Re: [PATCH] gpio: Request interrupts after IRQ is initialized

[Shreeya Patel]

On 14/04/22 08:27, Mario Limonciello wrote:
> commit 5467801f1fcb ("gpio: Restrict usage of GPIO chip irq members before
> initialization") attempted to fix a race condition that lead to a NULL
> pointer, but in the process caused a regression for _AEI/_EVT declared
> GPIOs. This manifests in messages showing deferred probing while trying
> to allocate IRQs like so:
>
> [    0.688318] amd_gpio AMDI0030:00: Failed to translate GPIO pin 0x0000 to IRQ, err -517
> [    0.688337] amd_gpio AMDI0030:00: Failed to translate GPIO pin 0x002C to IRQ, err -517
> [    0.688348] amd_gpio AMDI0030:00: Failed to translate GPIO pin 0x003D to IRQ, err -517
> [    0.688359] amd_gpio AMDI0030:00: Failed to translate GPIO pin 0x003E to IRQ, err -517
> [    0.688369] amd_gpio AMDI0030:00: Failed to translate GPIO pin 0x003A to IRQ, err -517
> [    0.688379] amd_gpio AMDI0030:00: Failed to translate GPIO pin 0x003B to IRQ, err -517
> [    0.688389] amd_gpio AMDI0030:00: Failed to translate GPIO pin 0x0002 to IRQ, err -517
> [    0.688399] amd_gpio AMDI0030:00: Failed to translate GPIO pin 0x0011 to IRQ, err -517
> [    0.688410] amd_gpio AMDI0030:00: Failed to translate GPIO pin 0x0012 to IRQ, err -517
> [    0.688420] amd_gpio AMDI0030:00: Failed to translate GPIO pin 0x0007 to IRQ, err -517
>
> The code for walking _AEI doesn't handle deferred probing and so this leads
> to non-functional GPIO interrupts.
>
> Fix this issue by moving the call to `acpi_gpiochip_request_interrupts` to
> occur after gc->irc.initialized is set.


Thanks Mario for sending a fix for this issue, I didn't realize 
gpiod_to_irq() was also
being called through acpi_gpiochip_request_interrupts().
Change looks good to me.
Reviewed-by: Shreeya Patel <shreeya.patel@xxxxxxxxxxxxx>

> Cc: Shreeya Patel <shreeya.patel@xxxxxxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx
> Fixes: 5467801f1fcb ("gpio: Restrict usage of GPIO chip irq members before initialization")
> Reported-by: Mario Limonciello <mario.limonciello@xxxxxxx>
> Link: https://lore.kernel.org/linux-gpio/BL1PR12MB51577A77F000A008AA694675E2EF9@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/T/#u
> Signed-off-by: Mario Limonciello <mario.limonciello@xxxxxxx>
> ---
>   drivers/gpio/gpiolib.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
> index 085348e08986..b7694171655c 100644
> --- a/drivers/gpio/gpiolib.c
> +++ b/drivers/gpio/gpiolib.c
> @@ -1601,8 +1601,6 @@ static int gpiochip_add_irqchip(struct gpio_chip *gc,
>   
>   	gpiochip_set_irq_hooks(gc);
>   
> -	acpi_gpiochip_request_interrupts(gc);
> -
>   	/*
>   	 * Using barrier() here to prevent compiler from reordering
>   	 * gc->irq.initialized before initialization of above
> @@ -1612,6 +1610,8 @@ static int gpiochip_add_irqchip(struct gpio_chip *gc,
>   
>   	gc->irq.initialized = true;
>   
> +	acpi_gpiochip_request_interrupts(gc);
> +
>   	return 0;
>   }
>