__ftrace_trace_stack
__ftrace_trace_stack(tr, buffer, trace_ctx, skip, NULL);
__ftrace_trace_stack(tr, buffer, trace_ctx, skip, NULL);
__ftrace_trace_stack(printk_trace, printk_trace->array_buffer.buffer,
void __ftrace_trace_stack(struct trace_array *tr,
__ftrace_trace_stack(tr, buffer, trace_ctx, skip, regs);