On Sat, Aug 02, 2014 at 03:33:37PM -0700, David Miller wrote: > From: Wei Liu <wei.l...@citrix.com> > Date: Fri, 1 Aug 2014 12:02:46 +0100 > > > On Thu, Jul 31, 2014 at 01:25:20PM -0700, David Miller wrote: > >> If you were to have a 64-slot TX queue, you ought to be able to handle > >> this theoretical 51 slot SKB. > > > > There's two problems: > > 1. IIRC a single page ring has 256 slots, allowing 64 slots packet > > yields 4 in-flight packets in worst case. > > 2. Older netback could not handle this large number of slots and it's > > likely to deem the frontend malicious. > > > > For #1, we don't actually care that much if guest screws itself by > > generating 64 slot packets. #2 is more concerning. > > How many slots can the older netback handle?
I listed those two problems in the context "if we were to lift this limit in the latest net-next tree", so "older netback" actually refers to netback from 3.10 to 3.16. The current implementation allows the number of slots X: 1. X <= 18, valid packet 2. 18 < X < fatal_slot_count, dropped 3. X >= fatal_slot_count, malicious frontend fatal_slot_count has default value of 20. Wei. > -- > To unsubscribe from this list: send the line "unsubscribe netdev" in > the body of a message to majord...@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- 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/
