Re: [PATCHv2 05/16] atomics: prepare for atomic64_fetch_add_unless()

From: Peter Zijlstra <peterz@infradead.org>
To: Mark Rutland <mark.rutland@arm.com>
Cc: linux-kernel@vger.kernel.org, Boqun Feng <boqun.feng@gmail.com>,
	Will Deacon <will.deacon@arm.com>, Arnd Bergmann <arnd@arndb.de>,
	Richard Henderson <rth@twiddle.net>,
	Ivan Kokshaysky <ink@jurassic.park.msu.ru>,
	Matt Turner <mattst88@gmail.com>,
	Vineet Gupta <vgupta@synopsys.com>,
	Russell King <linux@armlinux.org.uk>,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Paul Mackerras <paulus@samba.org>,
	Michael Ellerman <mpe@ellerman.id.au>,
	Palmer Dabbelt <palmer@sifive.com>, Albert Ou <albert@sifive.com>
Subject: Re: [PATCHv2 05/16] atomics: prepare for atomic64_fetch_add_unless()
Date: Tue, 5 Jun 2018 11:26:37 +0200	[thread overview]
Message-ID: <20180605092637.GF12258@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20180529154346.3168-6-mark.rutland@arm.com>

On Tue, May 29, 2018 at 04:43:35PM +0100, Mark Rutland wrote:
>  /**
> + * atomic64_add_unless - add unless the number is already a given value
> + * @v: pointer of type atomic_t
> + * @a: the amount to add to v...
> + * @u: ...unless v is equal to u.
> + *
> + * Atomically adds @a to @v, so long as @v was not already @u.
> + * Returns non-zero if @v was not @u, and zero otherwise.

I always get confused by that wording; would something like: "Returns
true if the addition was done" not be more clear?

> + */
> +#ifdef atomic64_fetch_add_unless
> +static inline int atomic64_add_unless(atomic64_t *v, long long a, long long u)

Do we want to make that a "bool' return?

> +{
> +	return atomic64_fetch_add_unless(v, a, u) != u;
> +}
> +#endif