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| author | Heiko Carstens <heiko.carstens@de.ibm.com> | 2012-09-17 08:38:22 +0400 |
|---|---|---|
| committer | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2012-09-26 17:45:24 +0400 |
| commit | 28634a07d3f72f2c186ad465e58f72e728c5cd4e (patch) | |
| tree | bc3b2063834b72205470efea903d366f42ba255b /arch/s390 | |
| parent | 0ed23b3e495807809873bb607d12c857ae9ab7c2 (diff) | |
| download | linux-28634a07d3f72f2c186ad465e58f72e728c5cd4e.tar.xz | |
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>
Diffstat (limited to 'arch/s390')
| -rw-r--r-- | arch/s390/include/asm/percpu.h | 18 |
1 files changed, 18 insertions, 0 deletions
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 <asm-generic/percpu.h> #endif /* __ARCH_S390_PERCPU__ */ |