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Date: Tue, 17 Mar 2026 11:02:34 +0100
Message-Id: <DH4YZ4XEWDVH.25QOLQ4QJ4PXD@kernel.org>
Cc: "Andy Shevchenko" <andriy.shevchenko@linux.intel.com>, "Douglas
 Anderson" <dianders@chromium.org>, "Greg Kroah-Hartman"
 <gregkh@linuxfoundation.org>, "Rafael J . Wysocki" <rafael@kernel.org>,
 <stable@vger.kernel.org>, "Andrew Lunn" <andrew@lunn.ch>, "Daniel Scally"
 <djrscally@gmail.com>, "David S. Miller" <davem@davemloft.net>, "Eric
 Dumazet" <edumazet@google.com>, "Fabio Estevam" <festevam@gmail.com>,
 "Frank Li" <Frank.Li@nxp.com>, "Heikki Krogerus"
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 <lenb@kernel.org>, "Mark Brown" <broonie@kernel.org>, "Paolo Abeni"
 <pabeni@redhat.com>, "Pengutronix Kernel Team" <kernel@pengutronix.de>,
 "Rob Herring" <robh@kernel.org>, "Russell King" <linux@armlinux.org.uk>,
 "Sakari Ailus" <sakari.ailus@linux.intel.com>, "Saravana Kannan"
 <saravanak@kernel.org>, "Sascha Hauer" <s.hauer@pengutronix.de>,
 <devicetree@vger.kernel.org>, <driver-core@lists.linux.dev>,
 <imx@lists.linux.dev>, <linux-acpi@vger.kernel.org>,
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 <netdev@vger.kernel.org>
To: "Wolfram Sang" <wsa+renesas@sang-engineering.com>
From: "Danilo Krummrich" <dakr@kernel.org>
Subject: Re: [PATCH] device property: Make modifications of fwnode "flags"
 thread safe
References: <20260316154159.1.I0a4d03104ecd5103df3d76f66c8d21b1d15a2e38@changeid> <abkCPU3rxHI49N4_@shikoro> <abkD-VLprcbbEbB1@ashevche-desk.local> <abkF0GO01sMcOhvb@shikoro> <abkLEgrZbdb03VWg@ashevche-desk.local> <abkLY4AAQuFlTRC7@ashevche-desk.local> <abkT_jpjIki6pvX1@shikoro>
In-Reply-To: <abkT_jpjIki6pvX1@shikoro>

On Tue Mar 17, 2026 at 9:42 AM CET, Wolfram Sang wrote:
>
>> > What's the alignment for the u8 member in your SoC? 4 bytes or 8 bytes=
?
>> > (I assume it's 64-bit SoC.)
>>=20
>> FWIW, with the given change it will be still inside 64-byte data structu=
re
>> which most likely occupies a single cache line (before this patch and af=
ter
>> as well).
>
> I consider this directon of the discussion irrelevant. If the number is
> (maybe? That's to be discussed!) needlessly bigger than 0, then it
> doesn't matter how big the number is.
>
> Why don't you like the idea of taking the lock?

Which lock are we talking about, the device lock? If so, please not use it =
to
protect arbitrary other structures.