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SubjectRe: [PATCH] ARM: mm: clean-up in order to reduce to call kmap_high_get()
On Mon, 4 Mar 2013, Joonsoo Kim wrote:

> In kmap_atomic(), kmap_high_get() is invoked for checking already
> mapped area. In __flush_dcache_page() and dma_cache_maint_page(),
> we explicitly call kmap_high_get() before kmap_atomic()
> when cache_is_vipt(), so kmap_high_get() can be invoked twice.
> This is useless operation, so remove one.
>
> Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>

Acked-by: Nicolas Pitre <nico@linaro.org>

> diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
> index c7e3759..b7711be 100644
> --- a/arch/arm/mm/dma-mapping.c
> +++ b/arch/arm/mm/dma-mapping.c
> @@ -822,16 +822,16 @@ static void dma_cache_maint_page(struct page *page, unsigned long offset,
> if (PageHighMem(page)) {
> if (len + offset > PAGE_SIZE)
> len = PAGE_SIZE - offset;
> - vaddr = kmap_high_get(page);
> - if (vaddr) {
> - vaddr += offset;
> - op(vaddr, len, dir);
> - kunmap_high(page);
> - } else if (cache_is_vipt()) {
> - /* unmapped pages might still be cached */
> + if (cache_is_vipt()) {
> vaddr = kmap_atomic(page);
> op(vaddr + offset, len, dir);
> kunmap_atomic(vaddr);
> + } else {
> + vaddr = kmap_high_get(page);
> + if (vaddr) {
> + op(vaddr + offset, len, dir);
> + kunmap_high(page);
> + }
> }
> } else {
> vaddr = page_address(page) + offset;
> diff --git a/arch/arm/mm/flush.c b/arch/arm/mm/flush.c
> index 1c8f7f5..e6a03d0 100644
> --- a/arch/arm/mm/flush.c
> +++ b/arch/arm/mm/flush.c
> @@ -170,15 +170,18 @@ void __flush_dcache_page(struct address_space *mapping, struct page *page)
> if (!PageHighMem(page)) {
> __cpuc_flush_dcache_area(page_address(page), PAGE_SIZE);
> } else {
> - void *addr = kmap_high_get(page);
> - if (addr) {
> - __cpuc_flush_dcache_area(addr, PAGE_SIZE);
> - kunmap_high(page);
> - } else if (cache_is_vipt()) {
> - /* unmapped pages might still be cached */
> + void *addr;
> +
> + if (cache_is_vipt()) {
> addr = kmap_atomic(page);
> __cpuc_flush_dcache_area(addr, PAGE_SIZE);
> kunmap_atomic(addr);
> + } else {
> + addr = kmap_high_get(page);
> + if (addr) {
> + __cpuc_flush_dcache_area(addr, PAGE_SIZE);
> + kunmap_high(page);
> + }
> }
> }
>
> --
> 1.7.9.5
>


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