On Fri, Jan 29, 2016 at 12:01 PM, Eric Dumazet <eric.duma...@gmail.com> wrote: > On Fri, 2016-01-29 at 14:44 -0500, Sowmini Varadhan wrote: >> On (01/29/16 11:37), Eric Dumazet wrote: >> > >> > I have no idea why reading iph->saddr or iph->daddr would not hit the >> > problem, but accessing the 32bit ipv6 flow label would be an issue. >> > >> > Something is fishy. >> >> I was wondering about this myself. Even on sparc, I only first >> ran into the errors for ipv6. I dont know if the fact that the >> saddr is memcpy'ed masks the error (even though the problem >> is still there). > > Oh right, recent work in flow dissector added all these memcpy() > > I was still looking at linux-4.3 ;)
It has to be something recent. I know back when I wrote the code I tested it on a few different architectures and had to add a few bits in __skb_get_poff so that it would read doff as a u8 instead of bitfield in a u32. Looking at the code it seems like this should be an easy fix. Just swap the two lines that acquire and test the flow label with the check for dissector_uses_key(... _KEY_FLOW_LABEL). Then ixgbe will stop trying to grab flow labels. - Alex
