taglinefilesource code
ip_rjiffies350drivers/net/ppp.cppp->ddinfo.ip_rjiffies  =
ip_rjiffies1039drivers/net/ppp.cppp->ddinfo.ip_rjiffies = jiffies;
ip_rjiffies1525drivers/net/ppp.ccur_ddinfo.ip_rjiffies  = cur_jiffies - ppp->ddinfo.ip_rjiffies;
ip_rjiffies160include/linux/ppp.hunsigned long    ip_rjiffies;  /* time when last IP frame recvd*/