gpio: nomadik: Add check for clk_enable()

[PATCH] gpio: nomadik: Add check for clk_enable()

Posted by Chenyuan Yang 8 months, 1 week ago

Add check for the return value of clk_enable() to catch
the potential error.

This is similar to the commit 8332e6670997
("spi: zynq-qspi: Add check for clk_enable()").

Signed-off-by: Chenyuan Yang <chenyuan0y@gmail.com>
Fixes: 966942ae4936 ("gpio: nomadik: extract GPIO platform driver from drivers/pinctrl/nomadik/")
---
 drivers/gpio/gpio-nomadik.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/gpio/gpio-nomadik.c b/drivers/gpio/gpio-nomadik.c
index fa19a44943fd..dbc4cdddf4df 100644
--- a/drivers/gpio/gpio-nomadik.c
+++ b/drivers/gpio/gpio-nomadik.c
@@ -262,8 +262,11 @@ static unsigned int nmk_gpio_irq_startup(struct irq_data *d)
 {
 	struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
 	struct nmk_gpio_chip *nmk_chip = gpiochip_get_data(gc);
+	int ret;
 
-	clk_enable(nmk_chip->clk);
+	ret = clk_enable(nmk_chip->clk);
+	if (ret)
+		return ret;
 	nmk_gpio_irq_unmask(d);
 	return 0;
 }
-- 
2.34.1

Re: [PATCH] gpio: nomadik: Add check for clk_enable()

Posted by Théo Lebrun 8 months, 1 week ago

Hello Chenyuan, Linus, Bartosz,

On Sat Apr 12, 2025 at 9:31 PM CEST, Chenyuan Yang wrote:
> Add check for the return value of clk_enable() to catch
> the potential error.
>
> This is similar to the commit 8332e6670997
> ("spi: zynq-qspi: Add check for clk_enable()").
>
> Signed-off-by: Chenyuan Yang <chenyuan0y@gmail.com>
> Fixes: 966942ae4936 ("gpio: nomadik: extract GPIO platform driver from drivers/pinctrl/nomadik/")
> ---
>  drivers/gpio/gpio-nomadik.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpio/gpio-nomadik.c b/drivers/gpio/gpio-nomadik.c
> index fa19a44943fd..dbc4cdddf4df 100644
> --- a/drivers/gpio/gpio-nomadik.c
> +++ b/drivers/gpio/gpio-nomadik.c
> @@ -262,8 +262,11 @@ static unsigned int nmk_gpio_irq_startup(struct irq_data *d)
>  {
>  	struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
>  	struct nmk_gpio_chip *nmk_chip = gpiochip_get_data(gc);
> +	int ret;
>  
> -	clk_enable(nmk_chip->clk);
> +	ret = clk_enable(nmk_chip->clk);
> +	if (ret)
> +		return ret;
>  	nmk_gpio_irq_unmask(d);
>  	return 0;
>  }

Returning a negative value whereas the ->irq_startup() [0] return value
is an unsigned int? From some quick godbolt testing and briefly reading
the spec it looks safe to do a round trip (signed->unsigned->signed),
though not ideal to my eyes.

The caller is __irq_startup() [1].

As for why irq_startup returns an unsigned int, I am unsure. The kernel
Git history isn't enough to know more. The startup field in struct
hw_interrupt_type appeared on v2.3.14 [2], so no commit message to
explain decisions.

Seeing the __irq_startup() code, my proposal would be to turn the return
value to a signed int, but I haven't exhaustively checked codepaths.

Thanks,

[0]: https://elixir.bootlin.com/linux/v6.13.7/source/include/linux/irq.h#L503
[1]: https://elixir.bootlin.com/linux/v6.13.7/source/kernel/irq/chip.c#L244
[2]: https://elixir.bootlin.com/linux/2.3.14/source/include/linux/irq.h#L21

--
Théo Lebrun, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

Re: [PATCH] gpio: nomadik: Add check for clk_enable()

Posted by Chenyuan Yang 8 months, 1 week ago

On Mon, Apr 14, 2025 at 4:24 AM Théo Lebrun <theo.lebrun@bootlin.com> wrote:
>
> Hello Chenyuan, Linus, Bartosz,
>
> On Sat Apr 12, 2025 at 9:31 PM CEST, Chenyuan Yang wrote:
> > Add check for the return value of clk_enable() to catch
> > the potential error.
> >
> > This is similar to the commit 8332e6670997
> > ("spi: zynq-qspi: Add check for clk_enable()").
> >
> > Signed-off-by: Chenyuan Yang <chenyuan0y@gmail.com>
> > Fixes: 966942ae4936 ("gpio: nomadik: extract GPIO platform driver from drivers/pinctrl/nomadik/")
> > ---
> >  drivers/gpio/gpio-nomadik.c | 5 ++++-
> >  1 file changed, 4 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpio/gpio-nomadik.c b/drivers/gpio/gpio-nomadik.c
> > index fa19a44943fd..dbc4cdddf4df 100644
> > --- a/drivers/gpio/gpio-nomadik.c
> > +++ b/drivers/gpio/gpio-nomadik.c
> > @@ -262,8 +262,11 @@ static unsigned int nmk_gpio_irq_startup(struct irq_data *d)
> >  {
> >       struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
> >       struct nmk_gpio_chip *nmk_chip = gpiochip_get_data(gc);
> > +     int ret;
> >
> > -     clk_enable(nmk_chip->clk);
> > +     ret = clk_enable(nmk_chip->clk);
> > +     if (ret)
> > +             return ret;
> >       nmk_gpio_irq_unmask(d);
> >       return 0;
> >  }
>
> Returning a negative value whereas the ->irq_startup() [0] return value
> is an unsigned int? From some quick godbolt testing and briefly reading
> the spec it looks safe to do a round trip (signed->unsigned->signed),
> though not ideal to my eyes.
>
> The caller is __irq_startup() [1].
>
> As for why irq_startup returns an unsigned int, I am unsure. The kernel
> Git history isn't enough to know more. The startup field in struct
> hw_interrupt_type appeared on v2.3.14 [2], so no commit message to
> explain decisions.
>
> Seeing the __irq_startup() code, my proposal would be to turn the return
> value to a signed int, but I haven't exhaustively checked codepaths.

