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

From: Grygorii Strashko <grygorii.strashko@ti.com>
To: Lars-Peter Clausen <lars@metafoo.de>,
	Linus Walleij <linus.walleij@linaro.org>
Cc: Alexandre Courbot <gnurou@gmail.com>,
	Linux-OMAP <linux-omap@vger.kernel.org>,
	"linux-gpio@vger.kernel.org" <linux-gpio@vger.kernel.org>,
	Sekhar Nori <nsekhar@ti.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Geert Uytterhoeven <geert@linux-m68k.org>,
	Roger Quadros <rogerq@ti.com>
Subject: Re: [PATCH] gpiolib: irqchip: use different lockdep class for each gpio irqchip
Date: Fri, 14 Aug 2015 16:05:52 +0300	[thread overview]
Message-ID: <55CDE7B0.5040108@ti.com> (raw)
In-Reply-To: <55CDE1BB.1060708@metafoo.de>

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] https://lkml.org/lkml/2015/6/25/144
> [2] https://lkml.org/lkml/2015/7/8/43

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

-- 
regards,
-grygorii