On Tue, 2012-10-09 at 14:06 -0700, Andrew Morton wrote: > On Mon, 08 Oct 2012 11:08:06 -0600 > Shuah Khan <shuah.khan@xxxxxx> wrote: > > > Add dma-debug interface debug_dma_mapping_error() to debug drivers that fail > > to check dma mapping errors on addresses returned by dma_map_single() and > > dma_map_page() interfaces. This interface clears a flag set by > > debug_dma_map_page() to indicate that dma_mapping_error() has been called by > > the driver. When driver does unmap, debug_dma_unmap() checks the flag and if > > this flag is still set, prints warning message that includes call trace that > > leads up to the unmap. This interface can be called from dma_mapping_error() > > routines to enable dma mapping error check debugging. > > > > Tested: Intel iommu and swiotlb (iommu=soft) on x86-64 with > > CONFIG_DMA_API_DEBUG enabled and disabled. > > > > Signed-off-by: Shuah Khan <shuah.khan@xxxxxx> > > --- > > Documentation/DMA-API.txt | 12 ++++++ > > arch/x86/include/asm/dma-mapping.h | 1 + > > include/linux/dma-debug.h | 7 ++++ > > lib/dma-debug.c | 71 ++++++++++++++++++++++++++++++++++-- > > Third time lucky ... we still haven't fixed Documentation/DMA-API-HOWTO.txt! > > Please, go through it and update it to show people how to correctly use > these APIs. Yes. Still on my list. I am working on the documentation changes. I am planning to add usage examples that include calls to dma_mapping_error() after dma_map_[page/single] calls and programming mistakes to watch out for such as missing unmaps from error legs etc. -- Shuah _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/devel
