On Wed, Jan 20, 2010 at 11:08:31AM +0100, monstr@xxxxxxxxx wrote:
> From: Michal Simek <monstr@xxxxxxxxx>
>
> Check that dma_ops are initialized correctly. Without this
> checking you get kernel fault and you don't know where the problem is.
>
> Signed-off-by: Michal Simek <monstr@xxxxxxxxx>
> ---
> include/asm-generic/dma-mapping-common.h | 10 ++++++++++
> 1 files changed, 10 insertions(+), 0 deletions(-)
>
> diff --git a/include/asm-generic/dma-mapping-common.h b/include/asm-generic/dma-mapping-common.h
> index e694263..ca8bc25 100644
> --- a/include/asm-generic/dma-mapping-common.h
> +++ b/include/asm-generic/dma-mapping-common.h
> @@ -15,6 +15,7 @@ static inline dma_addr_t dma_map_single_attrs(struct device *dev, void *ptr,
> dma_addr_t addr;
>
> kmemcheck_mark_initialized(ptr, size);
> + BUG_ON(!ops);
> BUG_ON(!valid_dma_direction(dir));
> addr = ops->map_page(dev, virt_to_page(ptr),
> (unsigned long)ptr & ~PAGE_MASK, size,
[...]
> @@ -169,6 +178,7 @@ dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg,
> {
> struct dma_map_ops *ops = get_dma_ops(dev);
>
> + BUG_ON(!ops);
> BUG_ON(!valid_dma_direction(dir));
> if (ops->sync_sg_for_device)
> ops->sync_sg_for_device(dev, sg, nelems, dir);
The more logical place for all these checks would be in get_dma_ops. But
I also question the value of the check. Every dma_ops implementation
that has survived a boot test shouldn't have this bug. So I see no point
in adding extra cycles to every dma-api call.
Joerg
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