Tomasz, On Thu, Aug 8, 2013 at 6:54 AM, Tomasz Figa <[email protected]> wrote: ... >> + BUG_ON(lv1ent_section(sent)); > > Is this condition really a critical one, to the point that the system > should not continue execution? > ... >> if (lv1ent_page(sent)) { >> - if (*pgcnt != NUM_LV2ENTRIES) >> - return -EADDRINUSE; >> - >> + BUG_ON(*pgcnt != NUM_LV2ENTRIES); > > Ditto.
I can't speak to the previous BUG_ON(). I believe the EADDRESSINUSE failures could be either WARN_ON or BUG_ON. This condition is clearly a bug in the generic IOMMU allocator and I think that's why KyongHo Cho used BUG_ON. Handing out duplicate addresses will generally lead to some sort of data corruption or other fault depending on how robust the underlying device drivers are written. So my preference is a BUG_ON to immediately flag this condition instead of hoping a device driver will correctly handling the dma mapping failure (Some do, most currently don't). WARN_ON() + return -EADDRESSINUSE would be a good alternative. thanks, grant -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
