Messages in this thread | | | Date | Fri, 23 Jan 2009 11:28:27 +0100 | From | Joerg Roedel <> | Subject | Re: [PATCH 09/16] dma-debug: add checking for map/unmap_page/single |
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On Wed, Jan 21, 2009 at 01:17:32AM +0100, Arnd Bergmann wrote: > On Monday 19 January 2009, Joerg Roedel wrote: > > Impact: add debug callbacks for dma_{un}map_[page|single] > > In the discussion about "[PATCH] usb/mcs7830: Don't use buffers from > stack for USB transfers", I have raised the question of whether we can > add a check for the DMA address being on the stack, I guess this would > be the right place for it. > > Maybe you can add another check like: > > WARN_ON(is_kernel_stack(page_to_virt(page)));
Good idea. This would be the right place for such a check.
> Unfortunately, I can't think of a way to define a generic is_kernel_stack > function. On most architectures (all that put thread_info at the top of the > stack), something like this should work: > > #ifndef is_kernel_stack > static inline int is_kernel_stack(void *p) > { > return (unsigned long)p & ~(THREAD_SIZE - 1) == current_thread_info(); > } > #endif
Hmm, this function is indeed required on all architectures. If you send a patchset which adds it I will add the check for stack addresses to this debugging code :)
Joerg
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