linux-kernel - Re: [PATCH 04/22] gpio: provide and use gpiod_get

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Message-ID: <CACRpkdZuGQ=9S=COdJRfaqzaC9ieGE8go7E7dcXfWX1XJdL_Rg@mail.gmail.com>
Date: Wed, 31 Jan 2024 20:36:02 +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 04/22] gpio: provide and use gpiod_get_label()

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

> From: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
>
> We will soon serialize access to the descriptor label using SRCU. The
> write-side of the protection will require calling synchronize_srcu()
> which must not be called from atomic context. We have two irq helpers:
> gpiochip_lock_as_irq() and gpiochip_unlock_as_irq() that set the label
> if the GPIO is not requested but is being used as interrupt. They are
> called with a spinlock held from the interrupt subsystem.
>
> They must not do it if we are to use SRCU so instead let's move the
> special corner case to a dedicated getter.
>
> First: let's implement and use the getter where it's applicable.
>
> Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>

After seeing the clever trick in the next patch I realized why
you do this.
Reviewed-by: Linus Walleij <linus.walleij@...aro.org>

Yours,
Linus Walleij