CONFIG_NET_CLS (not configurable)

modulename: cls_api.ko

configname: CONFIG_NET_CLS

Linux Kernel Configuration
└─>Networking support
└─>Networking options
└─>QoS and/or fair queueing
└─>NET_CLS
In linux kernel since version 2.6.12  
source code:
net/sched//cls_api.c