linux-kernel - Re: [PATCH 00/22] gpio: rework locking and object life-time control

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Message-ID: <CACRpkdZrKGHiaQc5NVq5ceV=++SE3j7xEfwD9FBWRz0GCFpMCw@mail.gmail.com>
Date: Wed, 31 Jan 2024 21:32:10 +0100
From: Linus Walleij <linus.walleij@...aro.org>
To: Bartosz Golaszewski <brgl@...ev.pl>
Cc: Kent Gibson <warthog618@...il.com>, Alex Elder <elder@...aro.org>, 
	Geert Uytterhoeven <geert+renesas@...der.be>, "Paul E . McKenney" <paulmck@...nel.org>, 
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>, Wolfram Sang <wsa@...-dreams.de>, 
	linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Subject: Re: [PATCH 00/22] gpio: rework locking and object life-time control

On Tue, Jan 30, 2024 at 1:48 PM Bartosz Golaszewski <brgl@...ev.pl> wrote:

> We do NOT serialize all API callbacks. This means that provider callbacks
> may be called simultaneously and GPIO drivers need to provide their own
> locking if needed. This is on purpose. First: we only support exclusive
> GPIO usage[1] so there's no risk of two drivers getting in each other's
> way over the same GPIO. Second: with this series, we ensure enough
> consistency to limit the chance of drivers or user-space users crashing
> the kernel. With additional improvements in handling the flags field in
> GPIO descriptors there's very little to gain, while bitbanging drivers
> may care about the increased performance of going lockless.

OK I read this before but didn't understand it, now I understand it.

The series:
Reviewed-by: Linus Walleij <linus.walleij@...aro.org>

I think you should merge it all soon so we get some time to shake
it out in linux-next, hopefully any remaining bugs and cleanups
can be done in-tree.

Excellent work, by the way.

Yours,
Linus Walleij