On Sun, 2016-01-31 at 13:37 -0800, Tom Herbert wrote: > Call get_unaligned_be32 when we access 32-bit fields in > __skb_flow_dissect. At the beginning check for unlikely case of > 1-byte aligned packet. > > Note that flow_dissector may be asked to parse packet unaligned > fields in two instances: > > 1) Packet from a driver which is aligned to Ethernet header > (2-byte alignment) > 2) Parsing inner headers of a received GRE-TEB packet > > Testing: Ran super_netperf tests did not see a regression. This was on > x86 which does not have problems with unaligned data.
But this test is absolutely useless, what about testing arches that actually care ? I am told all these MIPS based boxes have already not enough cpu power. It is sad, because none of them use the drivers that might call flow dissection (mlx4 and 4 intel drivers) So I would rather fix the cases where flow dissection called from eth_get_headlen() with non aligned stuff. And maybe restrict GRE-TEB to platforms with CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS=y, since otherwise we need to add these unaligned macros in thousands of places in our stacks.
