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locking/atomic, arch/m32r: Implement atomic_fetch_{add,sub,and,or,xor}() 

Implement FETCH-OP atomic primitives, these are very similar to the
existing OP-RETURN primitives we already have, except they return the
value of the atomic variable _before_ modification.

This is especially useful for irreversible operations -- such as
bitops (because it becomes impossible to reconstruct the state prior
to modification).

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Peter Zijlstra 2016-04-18 01:16:07 +02:00 committed by Ingo Molnar
parent cc102507fa
commit f649370523
1 changed files with 34 additions and 4 deletions
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38
arch/m32r/include/asm/atomic.h
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@ -89,16 +89,46 @@ static __inline__ int atomic_##op##_return(int i, atomic_t *v) \
return result; \
}
#define ATOMIC_OPS(op) ATOMIC_OP(op) ATOMIC_OP_RETURN(op)
#define ATOMIC_FETCH_OP(op) \
static __inline__ int atomic_fetch_##op(int i, atomic_t *v) \
{ \
unsigned long flags; \
int result, val; \
\
local_irq_save(flags); \
__asm__ __volatile__ ( \
"# atomic_fetch_" #op " \n\t" \
DCACHE_CLEAR("%0", "r4", "%2") \
M32R_LOCK" %1, @%2; \n\t" \
"mv %0, %1 \n\t" \
#op " %1, %3; \n\t" \
M32R_UNLOCK" %1, @%2; \n\t" \
: "=&r" (result), "=&r" (val) \
: "r" (&v->counter), "r" (i) \
: "memory" \
__ATOMIC_CLOBBER \
); \
local_irq_restore(flags); \
\
return result; \
}
#define ATOMIC_OPS(op) ATOMIC_OP(op) ATOMIC_OP_RETURN(op) ATOMIC_FETCH_OP(op)
ATOMIC_OPS(add)
ATOMIC_OPS(sub)
ATOMIC_OP(and)
ATOMIC_OP(or)
ATOMIC_OP(xor)
#undef ATOMIC_OPS
#define ATOMIC_OPS(op) ATOMIC_OP(op) ATOMIC_FETCH_OP(op)
#define atomic_fetch_or atomic_fetch_or
ATOMIC_OPS(and)
ATOMIC_OPS(or)
ATOMIC_OPS(xor)
#undef ATOMIC_OPS
#undef ATOMIC_FETCH_OP
#undef ATOMIC_OP_RETURN
#undef ATOMIC_OP