linux-kernel - Re: [PATCH] spi: bcm2835: Do not call gpiod

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Message-ID: <CAMRc=Mefks5RMDkO-w-WT1279rKKyz8Up9UbuNdcF+WpsOxioA@mail.gmail.com>
Date: Wed, 2 Apr 2025 13:36:28 +0200
From: Bartosz Golaszewski <brgl@...ev.pl>
To: Florian Fainelli <florian.fainelli@...adcom.com>
Cc: linux-kernel@...r.kernel.org, Mark Brown <broonie@...nel.org>, 
	Ray Jui <rjui@...adcom.com>, Scott Branden <sbranden@...adcom.com>, 
	Broadcom internal kernel review list <bcm-kernel-feedback-list@...adcom.com>, 
	Linus Walleij <linus.walleij@...aro.org>, 
	Bartosz Golaszewski <bartosz.golaszewski@...aro.org>, 
	"open list:SPI SUBSYSTEM" <linux-spi@...r.kernel.org>, 
	"moderated list:BROADCOM BCM2711/BCM2835 ARM ARCHITECTURE" <linux-rpi-kernel@...ts.infradead.org>, 
	"moderated list:BROADCOM BCM2711/BCM2835 ARM ARCHITECTURE" <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH] spi: bcm2835: Do not call gpiod_put() on invalid descriptor

On Wed, Apr 2, 2025 at 12:43 AM Florian Fainelli
<florian.fainelli@...adcom.com> wrote:
>
> If we are unable to lookup the chip-select GPIO, the error path will
> call bcm2835_spi_cleanup() which unconditionally calls gpiod_put() on
> the cs->gpio variable which we just determined was invalid.
>
> Fixes: 21f252cd29f0 ("spi: bcm2835: reduce the abuse of the GPIO API")
> Signed-off-by: Florian Fainelli <florian.fainelli@...adcom.com>
> ---
>  drivers/spi/spi-bcm2835.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/spi/spi-bcm2835.c b/drivers/spi/spi-bcm2835.c
> index e1b9b1235787..a5d621b94d5e 100644
> --- a/drivers/spi/spi-bcm2835.c
> +++ b/drivers/spi/spi-bcm2835.c
> @@ -1162,7 +1162,8 @@ static void bcm2835_spi_cleanup(struct spi_device *spi)
>                                  sizeof(u32),
>                                  DMA_TO_DEVICE);
>
> -       gpiod_put(bs->cs_gpio);
> +       if (!IS_ERR(bs->cs_gpio))
> +               gpiod_put(bs->cs_gpio);
>         spi_set_csgpiod(spi, 0, NULL);
>
>         kfree(target);
> --
> 2.34.1
>
>

We could also just set it to NULL on error in bcm2835_spi_setup() but
I'm fine either way.

Reviewed-by: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>