Commit b3a2a05f authored by Mark Rutland's avatar Mark Rutland Committed by Ingo Molnar
Browse files

atomics/treewide: Make conditional inc/dec ops optional 



The conditional inc/dec ops differ for atomic_t and atomic64_t:

- atomic_inc_unless_positive() is optional for atomic_t, and doesn't exist for atomic64_t.
- atomic_dec_unless_negative() is optional for atomic_t, and doesn't exist for atomic64_t.
- atomic_dec_if_positive is optional for atomic_t, and is mandatory for atomic64_t.

Let's make these consistently optional for both. At the same time, let's
clean up the existing fallbacks to use atomic_try_cmpxchg().

The instrumented atomics are updated accordingly.

There should be no functional change as a result of this patch.

Signed-off-by: default avatarMark Rutland <mark.rutland@arm.com>
Reviewed-by: default avatarWill Deacon <will.deacon@arm.com>
Acked-by: default avatarPeter 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/20180621121321.4761-18-mark.rutland@arm.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 9837559d

arch/alpha/include/asm/atomic.h

+1 −0
Original line number Diff line number Diff line
@@ -296,5 +296,6 @@ static inline long atomic64_dec_if_positive(atomic64_t *v) 
	smp_mb();

	return old - 1;

}

#define atomic64_dec_if_positive atomic64_dec_if_positive



#endif /* _ALPHA_ATOMIC_H */

arch/arc/include/asm/atomic.h

+1 −0
Original line number Diff line number Diff line
@@ -517,6 +517,7 @@ static inline long long atomic64_dec_if_positive(atomic64_t *v) 


	return val;

}

#define atomic64_dec_if_positive atomic64_dec_if_positive



/**

 * atomic64_fetch_add_unless - add unless the number is a given value

arch/arm/include/asm/atomic.h

+1 −0
Original line number Diff line number Diff line
@@ -474,6 +474,7 @@ static inline long long atomic64_dec_if_positive(atomic64_t *v) 


	return result;

}

#define atomic64_dec_if_positive atomic64_dec_if_positive



static inline long long atomic64_fetch_add_unless(atomic64_t *v, long long a,

						  long long u)

arch/arm64/include/asm/atomic.h

+2 −0
Original line number Diff line number Diff line
@@ -159,5 +159,7 @@ 


#define atomic64_andnot			atomic64_andnot



#define atomic64_dec_if_positive	atomic64_dec_if_positive



#endif

#endif

arch/ia64/include/asm/atomic.h

+0 −16
Original line number Diff line number Diff line
@@ -215,22 +215,6 @@ ATOMIC64_FETCH_OP(xor, ^) 
	(cmpxchg(&((v)->counter), old, new))

#define atomic64_xchg(v, new) (xchg(&((v)->counter), new))



static __inline__ long atomic64_dec_if_positive(atomic64_t *v)

{

	long c, old, dec;

	c = atomic64_read(v);

	for (;;) {

		dec = c - 1;

		if (unlikely(dec < 0))

			break;

		old = atomic64_cmpxchg((v), c, dec);

		if (likely(old == c))

			break;

		c = old;

	}

	return dec;

}



#define atomic_add(i,v)			(void)atomic_add_return((i), (v))

#define atomic_sub(i,v)			(void)atomic_sub_return((i), (v))

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