Re: [PATCH] pinctrl: imx: reset group index on probe

From: Vladimir Zapolskiy
Date: Tue Oct 18 2016 - 18:40:21 EST

Hi Stefan,

On 19.10.2016 00:09, Stefan Agner wrote:
> Group index is incremented on every new group parsed. Since the
> field is part of struct imx_pinctrl_soc_info, which is typically
> a global variable passed by the individual pinctrl-imx.c based
> driver, it does not get cleared automatically when re-probing the
> driver. This lead imx_pinctrl_parse_functions passing a group
> pointer which is outside of the allocated group space on second
> probe and onwards. Typically this ended up in a NULL pointer
> dereference when accessing the name field like this:
> Unable to handle kernel NULL pointer dereference at virtual address 00000000
> ...
> PC is at strcmp+0x18/0x44
> LR is at imx_dt_node_to_map+0xc4/0x290
> Avoid this by setting group_index to 0 on probe.
> This has been observed when using DEBUG_TEST_DRIVER_REMOVE.
> Signed-off-by: Stefan Agner <stefan@xxxxxxxx>

I've recently developed a pinctrl driver for the last remaining
i.MX31 platform from the SoC series (not published yet), it does
not fit well under any of the 3 existing drivers, and instead
of adding 1.5K lines of code with half of them almost copy-pasted
from the rest drivers I started to work on generalization of the
i.MX/Vybrid pinctrl/pinmux drivers.

This task is large and I'm not sure when I complete and share
the results, but your change conflicts with one of the changes
in my backlog... Let me share it with you right now, because it
deals with info->group_index from another point of view and it
(unlikely) may have an impact on Vybrid platform, which I can not

> ---
> drivers/pinctrl/freescale/pinctrl-imx.c | 1 +
> 1 file changed, 1 insertion(+)
> diff --git a/drivers/pinctrl/freescale/pinctrl-imx.c b/drivers/pinctrl/freescale/pinctrl-imx.c
> index 4761320..79c4e14 100644
> --- a/drivers/pinctrl/freescale/pinctrl-imx.c
> +++ b/drivers/pinctrl/freescale/pinctrl-imx.c
> @@ -687,6 +687,7 @@ static int imx_pinctrl_probe_dt(struct platform_device *pdev,
> if (!info->functions)
> return -ENOMEM;
> + info->group_index = 0;
> if (flat_funcs) {
> info->ngroups = of_get_child_count(np);
> } else {

With best wishes,