# quoting rules.
OVS_GREP_IFELSE([$KSRC/include/linux/skbuff.h], [[[^@]]proto_data_valid],
[OVS_DEFINE([HAVE_PROTO_DATA_VALID])])
+ OVS_GREP_IFELSE([$KSRC/include/linux/skbuff.h], [skb_checksum_start_offset])
OVS_GREP_IFELSE([$KSRC/include/linux/skbuff.h], [kfree_skb_list])
OVS_GREP_IFELSE([$KSRC/include/linux/skbuff.h], [rxhash])
OVS_GREP_IFELSE([$KSRC/include/linux/skbuff.h], [u16.*rxhash],