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s390/percpu: implement this_cpu_xchg()
The generic variant has a local_irq_save/restore pair which is quite expensive. It is sufficient to disable preemption, which is a no-op with !CONFIG_PREEMPT and then use the regular xchg macro. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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@ -84,6 +84,24 @@ do { \
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#define this_cpu_cmpxchg_4(pcp, oval, nval) arch_this_cpu_cmpxchg(pcp, oval, nval)
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#define this_cpu_cmpxchg_8(pcp, oval, nval) arch_this_cpu_cmpxchg(pcp, oval, nval)
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#define arch_this_cpu_xchg(pcp, nval) \
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({ \
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typeof(pcp) *ptr__; \
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typeof(pcp) ret__; \
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preempt_disable(); \
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ptr__ = __this_cpu_ptr(&(pcp)); \
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ret__ = xchg(ptr__, nval); \
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preempt_enable(); \
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ret__; \
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})
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#define this_cpu_xchg_1(pcp, nval) arch_this_cpu_xchg(pcp, nval)
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#define this_cpu_xchg_2(pcp, nval) arch_this_cpu_xchg(pcp, nval)
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#define this_cpu_xchg_4(pcp, nval) arch_this_cpu_xchg(pcp, nval)
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#ifdef CONFIG_64BIT
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#define this_cpu_xchg_8(pcp, nval) arch_this_cpu_xchg(pcp, nval)
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#endif
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#include <asm-generic/percpu.h>
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#endif /* __ARCH_S390_PERCPU__ */
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