[Letux-kernel] BUG: drivers/pinctrl/core: races in pinctrl_groups and deferred probing

[H. Nikolaus Schaller]

Hi Tony,

> Am 14.06.2018 um 14:01 schrieb Tony Lindgren <tony at atomide.com>:
> 
> * H. Nikolaus Schaller <hns at goldelico.com> [180613 12:41]:
>> 
>> Now if I look into pinctrl_generic_add_group() and pinctrl_generic_get_group_name(),
>> pctldev->num_groups++ is not protected if pinctrl_generic_add_group() may be called by
>> two threads in parallel for the same pctldev. Hence a second thread may try to insert
>> a different node into the radix tree at the same selector index. This fails but there
>> is no error check - and the second entry is completely missing (but probably assumed to
>> be there).
> 
> Sounds like pinctrl-single.c is missing mutex around calls to
> pinctrl_generic_add_group()?

Yes, that could be. I didn't research the call path, just the one of
devm_pinctrl_get(). That uses a mutex in

https://elixir.bootlin.com/linux/v4.17.1/source/drivers/pinctrl/core.c#L1021

Maybe a similar mutex is missing elsewhere.

BR,
Nikolaus