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locking/atomic, arch/hexagon: 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: Richard Kuo <rkuo@codeaurora.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: linux-hexagon@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 0c074cbc33
commit 4be7dd3935
1 changed files with 28 additions and 5 deletions
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31
arch/hexagon/include/asm/atomic.h
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@ -127,16 +127,39 @@ static inline int atomic_##op##_return(int i, atomic_t *v) \
return output; \
}
#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) \
{ \
int output, val; \
\
__asm__ __volatile__ ( \
"1: %0 = memw_locked(%2);\n" \
" %1 = "#op "(%0,%3);\n" \
" memw_locked(%2,P3)=%1;\n" \
" if !P3 jump 1b;\n" \
: "=&r" (output), "=&r" (val) \
: "r" (&v->counter), "r" (i) \
: "memory", "p3" \
); \
return output; \
}
#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