linux-kernel - Re: [PATCH 2/2] trace-cmd: replace show_file() -> show_instance

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Date:   Mon, 10 Jul 2017 02:15:35 +0200
From:   Federico Vaga <federico.vaga@...a.pv.it>
To:     Steven Rostedt <rostedt@...dmis.org>
Cc:     LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/2] trace-cmd: replace show_file() -> show_instance_file()

On Friday, July 7, 2017 12:29:35 AM CEST Steven Rostedt wrote:
> On Mon,  5 Jun 2017 11:31:18 +0200
> 
> Federico Vaga <federico.vaga@...a.pv.it> wrote:
> > show_file(name) and show_instance_file(&top_instance, name) are
> > equivalent.
> > 
> > Remove the show_file() function in order to have a single function for
> > this task.
> 
> Actually I find nothing wrong with having a helper function like this.
> IIRC, show_file() was first, and then show_instance_file() came later.
> There's some files that only exist for the top_instance, and I like the
> fact that this is annotated that way.
> 
> I'm curious to know what the benefit of removing show_file() is?

The show_file(name) and show_instance_file(&top_instance, name) are 
equivalent: they do the same thing. By removing `show_file` the developers are 
forced to use always the same function and being explicit about the instance 
they want to use.

The name `show_file()` is so generic that does not implies automatically that 
we are accessing the top_instance. This is not even clear by reading the 
implementation; people must read the other functions used in `show_file()` to 
understand that their instance scope is always 'top_instance'.

So, in my opinion, it makes the code easier to read and more explicit in what 
is doing without too much effort.

> -- Steve
> 
> > Signed-off-by: Federico Vaga <federico.vaga@...a.pv.it>
> > ---
> > 
> >  trace-list.c     | 21 ++++++---------------
> >  trace-local.h    |  2 --
> >  trace-show.c     | 18 ++----------------
> >  trace-snapshot.c |  2 +-
> >  4 files changed, 9 insertions(+), 34 deletions(-)
> 
> \

-- 
Federico Vaga
http://www.federicovaga.it/