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| author | Christoph Lameter <cl@linux.com> | 2010-12-08 16:22:55 +0100 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2010-12-17 15:07:19 +0100 |
| commit | 909ea96468096b07fbb41aaf69be060d92bd9271 (patch) | |
| tree | a7e015edd96b5f674874fe78cdd889769e130a2a /include | |
| parent | 780f36d8b3fa9572f731d4fb85067b2e45e6f993 (diff) | |
| download | linux-stable-909ea96468096b07fbb41aaf69be060d92bd9271.tar.gz linux-stable-909ea96468096b07fbb41aaf69be060d92bd9271.tar.bz2 linux-stable-909ea96468096b07fbb41aaf69be060d92bd9271.zip | |
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 <penberg@cs.helsinki.fi>
Cc: Hugh Dickins <hughd@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Acked-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/asm-generic/irq_regs.h | 8 | ||||
| -rw-r--r-- | include/linux/elevator.h | 12 | ||||
| -rw-r--r-- | include/linux/kernel_stat.h | 2 |
3 files changed, 8 insertions, 14 deletions
diff --git a/include/asm-generic/irq_regs.h b/include/asm-generic/irq_regs.h index 5ae1d07d4a12..6bf9355fa7eb 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 4fd978e7eb83..4d857973d2c9 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 ad54c846911b..44e83ba12b5b 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; |