Re: [PATCH v2 4/7] tracing: Add synthetic event error logging

[Tom Zanussi]

Hi Steve,

On Mon, 2020-10-12 at 17:49 -0400, Steven Rostedt wrote:
> On Mon, 12 Oct 2020 17:42:40 -0400
> Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:
> 
> > On Mon, 12 Oct 2020 15:18:06 -0500
> > Tom Zanussi <zanussi@xxxxxxxxxx> wrote:
> > 
> > > +static char last_cmd[MAX_FILTER_STR_VAL];
> > > +
> > > +static int errpos(const char *str)
> > > +{
> > > +	return err_pos(last_cmd, str);
> > > +}
> > > +
> > > +static void last_cmd_set(char *str)
> > > +{
> > > +	if (!str)
> > > +		return;
> > > +
> > > +	strncat(last_cmd, str, MAX_FILTER_STR_VAL - 1);  
> > 
> > If I understand strncat() correctly, it will add 'n' + 1 bytes from
> > str
> > to last_cmd. That is, I think you want:
> > 
> > 	strncat(last_cmd, str, MAX_FILTER_STR_VAL - (strlen(last_cmd) +
> > 1));
> > 
> 
> Looking at the patch more, it only has one caller to last_cmd_set(),
> and one caller to synth_err_clear().
> 
> Why not just clear on set?

Yeah, that would make sense, or just remove the clear and use strncpy
in last_cmd_set() instead.

Tom

> 
> -- Steve
> 
> 
> 
> > 
> > > +}
> > > +
> > > +static void synth_err(u8 err_type, u8 err_pos)
> > > +{
> > > +	tracing_log_err(NULL, "synthetic_events", last_cmd, err_text,
> > > +			err_type, err_pos);
> > > +}
> > > +
> > > +static void synth_err_clear(void)
> > > +{
> > > +	last_cmd[0] = '\0';
> > > +}
> > > +  
> 
>