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Commit 4c2241fd authored by Heiko Carstens's avatar Heiko Carstens Committed by Martin Schwidefsky
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[S390] percpu: implement arch specific irqsafe_cpu_ops 



Implement arch specific irqsafe_cpu ops. The arch specific ops do not
disable/enable interrupts since that is an expensive operation. Instead
we disable preemption and perform a compare and swap loop.
Since on server distros (the ones we care about) preemption is disabled
the preempt_disable()/preempt_enable() pair is a nop.
In the end this code should be faster than the generic one.

Signed-off-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent add7490c

arch/s390/include/asm/cmpxchg.h

+0 −1
Original line number Diff line number Diff line
@@ -167,7 +167,6 @@ static inline unsigned long __cmpxchg(void *ptr, unsigned long old, 
#ifdef CONFIG_64BIT

#define cmpxchg64(ptr, o, n)						\

({									\

	BUILD_BUG_ON(sizeof(*(ptr)) != 8);				\

	cmpxchg((ptr), (o), (n));					\

})

#else /* CONFIG_64BIT */

arch/s390/include/asm/percpu.h

+68 −0
Original line number Diff line number Diff line 
#ifndef __ARCH_S390_PERCPU__

#define __ARCH_S390_PERCPU__



#include <linux/preempt.h>

#include <asm/cmpxchg.h>



/*

 * s390 uses its own implementation for per cpu data, the offset of

 * the cpu local data area is cached in the cpu's lowcore memory.
@@ -16,6 +19,71 @@ 
#define ARCH_NEEDS_WEAK_PER_CPU

#endif



#define arch_irqsafe_cpu_to_op(pcp, val, op)				\

do {									\

	typedef typeof(pcp) pcp_op_T__;					\

	pcp_op_T__ old__, new__, prev__;				\

	pcp_op_T__ *ptr__;						\

	preempt_disable();						\

	ptr__ = __this_cpu_ptr(&(pcp));					\

	prev__ = *ptr__;						\

	do {								\

		old__ = prev__;						\

		new__ = old__ op (val);					\

		switch (sizeof(*ptr__)) {				\

		case 8:							\

			prev__ = cmpxchg64(ptr__, old__, new__);	\

			break;						\

		default:						\

			prev__ = cmpxchg(ptr__, old__, new__);		\

		}							\

	} while (prev__ != old__);					\

	preempt_enable();						\

} while (0)



#define irqsafe_cpu_add_1(pcp, val) arch_irqsafe_cpu_to_op(pcp, val, +)

#define irqsafe_cpu_add_2(pcp, val) arch_irqsafe_cpu_to_op(pcp, val, +)

#define irqsafe_cpu_add_4(pcp, val) arch_irqsafe_cpu_to_op(pcp, val, +)

#define irqsafe_cpu_add_8(pcp, val) arch_irqsafe_cpu_to_op(pcp, val, +)



#define irqsafe_cpu_and_1(pcp, val) arch_irqsafe_cpu_to_op(pcp, val, &)

#define irqsafe_cpu_and_2(pcp, val) arch_irqsafe_cpu_to_op(pcp, val, &)

#define irqsafe_cpu_and_4(pcp, val) arch_irqsafe_cpu_to_op(pcp, val, &)

#define irqsafe_cpu_and_8(pcp, val) arch_irqsafe_cpu_to_op(pcp, val, &)



#define irqsafe_cpu_or_1(pcp, val) arch_irqsafe_cpu_to_op(pcp, val, |)

#define irqsafe_cpu_or_2(pcp, val) arch_irqsafe_cpu_to_op(pcp, val, |)

#define irqsafe_cpu_or_4(pcp, val) arch_irqsafe_cpu_to_op(pcp, val, |)

#define irqsafe_cpu_or_8(pcp, val) arch_irqsafe_cpu_to_op(pcp, val, |)



#define irqsafe_cpu_xor_1(pcp, val) arch_irqsafe_cpu_to_op(pcp, val, ^)

#define irqsafe_cpu_xor_2(pcp, val) arch_irqsafe_cpu_to_op(pcp, val, ^)

#define irqsafe_cpu_xor_4(pcp, val) arch_irqsafe_cpu_to_op(pcp, val, ^)

#define irqsafe_cpu_xor_8(pcp, val) arch_irqsafe_cpu_to_op(pcp, val, ^)



#define arch_irqsafe_cpu_cmpxchg(pcp, oval, nval)			\

({									\

	typedef typeof(pcp) pcp_op_T__;					\

	pcp_op_T__ ret__;						\

	pcp_op_T__ *ptr__;						\

	preempt_disable();						\

	ptr__ = __this_cpu_ptr(&(pcp));					\

	switch (sizeof(*ptr__)) {					\

	case 8:								\

		ret__ = cmpxchg64(ptr__, oval, nval);			\

		break;							\

	default:							\

		ret__ = cmpxchg(ptr__, oval, nval);			\

	}								\

	preempt_enable();						\

	ret__;								\

})



#define irqsafe_cpu_cmpxchg_1(pcp, oval, nval) arch_irqsafe_cpu_cmpxchg(pcp, oval, nval)

#define irqsafe_cpu_cmpxchg_2(pcp, oval, nval) arch_irqsafe_cpu_cmpxchg(pcp, oval, nval)

#define irqsafe_cpu_cmpxchg_4(pcp, oval, nval) arch_irqsafe_cpu_cmpxchg(pcp, oval, nval)

#define irqsafe_cpu_cmpxchg_8(pcp, oval, nval) arch_irqsafe_cpu_cmpxchg(pcp, oval, nval)



#include <asm-generic/percpu.h>



#endif /* __ARCH_S390_PERCPU__ */