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[media] v4l: vb2-dma-contig: add reference counting for a device from allocator context

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This patch adds taking reference to the device for MMAP buffers.
Such buffers, may be exported using DMABUF mechanism. If the driver that
created a queue is unloaded then the queue is released, the device might be
released too.  However, buffers cannot be released if they are referenced by
DMABUF descriptor(s). The device pointer kept in a buffer must be valid for the
whole buffer's lifetime. Therefore MMAP buffers should take a reference to the
device to avoid risk of dangling pointers.

Signed-off-by: Tomasz Stanislawski <t.stanislaws@samsung.com>
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Tested-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
This commit is contained in:
Tomasz Stanislawski 2012-08-07 13:19:49 -03:00 committed by Mauro Carvalho Chehab
parent 9ef2cbeb81
commit 67a5d0cebf
1 changed files with 3 additions and 1 deletions
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4
drivers/media/v4l2-core/videobuf2-dma-contig.c
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@ -148,6 +148,7 @@ static void vb2_dc_put(void *buf_priv)
kfree(buf->sgt_base);
}
dma_free_coherent(buf->dev, buf->size, buf->vaddr, buf->dma_addr);
put_device(buf->dev);
kfree(buf);
}
@ -168,7 +169,8 @@ static void *vb2_dc_alloc(void *alloc_ctx, unsigned long size)
return ERR_PTR(-ENOMEM);
}
buf->dev = dev;
/* Prevent the device from being released while the buffer is used */
buf->dev = get_device(dev);
buf->size = size;
buf->handler.refcount = &buf->refcount;