On Fri, 11 Nov 2016 15:49:41 +0300, Dan Carpenter wrote:
> Hello Jiri Benc,
>
> The patch 54bfd872bf16: "vxlan: keep flags and vni in network byte
> order" from Feb 16, 2016, leads to the following static checker
> warning:
>
> ./include/net/vxlan.h:340 vxlan_vni()
> warn: potential shift truncation. '0xffffff00 << 8'
>
> include/net/vxlan.h
> 335 static inline __be32 vxlan_vni(__be32 vni_field)
> 336 {
> 337 #if defined(__BIG_ENDIAN)
> 338 return (__force __be32)((__force u32)vni_field >> 8);
> 339 #else
> 340 return (__force __be32)((__force u32)(vni_field & VXLAN_VNI_MASK) << 8);
>
> Are you sure this is correct? VXLAN_VNI_MASK already has an << 8 shift
> so this feels like maybe it is a double shift.
The static checker clearly can't understand endian conversion macros.
VXLAN_VNI_MASK is:
cpu_to_be32(VXLAN_VID_MASK << 8)
Thus on little endian, it becomes 0x00ffffff.
Jiri
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