linux-kernel - Re: [PATCH v5 5/7] revocable: Add fops replacement

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Message-ID: <20251017163738.GB316284@nvidia.com>
Date: Fri, 17 Oct 2025 13:37:38 -0300
From: Jason Gunthorpe <jgg@...dia.com>
To: Danilo Krummrich <dakr@...nel.org>
Cc: Tzung-Bi Shih <tzungbi@...nel.org>, Benson Leung <bleung@...omium.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	"Rafael J . Wysocki" <rafael@...nel.org>,
	Jonathan Corbet <corbet@....net>, Shuah Khan <shuah@...nel.org>,
	linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
	chrome-platform@...ts.linux.dev, linux-kselftest@...r.kernel.org,
	Laurent Pinchart <laurent.pinchart@...asonboard.com>,
	Bartosz Golaszewski <brgl@...ev.pl>,
	Wolfram Sang <wsa+renesas@...g-engineering.com>,
	Simona Vetter <simona.vetter@...ll.ch>,
	Dan Williams <dan.j.williams@...el.com>
Subject: Re: [PATCH v5 5/7] revocable: Add fops replacement

On Fri, Oct 17, 2025 at 06:29:10PM +0200, Danilo Krummrich wrote:

> I'm not sure about MISC device though. Unless there's a good reason,
> I think MISC device should be "fenced" instead.

misc is a very small wrapper around raw fops, and raw fops are
optimized for performance. Adding locking that many important things
like normal files don't need to all fops would not be agreed.

The sketch in this series where we have a core helper to provide a
shim fops that adds on the lock is smart and I think could be an
agreeable way to make a synchronous misc and cdev unregister for
everyone to trivially use.

Jason