On Tue, Sep 04, 2012 at 04:57:56PM -0600, Shuah Khan wrote: > On Tue, 2012-09-04 at 17:05 -0400, Konrad Rzeszutek Wilk wrote: > > On Sun, Sep 02, 2012 at 08:14:17AM -0600, Shuah Khan wrote: > > > A recent dma mapping error analysis effort showed that a large precentage > > > of dma_map_single() and dma_map_page() returns are not checked for mapping > > > errors. Reference: https://lkml.org/lkml/2012/8/10/326 > > > > > > > So were you able to catch some naughty drivers with this? > > I did compile a complete list of drivers that don't check dma mapping > errors from my analysis. Are you interested in seeing the full analysis? Yes, plus the authors of the drivers are probably interested in it as well. ..snip.. > > I was initially thinking that this patch would contain a state for the driver > > of whether after map it has called dma_mapping_error. So this function would > > increment some internal state, and if dma_mapping_error on that specific dma_addr > > it would decrement it. If it never occured, then we would print on the unmap > > that the device never had called dma_mapping_error on said dma_addr? > > That is a good idea. Let me see if I understand what you are saying > correctly. Add a new field to dma_debug_entry structure and keep state > and clear it if dma_mapping_error() is called. This will require adding > a debug interface for dma_mapping_error() which is not hard to do. Is > this close to what you are thinking? Right. It is more complex than this patch but it should provide a nicer "trap" mechanism to alert driver writers that they are not checking DMA addresses properly. -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
