Re: [PATCH v3 3/5] tracing: Use __free() for kprobe events to cleanup

[Google]

On Tue, 7 Jan 2025 10:42:31 -0500
Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:

> On Tue,  7 Jan 2025 20:50:35 +0900
> "Masami Hiramatsu (Google)" <mhiramat@xxxxxxxxxx> wrote:
> 
> > @@ -1898,7 +1899,8 @@ create_local_trace_kprobe(char *func, void *addr, unsigned long offs,
> >  			  bool is_return)
> >  {
> >  	enum probe_print_type ptype;
> > -	struct trace_kprobe *tk;
> > +	struct trace_kprobe *tk __free(free_trace_kprobe) = NULL;
> > +	struct trace_probe *tp;
> >  	int ret;
> >  	char *event;
> >  
> > @@ -1929,19 +1931,16 @@ create_local_trace_kprobe(char *func, void *addr, unsigned long offs,
> >  
> >  	ptype = trace_kprobe_is_return(tk) ?
> >  		PROBE_PRINT_RETURN : PROBE_PRINT_NORMAL;
> > -	if (traceprobe_set_print_fmt(&tk->tp, ptype) < 0) {
> > -		ret = -ENOMEM;
> > -		goto error;
> > -	}
> > +	if (traceprobe_set_print_fmt(&tk->tp, ptype) < 0)
> > +		return ERR_PTR(-ENOMEM);
> >  
> >  	ret = __register_trace_kprobe(tk);
> >  	if (ret < 0)
> > -		goto error;
> > +		return ERR_PTR(ret);
> >  
> > -	return trace_probe_event_call(&tk->tp);
> > -error:
> > -	free_trace_kprobe(tk);
> > -	return ERR_PTR(ret);
> 
> 
> > +	tp = &tk->tp;
> > +	tk = NULL;	/* 'tk' is registered successfully, so do not free. */
> 
> I wonder if we could change the above to just:
> 
> 	tp = &(no_free_ptr(tk)->tp);

Ah, that's nice idea. Then I can remove 'tp' as;

	return trace_probe_event_call(&(no_free_ptr(tk)->tp));

Thanks!

> 
> ?
> 
> -- Steve
> 
> > +	return trace_probe_event_call(tp);
> >  }
> >  
> >  void destroy_local_trace_kprobe(struct trace_event_call *event_call)
> 


-- 
Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>