Hello,
On 2013-11-06 20:48, Ricardo Ribalda Delgado wrote:
Memory exported via remap_pfn_range cannot be remapped via
get_user_pages.
Other videobuf2 methods (like the dma-contig) supports io memory.
This patch adds support for this kind of memory.
Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@xxxxxxxxx>
---
drivers/media/v4l2-core/videobuf2-dma-sg.c | 35 ++++++++++++++++++++++++++----
1 file changed, 31 insertions(+), 4 deletions(-)
diff --git a/drivers/media/v4l2-core/videobuf2-dma-sg.c b/drivers/media/v4l2-core/videobuf2-dma-sg.c
index 2f86054..44ddfe1 100644
--- a/drivers/media/v4l2-core/videobuf2-dma-sg.c
+++ b/drivers/media/v4l2-core/videobuf2-dma-sg.c
@@ -40,6 +40,7 @@ struct vb2_dma_sg_buf {
unsigned int num_pages;
atomic_t refcount;
struct vb2_vmarea_handler handler;
+ struct vm_area_struct *vma;
};
static void vb2_dma_sg_put(void *buf_priv);
@@ -155,6 +156,11 @@ static void vb2_dma_sg_put(void *buf_priv)
}
}
+static inline int vma_is_io(struct vm_area_struct *vma)
+{
+ return !!(vma->vm_flags & (VM_IO | VM_PFNMAP));
+}
+
static void *vb2_dma_sg_get_userptr(void *alloc_ctx, unsigned long vaddr,
unsigned long size, int write)
{
@@ -180,7 +186,26 @@ static void *vb2_dma_sg_get_userptr(void *alloc_ctx, unsigned long vaddr,
if (!buf->pages)
return NULL;
- num_pages_from_user = get_user_pages(current, current->mm,
+ buf->vma = find_vma(current->mm, vaddr);
+ if (!buf->vma) {
+ dprintk(1, "no vma for address %lu\n", vaddr);
+ return NULL;
+ }
+
+ if (vma_is_io(buf->vma)) {
+ for (num_pages_from_user = 0;
+ num_pages_from_user < buf->num_pages;
+ ++num_pages_from_user, vaddr += PAGE_SIZE) {
+ unsigned long pfn;
+
+ if (follow_pfn(buf->vma, vaddr, &pfn)) {
+ dprintk(1, "no page for address %lu\n", vaddr);
+ break;
+ }
Please add a call to vb2_get_vma(vma) to protect that io memory from
being freed, see videobuf2-dma-contig.c for the reference. It is not
100% perfect way, but right now it works for the typical memory regions
created by other multimedia devices. You will also need to call
vb2_put_vma() later on release.
+ buf->pages[num_pages_from_user] = pfn_to_page(pfn);
+ }
+ } else
+ num_pages_from_user = get_user_pages(current, current->mm,
vaddr & PAGE_MASK,
buf->num_pages,
write,
@@ -201,8 +226,9 @@ userptr_fail_alloc_table_from_pages:
userptr_fail_get_user_pages:
dprintk(1, "get_user_pages requested/got: %d/%d]\n",
num_pages_from_user, buf->num_pages);
- while (--num_pages_from_user >= 0)
- put_page(buf->pages[num_pages_from_user]);
+ if (!vma_is_io(buf->vma))
+ while (--num_pages_from_user >= 0)
+ put_page(buf->pages[num_pages_from_user]);
kfree(buf->pages);
kfree(buf);
return NULL;
@@ -225,7 +251,8 @@ static void vb2_dma_sg_put_userptr(void *buf_priv)
while (--i >= 0) {
if (buf->write)
set_page_dirty_lock(buf->pages[i]);
- put_page(buf->pages[i]);
+ if (!vma_is_io(buf->vma))
+ put_page(buf->pages[i]);
}
kfree(buf->pages);
kfree(buf);
Best regards
--
Marek Szyprowski, PhD
Samsung R&D Institute Poland
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