From 28634a07d3f72f2c186ad465e58f72e728c5cd4e Mon Sep 17 00:00:00 2001 From: Heiko Carstens Date: Mon, 17 Sep 2012 06:38:22 +0200 Subject: [PATCH] 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 Signed-off-by: Martin Schwidefsky --- arch/s390/include/asm/percpu.h | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/arch/s390/include/asm/percpu.h b/arch/s390/include/asm/percpu.h index 6537e72e0853..7adebfc0c6dc 100644 --- a/arch/s390/include/asm/percpu.h +++ b/arch/s390/include/asm/percpu.h @@ -84,6 +84,24 @@ do { \ #define this_cpu_cmpxchg_4(pcp, oval, nval) arch_this_cpu_cmpxchg(pcp, oval, nval) #define this_cpu_cmpxchg_8(pcp, oval, nval) arch_this_cpu_cmpxchg(pcp, oval, nval) +#define arch_this_cpu_xchg(pcp, nval) \ +({ \ + typeof(pcp) *ptr__; \ + typeof(pcp) ret__; \ + preempt_disable(); \ + ptr__ = __this_cpu_ptr(&(pcp)); \ + ret__ = xchg(ptr__, nval); \ + preempt_enable(); \ + ret__; \ +}) + +#define this_cpu_xchg_1(pcp, nval) arch_this_cpu_xchg(pcp, nval) +#define this_cpu_xchg_2(pcp, nval) arch_this_cpu_xchg(pcp, nval) +#define this_cpu_xchg_4(pcp, nval) arch_this_cpu_xchg(pcp, nval) +#ifdef CONFIG_64BIT +#define this_cpu_xchg_8(pcp, nval) arch_this_cpu_xchg(pcp, nval) +#endif + #include #endif /* __ARCH_S390_PERCPU__ */ -- 2.20.1