Re: [PATCH V7 1/3] tracing: add a possibility of exporting function trace to other places instead of ring buffer only

[Steven Rostedt]

On Tue, 15 Nov 2016 16:14:29 +0800
Chunyan Zhang <zhang.chunyan@xxxxxxxxxx> wrote:

>
> > Then why have a
> >
> >         if (export->write)
> >
> >
> > Is there every going to be a case where export will not have a write
> > function?  
> 
> There shouldn't be.
> 
> I can move this if statement to the register_ftrace_export() to ensure
> users won't wrongly use it, that's saying the write() of trace_export
> has been set before being registered to 'ftrace_exports_list'.
> 

Looks like it's already there:

+int register_ftrace_export(struct trace_export *export)
+{
+	if (WARN_ON_ONCE(!export->write))
+		return -1;


-- Steve