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| author | Christoph Lameter <cl@linux.com> | 2010-12-06 11:40:03 -0600 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2010-12-17 15:18:04 +0100 |
| commit | cfb824349556904b319464139be5c75fce983b0d (patch) | |
| tree | e0f0094ffc8732457ae1233e5e2890788e3817ff | |
| parent | 908ee0f122bf2a67414854af5b90c6621d186a71 (diff) | |
| download | linux-cfb824349556904b319464139be5c75fce983b0d.tar.gz linux-cfb824349556904b319464139be5c75fce983b0d.tar.bz2 linux-cfb824349556904b319464139be5c75fce983b0d.zip | |
highmem: Use this_cpu_xx_return() operations
Use this_cpu operations to optimize access primitives for highmem.
The main effect is the avoidance of address calculations through the
use of a segment prefix.
V3->V4
- kmap_atomic_idx: Do not return a value.
- Use __this_cpu_dec without HIGHMEM_DEBUG
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
| -rw-r--r-- | include/linux/highmem.h | 13 |
1 files changed, 8 insertions, 5 deletions
diff --git a/include/linux/highmem.h b/include/linux/highmem.h index b676c585574e..3a93f73a8acc 100644 --- a/include/linux/highmem.h +++ b/include/linux/highmem.h @@ -81,7 +81,8 @@ DECLARE_PER_CPU(int, __kmap_atomic_idx); static inline int kmap_atomic_idx_push(void) { - int idx = __get_cpu_var(__kmap_atomic_idx)++; + int idx = __this_cpu_inc_return(__kmap_atomic_idx) - 1; + #ifdef CONFIG_DEBUG_HIGHMEM WARN_ON_ONCE(in_irq() && !irqs_disabled()); BUG_ON(idx > KM_TYPE_NR); @@ -91,16 +92,18 @@ static inline int kmap_atomic_idx_push(void) static inline int kmap_atomic_idx(void) { - return __get_cpu_var(__kmap_atomic_idx) - 1; + return __this_cpu_read(__kmap_atomic_idx) - 1; } -static inline int kmap_atomic_idx_pop(void) +static inline void kmap_atomic_idx_pop(void) { - int idx = --__get_cpu_var(__kmap_atomic_idx); #ifdef CONFIG_DEBUG_HIGHMEM + int idx = __this_cpu_dec_return(__kmap_atomic_idx); + BUG_ON(idx < 0); +#else + __this_cpu_dec(__kmap_atomic_idx); #endif - return idx; } #endif |