On Fri, Mar 12, 2021 at 06:11:17PM +0000, Robin Murphy wrote: > Sure, that's how things stand immediately after this patch. But then > someone comes along with the perfectly reasonable argument for returning > more expressive error information for regular mapping failures as well > (because sometimes those can be terminal too, as above), we start to get > divergent behaviour across architectures and random bits of old code subtly > breaking down the line. *That* is what makes me wary of making a > fundamental change to a long-standing "nonzero means success" interface... Agreed. IMHO dma_map_sg actually needs to be switched to return unsigned to help root this out, going the other way is no helpful.