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atomics/treewide: Make atomic64_fetch_add_unless() optional

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Architectures with atomic64_fetch_add_unless() provide a preprocessor
symbol if they do so, and all other architectures have trivial C
implementations of atomic64_add_unless() which are near-identical.

Let's unify the trivial definitions of atomic64_fetch_add_unless() in
<linux/atomic.h>, so that we always have both
atomic64_fetch_add_unless() and atomic64_add_unless() with less
boilerplate code.

This means that atomic64_add_unless() is always implemented in core
code, and the instrumented atomics are updated accordingly.

There should be no functional change 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: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/lkml/20180621121321.4761-15-mark.rutland@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Mark Rutland
2018-06-21 13:13:17 +01:00
committed by Ingo Molnar
parent 2b523f170e
commit 356701329f
9 changed files with 24 additions and 133 deletions
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26
include/linux/atomic.h
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@@ -1042,6 +1042,30 @@ static inline int atomic_dec_if_positive(atomic_t *v)
#define atomic64_try_cmpxchg_release atomic64_try_cmpxchg
#endif /* atomic64_try_cmpxchg */
/**
* atomic64_fetch_add_unless - add unless the number is already a given value
* @v: pointer of type atomic64_t
* @a: the amount to add to v...
* @u: ...unless v is equal to u.
*
* Atomically adds @a to @v, if @v was not already @u.
* Returns the original value of @v.
*/
#ifndef atomic64_fetch_add_unless
static inline long long atomic64_fetch_add_unless(atomic64_t *v, long long a,
long long u)
{
long long c = atomic64_read(v);
do {
if (unlikely(c == u))
break;
} while (!atomic64_try_cmpxchg(v, &c, c + a));
return c;
}
#endif
/**
* atomic64_add_unless - add unless the number is already a given value
* @v: pointer of type atomic_t
@@ -1051,12 +1075,10 @@ static inline int atomic_dec_if_positive(atomic_t *v)
* Atomically adds @a to @v, if @v was not already @u.
* Returns true if the addition was done.
*/
#ifdef atomic64_fetch_add_unless
static inline bool atomic64_add_unless(atomic64_t *v, long long a, long long u)
{
return atomic64_fetch_add_unless(v, a, u) != u;
}
#endif
/**
* atomic64_inc_not_zero - increment unless the number is zero