On Tue, Jan 08, 2013 at 03:40:11PM -0800, Yinghai Lu wrote: > On Mon, Jan 7, 2013 at 7:50 PM, Yinghai Lu <ying...@kernel.org> wrote: > > On Mon, Jan 7, 2013 at 7:13 PM, Eric W. Biederman <ebied...@xmission.com> > > wrote: > >> I meant we should detect failure to allocate bounce buffers in in > >> swiotlb_init() instead of panicing. > >> > >> I meant swiotlb_map_single() should either panic or simply fail. > >> > >> If I have read lib/swiotlb.c correctly the only place we allocate a > >> bounce buffer is in swiotlb_map_single. If there are more places we can > >> allocate bounce buffers those need to be handled as well. > > > > ok, will give it a try. > > please check if you are ok with attached. > > looks like it need more change of lines.
The swiotlb_full check I don't believe is neccessary. You won't ever get to that unless swiotlb_map_page has at least provided a bounce buffer. And if the swiotlb_map_page does not have a bounce buffer it will exit with: + if (no_iotlb_memory) + return SWIOTLB_MAP_ERROR; + which is dangerous. That is b/c there are drivers that don't use the dma_mapping_error check (so check the bus address after calling pci_map_*). This means they would try to do DMA on 0xffffffff (yikes!). That is reason the failback (v_overflow_buffer) is still in usage - b/c we have drivers that might just do this and this is the last resort for them. And until those drivers are fixed - we _need_ this fallback to work. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
