Re: [Outreachy kernel] Coccinelle Constification

[Elizabeth Ferdman <gnudevliz@gmail.com>]

On Sun, Oct 16, 2016 at 11:04:20AM +0800, Eva Rachel Retuya wrote:
> Hello Liz,
> 
> I'm a fellow applicant so I might be wrong on some things but let me
> share my experience so far with coccinelle usage.
> 
> On Sat, Oct 15, 2016 at 07:21:46PM -0700, Elizabeth Ferdman wrote:
> > I'd like to try doing constification using Coccinelle but I'm having
> > trouble starting on this task. Bhumika Goyal has submitted lots of these
> > and I've looked at the scripts she uses but I'm very confused about the
> > process.
> > 
> > Do you identify the structs that
> > need to be const first, then write the cocci script? If not, then what
> > is a basic script to use to find structs that need to be const? I can't
> > find any specific documentation that pertains to constification and
> > coccinelle.
> > 
> 
> It depends on your approach. Sure you can manually identify by code
> tracing if the struct qualifies to be made const then make a script to
> write the changes esp. if there are lots of places to be changed.
> 
> You can also define a set of properties/situations where declaring the
> structure const is justified like this:
> https://git.kernel.org/cgit/linux/kernel/git/gregkh/staging.git/commit/drivers/staging?h=staging-testing&id=1c099ed63f8363228a0b075a25511c9feb90e03f
> 
Hey Eva,

Thanks so much for your reply and thanks for this link. That criteria is
very helpful esp because I'm a beginner in C and that clears up more of
what was going on in the long cocci script. It's a good idea to search
in greg's staging tree-- I had just been searching inside the
outreachy mailing list for the most part.

Liz

> and from there write your script so that it'll detect instances where
> the criteria you previously defined is met. Now that covers detection,
> for making the changes I suggest you write another one to cater
> specifically to a specific driver and also include the transformation
> that needs to be done.
> 
> About the basic script, I suggest you try to match any struct
> declaration first using the disable optional_qualifier isomorphism
> stated on the project's small task 1. Start small then build your way
> up.
> 
> Once you get your basic script running, coordinate the rest with Julia.
> Bhumika's patches are great reference, just observe the 'criteria' at
> which structures can be deemed 'const'.
> 
> I hope I clear some of your confusion,
> Eva
> 
> > Thanks,
> > Liz
> > 
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