Re: [RFC][PATCH] writeback: Unduplicate writeback reason

[Steven Rostedt <rostedt@goodmis.org>]

On Wed, 2011-12-14 at 09:49 +0800, Wu Fengguang wrote:
> Hi Steven,
> 
> On Wed, Dec 14, 2011 at 09:14:00AM +0800, Steven Rostedt wrote:
> > Names of the writeback reasons are used in both the main kernel as well
> > as for parsing the tracepoint format file. Instead of duplicating the
> > names in two locations making it likely that they may become out of
> > sync, use some macro magic to make sure all the names stay in sync. Any
> > update only needs to happen in one spot for it to take place in all
> > locations.
>  
> It looks a bit hacky,

One of my professors showed me this trick a long time ago when I was
going for my Masters. It was actually the trick I based the entire
TRACE_EVENT() macro magic on :)

>  but does the nice job of de-duplicating code.
> And it compiles. So I like it and would like to take it with the below
> rename :-)
> 
> > Note, this is an RFC patch, and it probably needs much better comments
> > (well, it currently has no comments), and the C() macro probably should
> > have a different name too.
> 
> C => WB_ENUM_REASONS_ITEM? It may look unpleasantly long, however is
> unique enough to make the many #define/#undef safe. 

Sure. Acked-by: Steven Rostedt <rostedt@goodmis.org>

Note, there's one buggy issue still. That the enums names still trip up
trace-cmd. But that's fine, because I have a plan to fix that too. But
that will be on the ftrace said.

Thanks!

-- Steve