On Thu, Aug 21, 2014 at 04:43:29PM +0100, Steve Capper wrote:
> --- a/arch/arm/include/asm/tlb.h
> +++ b/arch/arm/include/asm/tlb.h
> @@ -35,12 +35,39 @@
>
> #define MMU_GATHER_BUNDLE 8
>
> +#ifdef CONFIG_HAVE_RCU_TABLE_FREE
> +static inline void __tlb_remove_table(void *_table)
> +{
> + free_page_and_swap_cache((struct page *)_table);
> +}
> +
> +struct mmu_table_batch {
> + struct rcu_head rcu;
> + unsigned int nr;
> + void *tables[0];
> +};
> +
> +#define MAX_TABLE_BATCH \
> + ((PAGE_SIZE - sizeof(struct mmu_table_batch)) / sizeof(void *))
> +
> +extern void tlb_table_flush(struct mmu_gather *tlb);
> +extern void tlb_remove_table(struct mmu_gather *tlb, void *table);
> +
> +#define tlb_remove_entry(tlb, entry) tlb_remove_table(tlb, entry)
> +#else
> +#define tlb_remove_entry(tlb, entry) tlb_remove_page(tlb, entry)
> +#endif /* CONFIG_HAVE_RCU_TABLE_FREE */
> +
> /*
> * TLB handling. This allows us to remove pages from the page
> * tables, and efficiently handle the TLB issues.
> */
> struct mmu_gather {
> struct mm_struct *mm;
> +#ifdef CONFIG_HAVE_RCU_TABLE_FREE
> + struct mmu_table_batch *batch;
> + unsigned int need_flush;
> +#endif
We add need_flush here just because it is set by tlb_remove_table() but
it won't actually be checked by anything since arch/arm uses its own
version of tlb_flush_mmu(). But I wouldn't go for #ifdefs in the core
code either.
We should (as a separate patchset) convert arch/arm to generic
mmu_gather. I know Russell had objections in the past but mmu_gather has
evolved since and it's not longer inefficient (I think the only case is
shift_arg_pages but that's pretty much lost in the noise).
For this patch:
Reviewed-by: Catalin Marinas <catalin.marinas@xxxxxxx>
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