[Letux-kernel] BUG: drivers/pinctrl/core: races in pinctrl_groups and deferred probing
tony at atomide.com
Mon Jun 18 20:17:44 CEST 2018
* H. Nikolaus Schaller <hns at goldelico.com> [180618 16:46]:
> I can also demonstrate that the duplication has gone:
OK good to hear.
> And I was no longer able to reproduce the strcmp(NULL) issue. So it is either better hidden
> or gone.
It should not be possible with checks preventing registering
a group or function with no name. I'll try to repost the whole
series tomorrow with that added.
> So code just needs group cleanup on failed probing and fixing the mutex around pinctrl_generic_add_group().
> I think we need the mutex because a race still can happen when create_pinctrl() is calling pcs_dt_node_to_map()
> and pinctrl_generic_add_group() w/o being locked on pinctrl_maps_mutex.
> The race I suspect is that two drivers are trying to insert the same name and may come
> both to the conclusion that it does not yet exist. And both insert into the radix tree.
> The window of risk is small though... It is in pinctrl_generic_add_group() between calling
> pinctrl_generic_group_name_to_selector() and radix_tree_insert() so we probably won't
> see it in real hardware tests.
Hmm but that race should be already fixed with mutex held
by the pin controller drivers with these fixes? Or am I
missing something still?
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