Re: [PATCH] trace: Fix some checker warnings

[Masami Hiramatsu (Google) <mhiramat@kernel.org>]

On Sun, 4 Dec 2022 21:39:29 -0500
Steven Rostedt <rostedt@goodmis.org> wrote:

> On Mon, 5 Dec 2022 11:22:36 +0900
> Masami Hiramatsu (Google) <mhiramat@kernel.org> wrote:
> 
> > diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
> > index 5cfc95a52bc3..14f18edfe5bc 100644
> > --- a/kernel/trace/trace.c
> > +++ b/kernel/trace/trace.c
> > @@ -6572,7 +6572,8 @@ tracing_thresh_write(struct file *filp, const char __user *ubuf,
> >  	return ret;
> >  }
> >  
> > -#if defined(CONFIG_TRACER_MAX_TRACE) || defined(CONFIG_HWLAT_TRACER)
> > +#if defined(CONFIG_TRACER_MAX_TRACE) || defined(CONFIG_HWLAT_TRACER) \
> > +	|| defined(CONFIG_OSNOISE_TRACER)
> >  
> 
> When it gets this much, we need to put it into the trace.h header and
> define it. Actually, we have something that handles this too.
> 
> #if (defined(CONFIG_TRACER_MAX_TRACE) || defined(CONFIG_HWLAT_TRACER) \
>         || defined(CONFIG_OSNOISE_TRACER)) && defined(CONFIG_FSNOTIFY)
> #define LATENCY_FS_NOTIFY
> #endif
> 
> 
> We can add:
> 
>  #if (defined(CONFIG_TRACER_MAX_TRACE) || defined(CONFIG_HWLAT_TRACER) \
> 	|| defined(CONFIG_OSNOISE_TRACER)) && defined(CONFIG_FSNOTIFY)
>  #define LATENCY_FS_NOTIFY
> +#define USES_MAX_TRACE
>  #endif

No, that including defined(CONFIG_FSNOTIFY) :)

So it must be something like 

  #if defined(CONFIG_TRACER_MAX_TRACE) || defined(CONFIG_HWLAT_TRACER) \
          || defined(CONFIG_OSNOISE_TRACER)
  #define USE_MAX_TRACE_OPS
  #endif

  #if defined(USE_MAX_TRACE_OPS) && defined(CONFIG_FSNOTIFY)
  #define LATENCY_FS_NOTIFY
  #endif


But this introduces a hidden dependency which is not tracked by
kconfig. So I think it is better to make those kconfig (non-menu)
items. (and the question came up, why can't those use (depend on)
CONFIG_TRACER_MAX_TRACE instead of introducing the USE_MAX_TRACE_OPS.)

Thank you,

-- 
Masami Hiramatsu (Google) <mhiramat@kernel.org>