From 909ea96468096b07fbb41aaf69be060d92bd9271 Mon Sep 17 00:00:00 2001 From: Christoph Lameter Date: Wed, 8 Dec 2010 16:22:55 +0100 Subject: core: Replace __get_cpu_var with __this_cpu_read if not used for an address. __get_cpu_var() can be replaced with this_cpu_read and will then use a single read instruction with implied address calculation to access the correct per cpu instance. However, the address of a per cpu variable passed to __this_cpu_read() cannot be determined (since it's an implied address conversion through segment prefixes). Therefore apply this only to uses of __get_cpu_var where the address of the variable is not used. Cc: Pekka Enberg Cc: Hugh Dickins Cc: Thomas Gleixner Acked-by: H. Peter Anvin Signed-off-by: Christoph Lameter Signed-off-by: Tejun Heo --- include/asm-generic/irq_regs.h | 8 ++++---- include/linux/elevator.h | 12 +++--------- include/linux/kernel_stat.h | 2 +- 3 files changed, 8 insertions(+), 14 deletions(-) (limited to 'include') diff --git a/include/asm-generic/irq_regs.h b/include/asm-generic/irq_regs.h index 5ae1d07..6bf9355 100644 --- a/include/asm-generic/irq_regs.h +++ b/include/asm-generic/irq_regs.h @@ -22,15 +22,15 @@ DECLARE_PER_CPU(struct pt_regs *, __irq_regs); static inline struct pt_regs *get_irq_regs(void) { - return __get_cpu_var(__irq_regs); + return __this_cpu_read(__irq_regs); } static inline struct pt_regs *set_irq_regs(struct pt_regs *new_regs) { - struct pt_regs *old_regs, **pp_regs = &__get_cpu_var(__irq_regs); + struct pt_regs *old_regs; - old_regs = *pp_regs; - *pp_regs = new_regs; + old_regs = __this_cpu_read(__irq_regs); + __this_cpu_write(__irq_regs, new_regs); return old_regs; } diff --git a/include/linux/elevator.h b/include/linux/elevator.h index 4fd978e..4d85797 100644 --- a/include/linux/elevator.h +++ b/include/linux/elevator.h @@ -195,15 +195,9 @@ enum { /* * io context count accounting */ -#define elv_ioc_count_mod(name, __val) \ - do { \ - preempt_disable(); \ - __get_cpu_var(name) += (__val); \ - preempt_enable(); \ - } while (0) - -#define elv_ioc_count_inc(name) elv_ioc_count_mod(name, 1) -#define elv_ioc_count_dec(name) elv_ioc_count_mod(name, -1) +#define elv_ioc_count_mod(name, __val) this_cpu_add(name, __val) +#define elv_ioc_count_inc(name) this_cpu_inc(name) +#define elv_ioc_count_dec(name) this_cpu_dec(name) #define elv_ioc_count_read(name) \ ({ \ diff --git a/include/linux/kernel_stat.h b/include/linux/kernel_stat.h index ad54c84..44e83ba 100644 --- a/include/linux/kernel_stat.h +++ b/include/linux/kernel_stat.h @@ -47,7 +47,7 @@ extern unsigned long long nr_context_switches(void); #ifndef CONFIG_GENERIC_HARDIRQS #define kstat_irqs_this_cpu(irq) \ - (kstat_this_cpu.irqs[irq]) + (this_cpu_read(kstat.irqs[irq]) struct irq_desc; -- cgit v1.1