atomics/arm: Define atomic64_fetch_add_unless()

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>
This commit is contained in:
Mark Rutland 2018-06-21 13:13:14 +01:00 committed by Ingo Molnar
parent ab0b910490
commit fee8ca9fa5

View File

@ -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))