2014-11-29 01:32:51

by Zeng Tao

Subject: [PATCH] staging: ion : ion_cma_heap: fix bug for highmem cma

when cma is located in highmem, virt_to_page will not
work the right way, use pfn_to_page instead.

Signed-off-by: Zeng Tao <[email protected]>
---
drivers/staging/android/ion/ion_cma_heap.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/staging/android/ion/ion_cma_heap.c b/drivers/staging/android/ion/ion_cma_heap.c
index f8cabcb..cc45fc0 100644
--- a/drivers/staging/android/ion/ion_cma_heap.c
+++ b/drivers/staging/android/ion/ion_cma_heap.c
@@ -47,7 +47,7 @@ struct ion_cma_buffer_info {
static int ion_cma_get_sgtable(struct device *dev, struct sg_table *sgt,
void *cpu_addr, dma_addr_t handle, size_t size)
{
- struct page *page = virt_to_page(cpu_addr);
+ struct page *page = pfn_to_page(handle >> PAGE_SHIFT);
int ret;

ret = sg_alloc_table(sgt, 1, GFP_KERNEL);
--
1.9.1

2014-12-01 18:36:18

by Laura Abbott

Subject: Re: [PATCH] staging: ion : ion_cma_heap: fix bug for highmem cma

On 11/28/2014 5:31 PM, Zeng Tao wrote:
> when cma is located in highmem, virt_to_page will not
> work the right way, use pfn_to_page instead.
>
> Signed-off-by: Zeng Tao <[email protected]>
> ---
> drivers/staging/android/ion/ion_cma_heap.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/staging/android/ion/ion_cma_heap.c b/drivers/staging/android/ion/ion_cma_heap.c
> index f8cabcb..cc45fc0 100644
> --- a/drivers/staging/android/ion/ion_cma_heap.c
> +++ b/drivers/staging/android/ion/ion_cma_heap.c
> @@ -47,7 +47,7 @@ struct ion_cma_buffer_info {
> static int ion_cma_get_sgtable(struct device *dev, struct sg_table *sgt,
> void *cpu_addr, dma_addr_t handle, size_t size)
> {
> - struct page *page = virt_to_page(cpu_addr);
> + struct page *page = pfn_to_page(handle >> PAGE_SHIFT);

There's a comment right above this that notes this function could be replaced
with dma_common_get_sgtable when it's available. That function is now
present in drivers/base/dma-mapping.c although it has the same bug. I'd
suggest fixing the bug in dma_common_get_sgtable and switching Ion to use
that function instead.

> int ret;
>
> ret = sg_alloc_table(sgt, 1, GFP_KERNEL);
>

Thanks,
Laura

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