ifs_bits 60 include/uapi/linux/mroute6.h if_mask ifs_bits[__KERNEL_DIV_ROUND_UP(IF_SETSIZE, NIFBITS)]; ifs_bits 63 include/uapi/linux/mroute6.h #define IF_SET(n, p) ((p)->ifs_bits[(n)/NIFBITS] |= (1 << ((n) % NIFBITS))) ifs_bits 64 include/uapi/linux/mroute6.h #define IF_CLR(n, p) ((p)->ifs_bits[(n)/NIFBITS] &= ~(1 << ((n) % NIFBITS))) ifs_bits 65 include/uapi/linux/mroute6.h #define IF_ISSET(n, p) ((p)->ifs_bits[(n)/NIFBITS] & (1 << ((n) % NIFBITS)))