Hi,
On Wednesday 11 November 2015 14:36:53 Vladimir Zapolskiy wrote:
> Commit c0017ed71966 ("gpio: Introduce gpio descriptor 'name'") causes
> OOPS on boot on LPC32xx boards:
>
> Unable to handle kernel NULL pointer dereference at virtual address 00000000
> CPU: 0 PID: 1 Comm: swapper Not tainted 4.3.0+ #707
> Hardware name: LPC32XX SoC (Flattened Device Tree)
> task: c381baa0 ti: c381e000 task.ti: c381e000
> PC is at strcmp+0x10/0x40
> LR is at gpiochip_add+0x3d0/0x4d4
> pc : [<>] lr : [<>] psr: a0000093
> sp : c381fd60 ip : c381fd70 fp : c381fd6c
>
> [snip]
>
> Backtrace:
> [<>] (strcmp) from [<>] (gpiochip_add+0x3d0/0x4d4)
> [<>] (gpiochip_add) from [<>] (lpc32xx_gpio_probe+0x44/0x60)
> [<>] (lpc32xx_gpio_probe) from [<>] (platform_drv_probe+0x40/0x8c)
> [<>] (platform_drv_probe) from [<>] (driver_probe_device+0x110/0x294)
> [<>] (driver_probe_device) from [<>] (__driver_attach+0x70/0x94)
> [<>] (__driver_attach) from [<>] (bus_for_each_dev+0x74/0x98)
> [<>] (bus_for_each_dev) from [<>] (driver_attach+0x20/0x28)
> [<>] (driver_attach) from [<>] (bus_add_driver+0xd4/0x1f0)
> [<>] (bus_add_driver) from [<>] (driver_register+0xa4/0xe8)
> [<>] (driver_register) from [<>] (__platform_driver_register+0x38/0x4c)
> [<>] (__platform_driver_register) from [<>] (lpc32xx_gpio_driver_init+0x18/0x20)
> [<>] (lpc32xx_gpio_driver_init) from [<>] (do_one_initcall+0x108/0x1c8)
> [<>] (do_one_initcall) from [<>] (kernel_init_freeable+0x10c/0x1d4)
> [<>] (kernel_init_freeable) from [<>] (kernel_init+0x10/0xec)
> [<>] (kernel_init) from [<>] (ret_from_fork+0x14/0x24)
>
> This is caused by the fact that at the moment some GPIO names are set
> to NULL, there is a hole in linear representation of one GPI bank, see
> drivers/gpio/gpio-lpc32xx.c / gpi_p3_names[] for details.
>
> The same problem most probably affects also gpio-cs5535.c, see
> cs5535_gpio_names[].
>
> Signed-off-by: Vladimir Zapolskiy <vz@xxxxxxxxx>
> ---
> Linus, Markus,
>
> I understand that LPC32xx GPIO driver is ugly (hopefully this
> will be changed in future), but please account this problem.
>
> I don't ask for inclusion of this change, because my own analysis is
> not done completely.
>
> Also please review, the same problem probably affects gpio-cs5535.c
> as well, see cs5535_gpio_names[].
Thanks for this hint. But I think these patches for gpio_name_to_desc won't get
mainline any time soon as this depends on the chardev interface and how it will
look like.
Best Regards,
Markus
>
> drivers/gpio/gpiolib.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
> index a18f00f..2a91f32 100644
> --- a/drivers/gpio/gpiolib.c
> +++ b/drivers/gpio/gpiolib.c
> @@ -233,7 +233,7 @@ static struct gpio_desc *gpio_name_to_desc(const char * const name)
> for (i = 0; i != chip->ngpio; ++i) {
> struct gpio_desc *gpio = &chip->desc[i];
>
> - if (!gpio->name)
> + if (!gpio->name || !name)
> continue;
>
> if (!strcmp(gpio->name, name)) {
>
--
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