linux-kernel - Re: [PATCH] ktime: Simplify ktime

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Date:   Fri, 26 May 2017 12:31:15 +0200 (CEST)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Mariusz Skamra <mariuszx.skamra@...el.com>
cc:     linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ktime: Simplify ktime_* comparison functions

On Fri, 26 May 2017, Mariusz Skamra wrote:
> -static inline int ktime_compare(const ktime_t cmp1, const ktime_t cmp2)
> -{
> -	if (cmp1 < cmp2)
> -		return -1;
> -	if (cmp1 > cmp2)
> -		return 1;
> -	return 0;
> -}
> +#define ktime_compare(cmp1, cmp2)	ktime_sub(cmp1, cmp2)

What's wrong with modifying the inline itself?

> -static inline bool ktime_after(const ktime_t cmp1, const ktime_t cmp2)
> -{
> -	return ktime_compare(cmp1, cmp2) > 0;
> -}
> +#define ktime_after(cmp1, cmp2)		(ktime_compare(cmp1, cmp2) > 0)

> -static inline bool ktime_before(const ktime_t cmp1, const ktime_t cmp2)
> -{
> -	return ktime_compare(cmp1, cmp2) < 0;
> -}
> +#define ktime_before(cmp1, cmp2)	(ktime_compare(cmp1, cmp2) < 0)

Sorry, but those two are just crap. That inline compiles to exactly the
same code as the macro. If not, yell at your compiler people.

Thanks,

	tglx