linux-kernel - Re: [PATCH 02/22] gpio: of: assign and read the hog pointer atomically

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Message-ID: <CACRpkdYrBBiW4iv-ctEupfm=9xzy1x0fpxko=m2hDZriY=DeGA@mail.gmail.com>
Date: Wed, 31 Jan 2024 18:38:23 +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 02/22] gpio: of: assign and read the hog pointer atomically

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

> From: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
>
> The device nodes representing GPIO hogs cannot be deleted without
> unregistering the GPIO chip so there's no need to serialize their access.
> However we must ensure that users can get the right address so write and
> read it atomically.
>
> Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>

So this would give barriers around desc->hog, so we are talking
SMP where the same hogs are added and removed on different
CPUs here I suppose? Seems a bit theoretical but OK.
Reviewed-by: Linus Walleij <linus.walleij@...aro.org>

Yours,
Linus Walleij