Re: [PATCH 4/5] x86/ftrace: Add annotations for ftrace_arch_code_modify_prepare() and ftrace_arch_code_modify_post_process()

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On Wed, 3 Jun 2020, Luc Van Oostenryck wrote:

> On Mon, Jun 01, 2020 at 03:46:47PM -0400, Steven Rostedt wrote:
> > On Mon,  1 Jun 2020 19:45:51 +0100
> > Jules Irenge <jbi.octave@xxxxxxxxx> wrote:
> >
> > > Sparse reports warnings
> > >
> > > warning: context imbalance in ftrace_arch_code_modify_prepare()
> > > 	- wrong count at exit
> > > warning: context imbalance in ftrace_arch_code_modify_post_process()
> > > 	- wrong count at exit
> > >
> > > The root cause is that even if
> > >  the annotations on the function are correct,
> > > mutex do not support annotation
>
> Yes.
>
> > Wait what? This looks like either a bug in sparse, or we just remove the
> > annotations. This just makes the code ugly, and looks silly.
>
> The annotations added by commit
>  074376ac0e1d ("ftrace/x86: Anotate text_mutex split between ...
> are indeed wrong (because they don't match what the functions are
> really doing / mutex operations have never been annotated).
> The're also pointless since their prototypes are un-annotated.

Interesting, I would think the best way would then be to remove the 
annotations. There are quite a number of them.

I will have to investigate more on mutex and annotation before moving 
forward.

Thanks for feedback.

Jules