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atomics/generic: Define atomic64_fetch_add_unless()

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As a step towards unifying the atomic/atomic64/atomic_long APIs, this
patch converts the generic implementation of atomic64_add_unless() into
a generic 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: Arnd Bergmann <arnd@arndb.de>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/lkml/20180621121321.4761-9-mark.rutland@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Mark Rutland
2018-06-21 13:13:11 +01:00
committed by Ingo Molnar
parent 0ae1d99402
commit 00b808ab79
2 changed files with 9 additions and 8 deletions
Download Patch File Download Diff File Expand all files Collapse all files

3
include/asm-generic/atomic64.h
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@@ -53,7 +53,8 @@ ATOMIC64_OPS(xor)
extern long long atomic64_dec_if_positive(atomic64_t *v); extern long long atomic64_dec_if_positive(atomic64_t *v);
extern long long atomic64_cmpxchg(atomic64_t *v, long long o, long long n); extern long long atomic64_cmpxchg(atomic64_t *v, long long o, long long n);
extern long long atomic64_xchg(atomic64_t *v, long long new); extern long long atomic64_xchg(atomic64_t *v, long long new);
extern bool atomic64_add_unless(atomic64_t *v, long long a, long long u); extern long long atomic64_fetch_add_unless(atomic64_t *v, long long a, long long u);
#define atomic64_fetch_add_unless atomic64_fetch_add_unless
#define atomic64_add_negative(a, v) (atomic64_add_return((a), (v)) < 0) #define atomic64_add_negative(a, v) (atomic64_add_return((a), (v)) < 0)
#define atomic64_inc(v) atomic64_add(1LL, (v)) #define atomic64_inc(v) atomic64_add(1LL, (v))

14
lib/atomic64.c
View File

@@ -178,18 +178,18 @@ long long atomic64_xchg(atomic64_t *v, long long new)
} }
EXPORT_SYMBOL(atomic64_xchg); EXPORT_SYMBOL(atomic64_xchg);
bool atomic64_add_unless(atomic64_t *v, long long a, long long u) long long atomic64_fetch_add_unless(atomic64_t *v, long long a, long long u)
{ {
unsigned long flags; unsigned long flags;
raw_spinlock_t *lock = lock_addr(v); raw_spinlock_t *lock = lock_addr(v);
bool ret = false; long long val;
raw_spin_lock_irqsave(lock, flags); raw_spin_lock_irqsave(lock, flags);
if (v->counter != u) { val = v->counter;
if (val != u)
v->counter += a; v->counter += a;
ret = true;
}
raw_spin_unlock_irqrestore(lock, flags); raw_spin_unlock_irqrestore(lock, flags);
return ret;
return val;
} }
EXPORT_SYMBOL(atomic64_add_unless); EXPORT_SYMBOL(atomic64_fetch_add_unless);