Hi,
I have a V4L2 capture driver accepting a malloc'ed buffer.
The driver is using vb2_vmalloc_memops
(../drivers/media/v4l2-core/videobuf2-vmalloc.c) for user-space to kvaddr
translation.
Randomly, corrupted data is received by user-app.
So, the question is regarding the handling of get_userptr, put_userptr by
v4l2-core:
const struct vb2_mem_ops vb2_vmalloc_memops = {
........
.get_userptr = vb2_vmalloc_get_userptr, (get_user_pages() and
vm_map_ram())
.put_userptr = vb2_vmalloc_put_userptr, (set_page_dirty_lock() and
put_page())
.....
};
The driver prepares for the transaction by virtue of v4l2-core calling
get_userptr (QBUF)
After data is filled, driver puts on a done list (DQBUF)
We never mark the pages as dirty (or put_userptr) after a transaction is
complete.
Here, in v4l2 core (videobuf2-core.c) , we conditionally put_userptr - when a
QBUF with a different userptr on same index, or releasing buffers.
Is it correct? Probably seems to be the reason for corrupted data.
Regards,
Divneil --
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