Symbol: blk_add_trace_zone_unplug
kernel/trace/blktrace.c
1357
ret = register_trace_blk_zone_wplug_bio(blk_add_trace_zone_unplug,
kernel/trace/blktrace.c
1379
unregister_trace_blk_zone_wplug_bio(blk_add_trace_zone_unplug, NULL);