trace_array_get_by_name
qla_trc_array = trace_array_get_by_name("qla2xxx", NULL);
struct trace_array *trace_array_get_by_name(const char *name, const char *systems);
backup_tr = trace_array_get_by_name(backup, NULL);
EXPORT_SYMBOL_GPL(trace_array_get_by_name);
tr = trace_array_get_by_name(p, NULL);
tr = trace_array_get_by_name("sample-instance", "sched,timer,kprobes");