Re: [PATCH 1/2] jump_labels: Add API to deal with keys embedded in structures

[Marc Zyngier]

On 20/09/16 10:42, Peter Zijlstra wrote:
> On Mon, Sep 19, 2016 at 06:21:27PM +0100, Marc Zyngier wrote:
>> It is desirable to allow static keys to be integrated in structures,
>> as it can lead do slightly more readable code. But the current API
>> only provides DEFINE_STATIC_KEY_TRUE/FALSE, which is not exactly
>> nice and leads to the following idiom:
>>
>> 	static struct {
>> 		int			foo;
>> 		struct static_key_false	key;
>> 	} bar = {
>> 		.key	= STATIC_KEY_FALSE_INIT,
>> 	};
>>
>> 	[...]
>>
>> 	if (static_branch_unlikely(&bar.key))
>> 		foo = -1;
>>
>> which doesn't follow the recommended API, and uses the internals
>> of the static key implementation.
>>
>> This patch introduces DECLARE_STATIC_KEY_TRUE/FALSE, as well as
>> INIT_STATIC_KEY_TRUE/FALSE, which abstract such construct and
>> allow the internals to evolve without having to fix everything else:
>>
>> 	static struct {
>> 		int			 foo;
>> 		DECLARE_STATIC_KEY_FALSE(key);
>> 	} bar = {
>> 		INIT_STATIC_KEY_FALSE(.key),
>> 	};
> 
> Hurm..
> 
> I think I like the first better, it looks more like actual C. Either way
> around you need to now manually match up the type and initializer.

Fair enough, I'll stick to that for the KVM code.

Thanks for the quick feedback.

	M.
-- 
Jazz is not dead. It just smells funny...