[DCCP]: Introduces follows48 function

This adds a new function to see if two sequence numbers follow each
other.

Signed off by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: David S. Miller <davem@davemloft.net>

authored by Ian McDonald and committed by David S. Miller 837d107c e6bccd35

+8
+8
net/dccp/dccp.h
··· 81 81 return after48(seq1, seq2) ? seq1 : seq2; 82 82 } 83 83 84 + /* is seq1 next seqno after seq2 */ 85 + static inline int follows48(const u64 seq1, const u64 seq2) 86 + { 87 + int diff = (seq1 & 0xFFFF) - (seq2 & 0xFFFF); 88 + 89 + return diff==1; 90 + } 91 + 84 92 enum { 85 93 DCCP_MIB_NUM = 0, 86 94 DCCP_MIB_ACTIVEOPENS, /* ActiveOpens */