Good catch! I agree that using a signed int could be a better option.

Dear Linus and Bartosz, could you please share your thoughts? If
you’re on board with the change, I’ll go ahead and send a new patch.

> Thanks,
>
> [0]: https://elixir.bootlin.com/linux/v6.13.7/source/include/linux/irq.h#L503
> [1]: https://elixir.bootlin.com/linux/v6.13.7/source/kernel/irq/chip.c#L244
> [2]: https://elixir.bootlin.com/linux/2.3.14/source/include/linux/irq.h#L21
>
> --
> Théo Lebrun, Bootlin
> Embedded Linux and Kernel engineering
> https://bootlin.com

-Chenyuan

Re: [PATCH] gpio: nomadik: Add check for clk_enable()

Posted by Linus Walleij 8 months, 1 week ago

On Mon, Apr 14, 2025 at 2:11 PM Chenyuan Yang <chenyuan0y@gmail.com> wrote:
> On Mon, Apr 14, 2025 at 4:24 AM Théo Lebrun <theo.lebrun@bootlin.com> wrote:

> > Seeing the __irq_startup() code, my proposal would be to turn the return
> > value to a signed int, but I haven't exhaustively checked codepaths.
>
> Good catch! I agree that using a signed int could be a better option.
>
> Dear Linus and Bartosz, could you please share your thoughts? If
> you’re on board with the change, I’ll go ahead and send a new patch.

Yeah that would be great, thanks!

Thanks for noticing this as well Theo, I think your team is the
most important user of this code right now.

Yours,
Linus Walleij

Re: [PATCH] gpio: nomadik: Add check for clk_enable()

Posted by Bartosz Golaszewski 8 months, 1 week ago

On Mon, Apr 14, 2025 at 2:11 PM Chenyuan Yang <chenyuan0y@gmail.com> wrote:
>
> On Mon, Apr 14, 2025 at 4:24 AM Théo Lebrun <theo.lebrun@bootlin.com> wrote:
> >
> > As for why irq_startup returns an unsigned int, I am unsure. The kernel
> > Git history isn't enough to know more. The startup field in struct
> > hw_interrupt_type appeared on v2.3.14 [2], so no commit message to
> > explain decisions.
> >
> > Seeing the __irq_startup() code, my proposal would be to turn the return
> > value to a signed int, but I haven't exhaustively checked codepaths.
>
> Good catch! I agree that using a signed int could be a better option.
>
> Dear Linus and Bartosz, could you please share your thoughts? If
> you’re on board with the change, I’ll go ahead and send a new patch.
>

Ok, I'm backing out this one then.

Bartosz

Re: [PATCH] gpio: nomadik: Add check for clk_enable()

Posted by Bartosz Golaszewski 8 months, 1 week ago

On Sat, 12 Apr 2025 14:31:53 -0500, Chenyuan Yang wrote:
> Add check for the return value of clk_enable() to catch
> the potential error.
> 
> This is similar to the commit 8332e6670997
> ("spi: zynq-qspi: Add check for clk_enable()").
> 
> 
> [...]

Applied, thanks!

[1/1] gpio: nomadik: Add check for clk_enable()
      https://git.kernel.org/brgl/linux/c/4521e0884c261fd286c02da942e9e8596bf2e7cf

Best regards,
-- 
Bartosz Golaszewski <brgl@bgdev.pl>

Re: [PATCH] gpio: nomadik: Add check for clk_enable()

Posted by Linus Walleij 8 months, 1 week ago

On Sat, Apr 12, 2025 at 9:31 PM Chenyuan Yang <chenyuan0y@gmail.com> wrote:

> Add check for the return value of clk_enable() to catch
> the potential error.
>
> This is similar to the commit 8332e6670997
> ("spi: zynq-qspi: Add check for clk_enable()").
>
> Signed-off-by: Chenyuan Yang <chenyuan0y@gmail.com>
> Fixes: 966942ae4936 ("gpio: nomadik: extract GPIO platform driver from drivers/pinctrl/nomadik/")

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>

Yours,
Linus Walleij