locking/atomics/alpha: Add smp_read_barrier_depends() to _release()/_relaxed() atomics
As part of the fight against smp_read_barrier_depends(), we require dependency ordering to be preserved when a dependency is headed by a load performed using an atomic operation. This patch adds smp_read_barrier_depends() to the _release() and _relaxed() atomics on alpha, which otherwise lack anything to enforce dependency ordering. Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1508840570-22169-6-git-send-email-will.deacon@arm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
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@ -13,6 +13,15 @@
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* than regular operations.
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*/
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/*
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* To ensure dependency ordering is preserved for the _relaxed and
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* _release atomics, an smp_read_barrier_depends() is unconditionally
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* inserted into the _relaxed variants, which are used to build the
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* barriered versions. To avoid redundant back-to-back fences, we can
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* define the _acquire and _fence versions explicitly.
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*/
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#define __atomic_op_acquire(op, args...) op##_relaxed(args)
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#define __atomic_op_fence __atomic_op_release
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#define ATOMIC_INIT(i) { (i) }
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#define ATOMIC64_INIT(i) { (i) }
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@ -60,6 +69,7 @@ static inline int atomic_##op##_return_relaxed(int i, atomic_t *v) \
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".previous" \
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:"=&r" (temp), "=m" (v->counter), "=&r" (result) \
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:"Ir" (i), "m" (v->counter) : "memory"); \
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smp_read_barrier_depends(); \
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return result; \
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}
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@ -77,6 +87,7 @@ static inline int atomic_fetch_##op##_relaxed(int i, atomic_t *v) \
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".previous" \
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:"=&r" (temp), "=m" (v->counter), "=&r" (result) \
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:"Ir" (i), "m" (v->counter) : "memory"); \
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smp_read_barrier_depends(); \
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return result; \
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}
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@ -111,6 +122,7 @@ static __inline__ long atomic64_##op##_return_relaxed(long i, atomic64_t * v) \
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".previous" \
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:"=&r" (temp), "=m" (v->counter), "=&r" (result) \
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:"Ir" (i), "m" (v->counter) : "memory"); \
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smp_read_barrier_depends(); \
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return result; \
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}
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@ -128,6 +140,7 @@ static __inline__ long atomic64_fetch_##op##_relaxed(long i, atomic64_t * v) \
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".previous" \
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:"=&r" (temp), "=m" (v->counter), "=&r" (result) \
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:"Ir" (i), "m" (v->counter) : "memory"); \
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smp_read_barrier_depends(); \
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return result; \
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}
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