coccinelle

[Nicholas Mc Guire]

On Tue, Mar 14, 2017 at 06:21:06PM +1100, Tobin C. Harding wrote:
> Attempting to do transform using Coccinelle
> 
> if (foo != 0) {
>    ...
> 
> ->
> 
> if (foo) {
>    ...
> 
> Coccinelle script attempt does not work
> 
> @@ expression x; @@
> (
> - x != 0
> + x
> )

I think you do not need the () here as you only are providing one semanntic patch
the only thing that was missing is the virtual rule - so using this simple spatch
file works for me 

<snip>
virtual patch

@tonull@
expression x;
@@

- x != 0
+ x
<snip>

hofrat at debian01:~/git/linux-next$ spatch --sp-file x.cocci --dir kernel/ | more
init_defs_builtins: /usr/local/lib/coccinelle/standard.h
no inferred keywords
HANDLING: kernel/sched/cpudeadline.c
diff = 
HANDLING: kernel/sched/swait.c
diff -u -p a/sched/cpudeadline.c b/sched/cpudeadline.c
--- a/sched/cpudeadline.c
+++ b/sched/cpudeadline.c
@@ -80,7 +80,7 @@ static void cpudl_heapify_up(struct cpud
        int orig_cpu = cp->elements[idx].cpu;
        u64 orig_dl = cp->elements[idx].dl;
 
-       if (idx == 0)
+       if (!idx)
                return;
....


> 
> `spatch --parse-cocci script.cocci` appears to pass. A similar script
> worked correctly
> 
> @@ expression x; @@
> (
> - x == 0
> + !x
> )

likewise

<snip>
virtual patch

@tontnull@
expression x;
@@

- x == 0
+ !x
<snip>

Using: spatch --version
spatch version 1.0.6-00033-g23cca0a compiled with OCaml version 4.0
.0
Flags passed to the configure script: [none]
Python scripting support: yes
Syntax of regular expresssions: PCRE


> 
> I have read various papers and tutorials to no avail. I have tried
> various other versions also with no success.
> 
> Any pointers most appreciated.
>
first you might want to read through the myriads of examples that
come with coccinelle in the kernel:
scripts/coccinelle/*
Documentation/dev-tools/coccinelle.rst

as well as the documentation in coccinelle repository:
URL: https://github.com/coccinelle/coccinelle 

And for specific technologies like semantic patches it is best to signeup
to the coccinelle mailing list and send such questions to
 Cocci at systeme.lip6.fr
archive at: https://systeme.lip6.fr/mailman/listinfo/cocci

thx!
hofrat