From 15a23ffa2fc91cebdac44d4aee994f59d5c28dc0 Mon Sep 17 00:00:00 2001 From: Hugh Dickins Date: Sat, 29 Oct 2005 18:16:01 -0700 Subject: [PATCH] mm: tlb_gather_mmu get_cpu_var tlb_gather_mmu dates from before kernel preemption was allowed, and uses smp_processor_id or __get_cpu_var to find its per-cpu mmu_gather. That works because it's currently only called after getting page_table_lock, which is not dropped until after the matching tlb_finish_mmu. But don't rely on that, it will soon change: now disable preemption internally by proper get_cpu_var in tlb_gather_mmu, put_cpu_var in tlb_finish_mmu. Signed-off-by: Hugh Dickins Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/asm-generic/tlb.h | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) (limited to 'include/asm-generic/tlb.h') diff --git a/include/asm-generic/tlb.h b/include/asm-generic/tlb.h index 7d0298347ee..c8232622c8d 100644 --- a/include/asm-generic/tlb.h +++ b/include/asm-generic/tlb.h @@ -35,9 +35,7 @@ #endif /* struct mmu_gather is an opaque type used by the mm code for passing around - * any data needed by arch specific code for tlb_remove_page. This structure - * can be per-CPU or per-MM as the page table lock is held for the duration of - * TLB shootdown. + * any data needed by arch specific code for tlb_remove_page. */ struct mmu_gather { struct mm_struct *mm; @@ -57,7 +55,7 @@ DECLARE_PER_CPU(struct mmu_gather, mmu_gathers); static inline struct mmu_gather * tlb_gather_mmu(struct mm_struct *mm, unsigned int full_mm_flush) { - struct mmu_gather *tlb = &per_cpu(mmu_gathers, smp_processor_id()); + struct mmu_gather *tlb = &get_cpu_var(mmu_gathers); tlb->mm = mm; @@ -85,7 +83,7 @@ tlb_flush_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end) /* tlb_finish_mmu * Called at the end of the shootdown operation to free up any resources - * that were required. The page table lock is still held at this point. + * that were required. */ static inline void tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end) @@ -101,6 +99,8 @@ tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end) /* keep the page table cache within bounds */ check_pgt_cache(); + + put_cpu_var(mmu_gathers); } static inline unsigned int -- cgit v1.2.3