Re: [PATCH net-next V2] net/vxlan: Avoid unaligned access in vxlan_build_skb()

On 21.09.2016 18:14, Alexei Starovoitov wrote:

On Wed, Sep 21, 2016 at 12:10:55PM +0200, Hannes Frederic Sowa wrote:

quoted

On 20.09.2016 20:57, Sowmini Varadhan wrote:

quoted

The vxlan header may not be aligned to 4 bytes in
vxlan_build_skb (e.g., for MLD packets). This patch
avoids unaligned access traps from vxlan_build_skb
(in platforms like sparc) by making struct vxlanhdr __packed.

Signed-off-by: Sowmini Varadhan <redacted>

Performance wise this should only affect code generation for archs where
it matters anyway.

I think it's the opposite. Even on x86 compiler will use byte loads.

I checked that on x86-64 actually. Also clearly visible here:

https://godbolt.org/g/xsW2P1

Bye,
Hannes