This fixes a nasty memory corruption bug when using userptr I/O.
The function videobuf_pages_to_sg() sets up the scatter-gather list for the
DMA transfer to the userspace pages. The first transfer is setup correctly
(the size is set to PAGE_SIZE - offset), but all other transfers have size
PAGE_SIZE. This is wrong for the last transfer which may be less than PAGE_SIZE.
Most, if not all, drivers will program the boards DMA engine correctly, i.e.
even though the size in the last sg element is wrong, they will do their
own size calculations and make sure the right amount is DMA-ed, and so seemingly
prevent memory corruption.
However, behind the scenes the dynamic DMA mapping support (in lib/swiotlb.c)
may create bounce buffers if the memory pages are not in DMA-able memory.
This happens for example on a 64-bit linux with a board that only supports
32-bit DMA.
These bounce buffers DO use the information in the sg list to determine the
size. So while the DMA engine transfers the correct amount of data, when the
data is 'bounced' back too much is copied, causing buffer overwrites.
The fix is simple: calculate and set the correct size for the last sg list
element.
Signed-off-by: Hans Verkuil <hans.verkuil@tandberg.com>
Cc: stable@kernel.org
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
The videobuf_dmabuf and videobuf_vmalloc_memory fields have a vmalloc
field to store the kernel virtual address of vmalloc'ed buffers. Rename
the field to vaddr.
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Those functions are only called inside videobuf-dma-sg.c, make them
static.
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Instead of creating dirty wrappers around videobuf_dma_map/unmap that
create a dummy videobuf_queue structure, modify videobuf_dma_map/unmap
to take a device pointer argument and use it directly. The
videobuf_sg_dma_map/unmap then become unused and can be removed.
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
While analyzing one of the videobuf patches, I noticed that
videobuf_dma_sync is only used internally inside videobuf-dma-sg.
So, let's remove this function, merging the code at __videobuf_dma_sync()
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
The videobuf_queue_ops function vector is not declared constant, but
there's no need for the videobuf layer to ever change it. Make it const
so that videobuf users can make their operations const without warnings.
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Move DMA-mapping.txt to Documentation/PCI/.
DMA-mapping.txt was supposed to be moved from Documentation/ to
Documentation/PCI/. The 00-INDEX files in those two directories
were updated, along with a few other text files, but the file
itself somehow escaped being moved, so move it and update more
text files and source files with its new location.
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
videobuf-dma-sg does not need to depend on PCI. Switch it to using generic
DMA API, convert all affected drivers, relax Kconfig restriction, improve
compile-time type checking, fix some Coding Style violations while at it.
Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@pengutronix.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
Before the videobuf redesign, a procedure for re-using videobuf without PCI
scatter/gather where provided by changing the pci-dependent operations by
other operations.
With the newer approach, those methods are obsolete and can safelly be removed.
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
video-buf currently does two different tasks:
- Manages video buffers with a common code that allows
implementing all the V4L2 different modes of buffering;
- Controls memory allocations
While the first task is generic, the second were written to support PCI DMA
Scatter/Gather needs. The original approach can't even work for those
video capture hardware that don't support scatter/gather.
I did one approach to make it more generic. While the approach worked
fine for vivi driver, it were not generic enough to handle USB needs.
This patch creates two different modules, one containing the generic
video buffer handling (videobuf-core) and another with PCI DMA S/G.
After this patch, it would be simpler to write an USB video-buf and a
non-SG DMA module.
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
http://thread.gmane.org/gmane.comp.video.video4linux/34978/focus=34981
Reviewed-by: Ricardo Cerqueira <v4l@cerqueira.org>
