Messages in this thread | | | Date | Wed, 20 Jan 2010 11:56:34 +0100 | From | Joerg Roedel <> | Subject | Re: [PATCH] asm-generic: dma: Add BUG_ON for uninitialized dma_ops |
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On Wed, Jan 20, 2010 at 11:08:31AM +0100, monstr@monstr.eu wrote: > From: Michal Simek <monstr@monstr.eu> > > 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@monstr.eu> > --- > 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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