir Oltean <olteanv@gmail.com>
Cc: davem@davemloft.net, kuba@kernel.org, netdev@vger.kernel.org,
	"Florian Fainelli" <f.fainelli@gmail.com>,
	"Andrew Lunn" <andrew@lunn.ch>,
	"Eric Dumazet" <edumazet@google.com>,
	"Paolo Abeni" <pabeni@redhat.com>,
	"Kurt Kanzenbach" <kurt@linutronix.de>,
	"Hauke Mehrtens" <hauke@hauke-m.de>,
	"Woojung Huh" <woojung.huh@microchip.com>,
	"maintainer:MICROCHIP KSZ SERIES ETHERNET SWITCH DRIVER"
	<UNGLinuxDriver@microchip.com>,
	"Sean Wang" <sean.wang@mediatek.com>,
	"Landen Chao" <Landen.Chao@mediatek.com>,
	"DENG Qingfang" <dqfext@gmail.com>,
	"Matthias Brugger" <matthias.bgg@gmail.com>,
	"Claudiu Manoil" <claudiu.manoil@nxp.com>,
	"Alexandre Belloni" <alexandre.belloni@bootlin.com>,
	"Clément Léger" <clement.leger@bootlin.com>,
	"Jiri Pirko" <jiri@resnulli.us>,
	"Ivan Vecera" <ivecera@redhat.com>,
	"Roopa Prabhu" <roopa@nvidia.com>,
	"Nikolay Aleksandrov" <razor@blackwall.org>,
	"Russell King" <linux@armlinux.org.uk>,
	"Christian Marangi" <ansuelsmth@gmail.com>,
	"open list" <linux-kernel@vger.kernel.org>,
	"moderated list:ARM/Mediatek SoC support"
	<linux-arm-kernel@lists.infradead.org>,
	"moderated list:ARM/Mediatek SoC support"
	<linux-mediatek@lists.infradead.org>,
	"open list:RENESAS RZ/N1 A5PSW SWITCH DRIVER"
	<linux-renesas-soc@vger.kernel.org>,
	"moderated list:ETHERNET BRIDGE"
	<bridge@lists.linux-foundation.org>
Subject: Re: [RFC PATCH net-next 1/5] net: bridge: add dynamic flag to switchdev notifier
Date: Fri, 20 Jan 2023 22:16:03 +0100	[thread overview]
Message-ID: <29501147c96e7e2f06c999410d42e2bf@kapio-technology.com> (raw)
In-Reply-To: <20230119134045.fqdt6zrna5x3iavt@skbuf>

On 2023-01-19 14:40, Vladimir Oltean wrote:
> On Thu, Jan 19, 2023 at 11:33:58AM +0200, Vladimir Oltean wrote:
>> On Wed, Jan 18, 2023 at 11:14:00PM +0100, netdev@kapio-technology.com 
>> wrote:
>> > > > +	item->is_dyn = !test_bit(BR_FDB_STATIC, &fdb->flags);
>> > >
>> > > Why reverse logic? Why not just name this "is_static" and leave any
>> > > further interpretations up to the consumer?
>> >
>> > My reasoning for this is that the common case is to have static entries,
>> > thus is_dyn=false, so whenever someone uses a switchdev_notifier_fdb_info
>> > struct the common case does not need to be entered.
>> > Otherwise it might also break something when someone uses this struct and if
>> > it was 'is_static' and they forget to code is_static=true they will get
>> > dynamic entries without wanting it and it can be hard to find such an error.
>> 
>> I'll leave it up to bridge maintainers if this is preferable to 
>> patching
>> all callers of SWITCHDEV_FDB_ADD_TO_BRIDGE such that they set 
>> is_static=true.
> 
> Actually, why would you assume that all users of 
> SWITCHDEV_FDB_ADD_TO_BRIDGE
> want to add static FDB entries? You can't avoid inspecting the code and
> making sure that the is_dyn/is_static flag is set correctly either way.

Well, up until this patch set there is no option, besides entries from 
SWITCHDEV_FDB_ADD_TO_BRIDGE events will get the external learned flag 
set, so they will not be aged by the bridge, and so dynamic entries that 
way don't make much sense I think. Is that not right?

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