Re: [PATCH] gpiolib: irqchip: use different lockdep class for each gpio irqchip

From: Grygorii Strashko
Date: Fri Aug 14 2015 - 09:06:09 EST

On 08/14/2015 03:40 PM, Lars-Peter Clausen wrote:
> On 08/14/2015 02:34 PM, Linus Walleij wrote:
> [...]
>> Every chip will get their own lock class on the heap.
>> But I think it is a bit kludgy.
>> Is it not possible to have the lock key in struct gpio_chip
>> be a real member instead of a pointer and get a per-chip
>> lock that way?
>> (...)
>> struct lock_class_key lock_key;
>> instead of:
>> struct lock_class_key *lock_key;
>> -> problem solved, without kludgy header defines?
> Lock keys need to be in persistent memory since they have a unlimited life
> time. Once registered it is expected to exist until the system is reset.
> We recently fixed the same issue of nested locks in regmap. For reference
> the discussion with had a look at different ways to solve this can be found
> here[1] and the final patch series that went in here[2].
> - Lars
> [1]
> [2]

I've actually followed [2], but without deep digging in Lock keys anatomy :)
(as mentioned in commit message)

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