From cfb824349556904b319464139be5c75fce983b0d Mon Sep 17 00:00:00 2001 From: Christoph Lameter Date: Mon, 6 Dec 2010 11:40:03 -0600 Subject: [PATCH] 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 Cc: Catalin Marinas Acked-by: H. Peter Anvin Signed-off-by: Christoph Lameter Signed-off-by: Tejun Heo --- include/linux/highmem.h | 13 ++++++++----- 1 file 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 -- 2.34.1