atomics/arm: Define atomic64_fetch_add_unless() (fee8ca9f) · Commits · 戴 / test

As a step towards unifying the atomic/atomic64/atomic_long APIs, this patch converts the arch/arm implementation of atomic64_add_unless() into an implementation of atomic64_fetch_add_unless(). A wrapper in <linux/atomic.h> will build atomic_add_unless() atop of this, provided it is given a preprocessor definition. No functional change is intended as a result of this patch. Signed-off-by:

Mark Rutland <mark.rutland@arm.com> Reviewed-by:

Will Deacon <will.deacon@arm.com> Acked-by:

Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Russell King <linux@armlinux.org.uk> Cc: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/lkml/20180621121321.4761-12-mark.rutland@arm.com Signed-off-by:

Ingo Molnar <mingo@kernel.org>

arch/arm/include/asm/atomic.h

+10 −10

Original line number	Diff line number	Diff line
		@@ -486,11 +486,11 @@ static inline long long atomic64_dec_if_positive(atomic64_t *v)
		return result;
		}

		static inline int atomic64_add_unless(atomic64_t *v, long long a, long long u)
		static inline long long atomic64_fetch_add_unless(atomic64_t *v, long long a,
		long long u)
		{
		long long val;
		long long oldval, newval;
		unsigned long tmp;
		int ret = 1;

		smp_mb();
		prefetchw(&v->counter);
		@@ -499,23 +499,23 @@ static inline int atomic64_add_unless(atomic64_t *v, long long a, long long u)
		"1: ldrexd %0, %H0, [%4]\n"
		" teq %0, %5\n"
		" teqeq %H0, %H5\n"
		" moveq %1, #0\n"
		" beq 2f\n"
		" adds %Q0, %Q0, %Q6\n"
		" adc %R0, %R0, %R6\n"
		" strexd %2, %0, %H0, [%4]\n"
		" adds %Q1, %Q0, %Q6\n"
		" adc %R1, %R0, %R6\n"
		" strexd %2, %1, %H1, [%4]\n"
		" teq %2, #0\n"
		" bne 1b\n"
		"2:"
		: "=&r" (val), "+r" (ret), "=&r" (tmp), "+Qo" (v->counter)
		: "=&r" (oldval), "=&r" (newval), "=&r" (tmp), "+Qo" (v->counter)
		: "r" (&v->counter), "r" (u), "r" (a)
		: "cc");

		if (ret)
		if (oldval != u)
		smp_mb();

		return ret;
		return oldval;
		}
		#define atomic64_fetch_add_unless atomic64_fetch_add_unless

		#define atomic64_add_negative(a, v) (atomic64_add_return((a), (v)) < 0)
		#define atomic64_inc(v) atomic64_add(1LL, (v))

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