Messages in this thread | | | From | Arnd Bergmann <> | Subject | Re: [PATCH 09/16] dma-debug: add checking for map/unmap_page/single | Date | Wed, 21 Jan 2009 01:17:32 +0100 |
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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)));
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
Arnd <><
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