On (09/20/16 18:11), Jiri Benc wrote: > > The vxlan header is at offset (14 + 20 + 8) into the packet, > > so the vxh is not aligned in vxlan_build_skb. Use [get/put]_unaligned > > functions to modify flags and vni field in the vxh. > > How did you calculate that? IP header should be aligned to 4 bytes, UDP > header is 8 bytes, thus VXLAN header is also aligned to 4 bytes.
The vxlan header is after the ethernet header (14 bytes), IP header (20 bytes, assuming no options) and udp header (8 bytes). Post the skb_reserve adjustments (see computations in in mld_newpack(), for example), this triggers an unaligned access on sparc. > If you went this way, it would be better to make two local variables > for vx_flags and vx_vni, store to them and do a single put_unaligned > after the condition. That way, you would have two less put_unaligned and > no get_unaligned in the remote csum case. Ok, that is certainly possible. > And the code would be > cleaner. And you're missing vx_flags being accessed in > vxlan_build_gbp_hdr. Sure, and there's also potential unaligned access in vxlan_build_gpe_hdr. But as I was telling Tom, this problem is much deeper than this fix, and I dont have the facility, at the moment, to test out every one of these code paths. We would have to fix these, one at a time, in subsequent patches. This one just fixes the top-level basic code paths. > But I think this is not needed at all, see above. > > Jiri
