Re: [PATCH net-next 2/6] software node: allow named software node to be created

From: "Russell King (Oracle)" <linux@armlinux.org.uk>
To: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: "Vladimir Oltean" <olteanv@gmail.com>,
	"Andrew Lunn" <andrew@lunn.ch>,
	"Heiner Kallweit" <hkallweit1@gmail.com>,
	"Alexandre Belloni" <alexandre.belloni@bootlin.com>,
	"Alvin __ipraga" <alsi@bang-olufsen.dk>,
	"Claudiu Manoil" <claudiu.manoil@nxp.com>,
	"Daniel Scally" <djrscally@gmail.com>,
	"David S. Miller" <davem@davemloft.net>,
	"DENG Qingfang" <dqfext@gmail.com>,
	"Eric Dumazet" <edumazet@google.com>,
	"Florian Fainelli" <f.fainelli@gmail.com>,
	"George McCollister" <george.mccollister@gmail.com>,
	"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
	"Hauke Mehrtens" <hauke@hauke-m.de>,
	"Heikki Krogerus" <heikki.krogerus@linux.intel.com>,
	"Jakub Kicinski" <kuba@kernel.org>,
	"Kurt Kanzenbach" <kurt@linutronix.de>,
	"Landen Chao" <Landen.Chao@mediatek.com>,
	"Linus Walleij" <linus.walleij@linaro.org>,
	linux-acpi@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-mediatek@lists.infradead.org,
	"Matthias Brugger" <matthias.bgg@gmail.com>,
	netdev@vger.kernel.org, "Paolo Abeni" <pabeni@redhat.com>,
	"Rafael J. Wysocki" <rafael@kernel.org>,
	"Sakari Ailus" <sakari.ailus@linux.intel.com>,
	"Sean Wang" <sean.wang@mediatek.com>,
	UNGLinuxDriver@microchip.com,
	"Vivien Didelot" <vivien.didelot@gmail.com>,
	"Woojung Huh" <woojung.huh@microchip.com>,
	"Marek Behún" <kabel@kernel.org>
Subject: Re: [PATCH net-next 2/6] software node: allow named software node to be created
Date: Mon, 18 Jul 2022 14:27:02 +0100	[thread overview]
Message-ID: <YtVfppMtW77ICyC5@shell.armlinux.org.uk> (raw)
In-Reply-To: <YtVSQI5VHtCOTCHc@smile.fi.intel.com>

On Mon, Jul 18, 2022 at 03:29:52PM +0300, Andy Shevchenko wrote:
> On Fri, Jul 15, 2022 at 11:48:41PM +0300, Vladimir Oltean wrote:
> > So won't kobject_init_and_add() fail on namespace collision? Is it the
> > problem that it's going to fail, or that it's not trivial to statically
> > determine whether it'll fail?
> > 
> > Sorry, but I don't see something actionable about this.
> 
> I'm talking about validation before a runtime. But if you think that is fine,
> let's fail it at runtime, okay, and consume more backtraces in the future.

Is there any sane way to do validation of this namespace before
runtime?

The problem in this instance is we need a node named "fixed-link" that
is attached to the parent node as that is defined in the binding doc,
and we're creating swnodes to provide software generated nodes for
this binding.

There could be several such nodes scattered around, but in this
instance they are very short-lived before they are destroyed, they
don't even need to be published to userspace (and its probably a waste
of CPU cycles for them to be published there.)

So, for this specific case, is this the best approach, or is there
some better way to achieve what we need here?

Thanks.

-- 
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