On Fri, 2017-07-14 at 14:07 +0200, Arnd Bergmann wrote:
> gcc-7 notices that the pin_table is an array of 16-bit numbers,
> but we assume it can be printed as a two-character hexadecimal
> string:
>
> drivers/gpio/gpiolib-acpi.c: In function
> 'acpi_gpiochip_request_interrupt':
> drivers/gpio/gpiolib-acpi.c:206:24: warning: '%02X' directive writing
> between 2 and 4 bytes into a region of size 3 [-Wformat-overflow=]
> sprintf(ev_name, "_%c%02X",
> ^~~~
> drivers/gpio/gpiolib-acpi.c:206:20: note: directive argument in the
> range [0, 65535]
> sprintf(ev_name, "_%c%02X",
> ^~~~~~~~~
> drivers/gpio/gpiolib-acpi.c:206:3: note: 'sprintf' output between 5
> and 7 bytes into a destination of size 5
> sprintf(ev_name, "_%c%02X",
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~
> agpio->triggering == ACPI_EDGE_SENSITIVE ? 'E' : 'L',
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> pin);
> ~~~~
This is obviously a false positive warning.
Here we have
int pin = u16 pin_table[0] <= 255 (implying >= 0).
I see few options how to make it more clear
1) your proposal;
2) use "%02hhX" instead;
3) use if (ret >= 0 && ret <= 255) condition.
I would choose one of the 2-3.
In case gcc will complain about 3), file a bug to gcc crazy warning.
>
> This can't be right, so this changes it to truncate the number to
> an 8-bit pin number.
>
> Fixes: 0d1c28a449c6 ("gpiolib-acpi: Add ACPI5 event model support to
> gpio.")
> Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
> ---
> drivers/gpio/gpiolib-acpi.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpio/gpiolib-acpi.c b/drivers/gpio/gpiolib-acpi.c
> index c9b42dd12dfa..c3faea724af8 100644
> --- a/drivers/gpio/gpiolib-acpi.c
> +++ b/drivers/gpio/gpiolib-acpi.c
> @@ -205,7 +205,7 @@ static acpi_status
> acpi_gpiochip_request_interrupt(struct acpi_resource *ares,
> char ev_name[5];
> sprintf(ev_name, "_%c%02X",
> agpio->triggering == ACPI_EDGE_SENSITIVE ?
> 'E' : 'L',
> - pin);
> + (u8)pin);
> if (ACPI_SUCCESS(acpi_get_handle(handle, ev_name,
> &evt_handle)))
> handler = acpi_gpio_irq_handler;
> }
--
Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Intel Finland Oy
