linux-kernel - Re: [PATCH 0/3] Revert "revocable: Revocable resource management"

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Message-ID: <aXneX-aZofvuk8gl@ninjato>
Date: Wed, 28 Jan 2026 11:01:03 +0100
From: Wolfram Sang <wsa+renesas@...g-engineering.com>
To: Bartosz Golaszewski <brgl@...nel.org>
Cc: Jason Gunthorpe <jgg@...dia.com>, Johan Hovold <johan@...nel.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Danilo Krummrich <dakr@...nel.org>,
	"Rafael J . Wysocki" <rafael@...nel.org>,
	Tzung-Bi Shih <tzungbi@...nel.org>,
	Linus Walleij <linusw@...nel.org>, Jonathan Corbet <corbet@....net>,
	Shuah Khan <shuah@...nel.org>,
	Laurent Pinchart <laurent.pinchart@...asonboard.com>,
	Simona Vetter <simona.vetter@...ll.ch>,
	Dan Williams <dan.j.williams@...el.com>, linux-doc@...r.kernel.org,
	linux-kselftest@...r.kernel.org, linux-kernel@...r.kernel.org,
	Bartosz Golaszewski <bartosz.golaszewski@....qualcomm.com>
Subject: Re: [PATCH 0/3] Revert "revocable: Revocable resource management"

> One exception is I2C where the logic is so broken we need to first
> rework a lot of drivers.

Let's say "bitrotten" instead of broken. People used what was available
at that time and they prevented the kernel from crashing, at least. And
up to now, nobody had the bandwidth to improve that part in I2C.

> Wolfram is on board with that though.

Ack. I want to emphasize here that for I2C the SRCU part goes into the
subsystem, not into the drivers.

(Disclaimer: I don't have the time to even read all the mails discussing
'revocable' despite it maybe being used in I2C. I am busy enough
handling the preparations needed to improve the I2C core to handle the
lifecycle issues. If 'revocable' is the final piece or not is a second
step for me. Maybe even a third.)

> > The reason cdev keeps coming up is because there are few common ways a
> > typical driver can actually generate concurrent operations during and
> > after remove that would be problematic.

Let me point out again that Dan Williams already had a PoC-patch for
handling the cdev issue generically [1]. Dunno if this fact is present
in the current discussion.

[1] https://lkml.org/lkml/2021/1/20/999

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