[PATCH v2]videobuf_dma_sg: a new implementation for mmap

[Figo.zhang]

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().

in v2, if mem->dma.vmalloc is NULL at video_vm_ops->fault(), it will
alloc memory by vmalloc_32().

Signed-off-by: Figo.zhang <figo1...@gmail.com>
---
 drivers/media/video/videobuf-dma-sg.c |   51
+++++++++++++++++++++++++++------
 1 files changed, 42 insertions(+), 9 deletions(-)

diff --git a/drivers/media/video/videobuf-dma-sg.c
b/drivers/media/video/videobuf-dma-sg.c
index 8359e6b..767483d 100644
--- a/drivers/media/video/videobuf-dma-sg.c
+++ b/drivers/media/video/videobuf-dma-sg.c
@@ -201,10 +201,11 @@ int videobuf_dma_init_kernel(struct
videobuf_dmabuf *dma, int direction,
        dprintk(1, "init kernel [%d pages]\n", nr_pages);
 
        dma->direction = direction;
-       dma->vmalloc = vmalloc_32(nr_pages << PAGE_SHIFT);
-       if (NULL == dma->vmalloc) {
-               dprintk(1, "vmalloc_32(%d pages) failed\n", nr_pages);
-               return -ENOMEM;
+       if (!dma->vmalloc)
+               dma->vmalloc = vmalloc_32(nr_pages << PAGE_SHIFT);
+               if (NULL == dma->vmalloc) {
+                       dprintk(1, "vmalloc_32(%d pages) failed\n", nr_pages);
+                       return -ENOMEM;
        }
 
        dprintk(1, "vmalloc is at addr 0x%08lx, size=%d\n",
@@ -397,16 +398,48 @@ 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) {
+               mem->dma.vmalloc = vmalloc_32(PAGE_ALIGN(q->bufs[first]->size));
+               if (NULL == mem->dma.vmalloc) {
+                       dprintk(1, "%s: vmalloc_32() failed\n", __func__);
+                       return VM_FAULT_OOM;
+               }
+       } else
+               page = vmalloc_to_page(mem->dma.vmalloc+
+                               (offset & (~PAGE_MASK)));
+       mutex_unlock(&q->vb_lock);
+
        vmf->page = page;
 
        return 0;



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