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Date: Sat, 14 Mar 2026 07:54:27 -0700
From: Jakub Kicinski <kuba@kernel.org>
To: =?UTF-8?B?VGjDqW8=?= Lebrun <theo.lebrun@bootlin.com>
Cc: "Nicolas Ferre" <nicolas.ferre@microchip.com>, "Claudiu Beznea"
 <claudiu.beznea@tuxon.dev>, "Andrew Lunn" <andrew+netdev@lunn.ch>, "David
 S. Miller" <davem@davemloft.net>, "Eric Dumazet" <edumazet@google.com>,
 "Paolo Abeni" <pabeni@redhat.com>, <netdev@vger.kernel.org>,
 <linux-kernel@vger.kernel.org>, "Vladimir Kondratiev"
 <vladimir.kondratiev@mobileye.com>, "Gregory CLEMENT"
 <gregory.clement@bootlin.com>, =?UTF-8?B?QmVub8OudA==?= Monin
 <benoit.monin@bootlin.com>, "Tawfik Bayouk" <tawfik.bayouk@mobileye.com>,
 "Thomas Petazzoni" <thomas.petazzoni@bootlin.com>, "Paolo Valerio"
 <pvalerio@redhat.com>
Subject: Re: [PATCH net-next v2 1/2] net: macb: implement
 ethtool_ops.get|set_channels()
Message-ID: <20260314075427.034097b2@kernel.org>
In-Reply-To: <DH1R3P9TTPS7.1YE0XC8RTNTIJ@bootlin.com>
References: <20260311-macb-set-channels-v2-0-982693a1f5fc@bootlin.com>
	<20260311-macb-set-channels-v2-1-982693a1f5fc@bootlin.com>
	<20260312182624.35ab61c8@kernel.org>
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On Fri, 13 Mar 2026 16:14:23 +0100 Th=C3=A9o Lebrun wrote:
> > should we reorder this with the running() check? =20
>=20
> I don't agree. For example when an operation is not supported, we start
> by checking that and returning EOPNOTSUPP. Then we validate the input
> data. Then we act.
>=20
> Here it is the same. When netif_running(), we never reply to any
> request even if it happens to be a no-op.
>=20
> I'll go ahead and send V3. Seeing how this was only a question I'll make
> the guess you don't care much about it and are fine either way.
> Same for me.

Sorry for the delay. This code can only be reached from the IOCTL path.
The Netlink path will check that params haven't changed in
ethnl_set_channels() (look at the @mod variable) and return 0 directly.
So you're basically adding a discrepancy between ioctl and Netlink.
Not a huge deal but I don't envy any user having to debug this..