Re: [PATCH 05/22] gpio: don't set label from irq helpers

[Linus Walleij <linus.walleij@xxxxxxxxxx>]

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

> From: Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxx>
>
> 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.
>
> Let's use the flags of the descriptor to figure out whether we should
> use the special "interrupt" label.
>
> Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxx>

I would refine the commit message: what you do IIUC is that you
simply avoid modifying a string, the label isn't set anymore,
instead a const string is returned and it is selected from the
state of an atomic variable (ha! smart!) and that is how the
atomicity is achieved.

Anyway:
Reviewed-by: Linus Walleij <linus.walleij@xxxxxxxxxx>

Yours,
Linus Walleij