+ OVS_GREP_IFELSE([$KSRC26/include/net/checksum.h], [csum_unfold],
+ [OVS_DEFINE([HAVE_CSUM_UNFOLD])])
+ OVS_GREP_IFELSE([$KSRC26/include/linux/skbuff.h], [skb_cow],
+ [OVS_DEFINE([HAVE_SKB_COW])])
+ # Check for the proto_data_valid member in struct sk_buff. The [^@]
+ # is necessary because some versions of this header remove the
+ # member but retain the kerneldoc comment that describes it (which
+ # starts with @). The brackets must be doubled because of m4
+ # quoting rules.
+ OVS_GREP_IFELSE([$KSRC26/include/linux/skbuff.h], [[[^@]]proto_data_valid],
+ [OVS_DEFINE([HAVE_PROTO_DATA_VALID])])