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MIPS: barrier: Make __smp_mb__before_atomic() a no-op for Loongson3
Loongson3 systems with CONFIG_CPU_LOONGSON3_WORKAROUNDS enabled already
emit a full completion barrier as part of the inline assembly containing
LL/SC loops for atomic operations. As such the barrier emitted by
__smp_mb__before_atomic() is redundant, and we can remove it.
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: linux-mips@vger.kernel.org
Cc: Huacai Chen <chenhc@lemote.com>
Cc: Jiaxun Yang <jiaxun.yang@flygoat.com>
Cc: linux-kernel@vger.kernel.org
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arch/mips/include/asm/barrier.h
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arch/mips/include/asm/barrier.h
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#define nudge_writes() mb()
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#endif
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#define __smp_mb__before_atomic() __smp_mb__before_llsc()
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/*
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* In the Loongson3 LL/SC workaround case, all of our LL/SC loops already have
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* a completion barrier immediately preceding the LL instruction. Therefore we
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* can skip emitting a barrier from __smp_mb__before_atomic().
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*/
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#ifdef CONFIG_CPU_LOONGSON3_WORKAROUNDS
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# define __smp_mb__before_atomic()
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#else
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# define __smp_mb__before_atomic() __smp_mb__before_llsc()
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#endif
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#define __smp_mb__after_atomic() smp_llsc_mb()
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static inline void sync_ginv(void)