[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 <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 4 insertions, 3 deletions

diff --git a/include/asm-arm26/tlb.h b/include/asm-arm26/tlb.h
index 1316352..8486b00 100644
--- a/include/asm-arm26/tlb.h
+++ b/include/asm-arm26/tlb.h
@@ -17,13 +17,12 @@ struct mmu_gather {
         unsigned int            avoided_flushes;
 };
 
-extern struct mmu_gather mmu_gathers[NR_CPUS];
+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)
 {
-        int cpu = smp_processor_id();
-        struct mmu_gather *tlb = &mmu_gathers[cpu];
+        struct mmu_gather *tlb = &get_cpu_var(mmu_gathers);
 
         tlb->mm = mm;
         tlb->freed = 0;
@@ -52,6 +51,8 @@ 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);
 }