[Cocci] RFC - simple scanners and matching macros

[der.herr@hofr.at (Nicholas Mc Guire)]

On Tue, 23 Dec 2014, Julia Lawall wrote:

> > > > first working case:
> > > > ===================
> > > >
> > > > @c@
> > > > expression cmp;
> > > > position p;
> > > > @@
> > > >
> > > >  init_completion at p(cmp)
> > > >
> > > > @d@
> > > > expression E,c.cmp;
> > > > identifier f;
> > > > position c.p,p1;
> > > > @@
> > > >
> > > >   init_completion at p(cmp)
> > > >   ...
> > > > (
> > > >   E = cmp
> > > > |
> > > >   E = &cmp
> > > > |
> > > >   f(..., cmp,...)
> > > > |
> > > >   f(..., &cmp,...)
> > > > )
> > > >   ...
> > >
> > > Perhaps you want <+... ...+> here, if these assignments or function calls
> > > could occur more than once?
> >
> > fixed.
> >
> > >
> > > > - init_completion at p1(cmp)
> > > > + reinit_completion1(cmp)
> > > >
> > > >
> > > > 2nd working case:
> > > > =================
> > > >
> > > > @c@
> > > > expression cmp;
> > > > position p;
> > > > @@
> > > >
> > > >  init_completion at p(cmp)
> > > >
> > > > @d@
> > > > expression E,c.cmp;
> > > > identifier f;
> > > > position c.p,p1;
> > > > @@
> > > >
> > > >   init_completion at p(cmp)
> > > >   ... when != E = cmp
> > > >       when != E = &cmp
> > > >       when != f(..., cmp,...)
> > > >       when != f(..., &cmp,...)
> > > > - init_completion at p1(cmp);
> > >
> > > OK.  If you allow there to be none of these calls in between, then you
> > > could merge these two rules, and change <+... ...+> to <... ...>.  But I
> > > am not really sure what is the goal of these constraints at all.  Why not
> > > just:
> > >
> > > init_completion at p(cmp)
> > > ...
> > > init_completion at p1(cmp)
> > >
> >
> > because that would match cases like
> >
> >  init_completion(cmp)
> >  wait_for_completion(cmp)
> >  init_completion(cmp)
> 
> Doesn't this match the "first working case" rule?
>

yes - just not sure if the first case is exhaustive - only
if it is would the second rule in the simplified version
be correct I believe. 

> > and that is not a double init but a reinit
> > So the intent of the construct is to catch
> > cases like:
> >
> > +++ b/drivers/scsi/qla4xxx/ql4_os.c
> > @@ -8672,7 +8672,6 @@ static int qla4xxx_probe_adapter(struct
> >         init_completion(&ha->disable_acb_comp);
> >         init_completion(&ha->idc_comp);
> >         init_completion(&ha->link_up_comp);
> > -       init_completion(&ha->disable_acb_comp);
> >
> > where nothing was done with the completion object between the
> > calls - so this should not be changed to a reinit_completion but dropped.
> >
> > > >
> > > > the not-working case:
> > > > =====================
> > > > @e@
> > > > expression cmp;
> > > > identifier f;
> > > > position p;
> > > > @@
> > > >
> > > > f(...) {
> > > >   ...
> > > > - DECLARE_COMPLETION at p(cmp);
> > > > + DECLARE_COMPLETION_ONSTACK(cmp);
> > > >   ...
> > > > }
> > >
> > > You need to add
> > >
> > > declarer name DECLARE_COMPLETION;
> > >
> > > among the metavariables.
> > >
> > tried it as you suggested - but that fusses:
> >
> > hofrat at debian:/tmp/linux-next$ make coccicheck COCCI=false_declare_completion.cocci MODE=patch
> >
> > Fatal error: exception Failure("meta: parse error:
> >  = File "false_declare_completion.cocci", line 15, column 0,  charpos = 295
> >     around = 'declare', whole content = declare name DECLARE_COMPLETION;
> > ")
> 
> declarer name, with an "r" a the end, not declare name.
>

tried that first then removed the r assuming it was a typo

hofrat at debian:~/git/linux-next$ make coccicheck COCCI=false_declare_completion.cocci MODE=report

Please check for false positives in the output before submitting a patch.
When using "patch" mode, carefully review the patch before submitting it.

297 298
Fatal error: exception Failure("meta: parse error: 
 = File "false_declare_completion.cocci", line 14, column 32,  charpos = 297
    around = '@', whole content = declarer name DECLARE_COMPLETION@;
")

same for MODE=patch
 
> >
> > spatch version is
> > hofrat at debian:/tmp/linux-next$ spatch --version
> > spatch version 1.0.0-rc21 with Python support and with Str regexp support
> >
> > The complete cocci script is below
> >
> > /* check for incorrect DECLARE_COMPLETION use within a function
> >  *
> >  * Options: --no-includes  --include-headers
> >  */
> > virtual context
> > virtual patch
> > virtual org
> > virtual report
> >
> > /* flag incorrect initializer*/
> > @e depends on patch && !(context || org || report)@
> > expression cmp;
> > identifier f;
> > declare name DECLARE_COMPLETION;
> > position p;
> > @@
> >
> > f(...) {
> >   ...
> > - DECLARE_COMPLETION at p(cmp);
> > + DECLARE_COMPLETION_ONSTACK(cmp);
> >   ...
> 
> Actually, there should be <... ...> here too.  Otherwise, you will allow
> only one DECLARE_COMPLETION in the function.
> 
> > }
> >
> > @ep depends on !patch && (context || org || report)@
> > expression cmp;
> > identifier f;
> > declare name DECLARE_COMPLETION;
> > position p;
> > @@
> >
> > f(...) {
> >   ...
> > * DECLARE_COMPLETION at p(cmp);
> >   ...
> > }
> 
> Same here.
>
thanks fixed this as well.

thx!
hofrat