Hi,
On Tuesday 27 July 2010 14:21:40 Figo.zhang wrote:
> a mmap issue for videobuf-dma-sg: it will alloc a new page for mmaping
> when it encounter page fault at video_vm_ops->fault().
>
> a new implementation for mmap, it translate the vmalloc to page at
> video_vm_ops->fault().
How is that supposed to work ? mem->dma.vmalloc is NULL in the vm_fault
handler for V4L2_MEMORY_MMAP buffers. Have you tested the code at all ?
> Signed-off-by: Figo.zhang <figo1802@xxxxxxxxx>
> ---
> drivers/media/video/videobuf-dma-sg.c | 38
> ++++++++++++++++++++++++++++----
> 1 files changed, 33 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/media/video/videobuf-dma-sg.c
> b/drivers/media/video/videobuf-dma-sg.c
> index 8359e6b..c9a8817 100644
> --- a/drivers/media/video/videobuf-dma-sg.c
> +++ b/drivers/media/video/videobuf-dma-sg.c
> @@ -397,16 +397,44 @@ static void videobuf_vm_close(struct
> vm_area_struct *vma)
> */
> static int videobuf_vm_fault(struct vm_area_struct *vma, struct
> vm_fault *vmf)
> {
> - struct page *page;
> + struct page *page = NULL;
> + struct videobuf_mapping *map = vma->vm_private_data;
> + struct videobuf_queue *q = map->q;
> + struct videobuf_dma_sg_memory *mem = NULL;
> +
> + unsigned long offset;
> + unsigned long page_nr;
> + int first;
>
> dprintk(3, "fault: fault @ %08lx [vma %08lx-%08lx]\n",
> (unsigned long)vmf->virtual_address,
> vma->vm_start, vma->vm_end);
>
> - page = alloc_page(GFP_USER | __GFP_DMA32);
> - if (!page)
> - return VM_FAULT_OOM;
> - clear_user_highpage(page, (unsigned long)vmf->virtual_address);
> + mutex_lock(&q->vb_lock);
> +
> + offset = (unsigned long)vmf->virtual_address - vma->vm_start;
> + page_nr = offset >> PAGE_SHIFT;
> +
> + for (first = 0; first < VIDEO_MAX_FRAME; first++) {
> + if (NULL == q->bufs[first])
> + continue;
> +
> + MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
> +
> + if (q->bufs[first]->map == map)
> + break;
> + }
> +
> + mem = q->bufs[first]->priv;
> + if (!mem)
> + return VM_FAULT_SIGBUS;
> + if (mem->dma.vmalloc)
> + page = vmalloc_to_page(mem->dma.vmalloc+
> + (offset & (~PAGE_MASK)));
> + if (mem->dma.pages)
> + page = mem->dma.pages[page_nr];
> + mutex_unlock(&q->vb_lock);
> +
> vmf->page = page;
>
> return 0;
--
Regards,
Laurent Pinchart
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