Re: [Cocci] [PATCH v3 0/8] coccicheck: modernize

From: Julia Lawall
Date: Tue Jun 21 2016 - 17:03:49 EST


On Tue, 21 Jun 2016, Luis R. Rodriguez wrote:

> On Tue, Jun 21, 2016 at 10:13:31PM +0200, Julia Lawall wrote:
> >
> >
> > On Tue, 21 Jun 2016, Luis R. Rodriguez wrote:
> >
> > > This v3 series addresses the feedback from the last v2 series
> > > on the coccicheck enhancements [0], namely:
> > >
> > > o it drops the indexing heuristics in favor for a .cocciconfig use
> > > o drops glimpse support as its simply not well maintained, recommends
> > > idutils instead.
> > > o adds a Linux .cocciconfig -- the assumption is you'd run spatch when
> > > you're at the top level of the kernel. This has not only the side effect
> > > of picking up .cocciconfig, but also that the coccicheck use of the
> > > make variables passed on are assumed to be correct given the base
> > > directory as the current directory.
> >
> > I don't understand this point. Coccinelle picks up the .cocciconfig, if
> > any, of the directory on which you want to work, not of the current one.
>
> The order of precedence for variables for .coccoconfig is as follows:
>
> o Your current user's home directory is processed first
> o Your directory from which spatch is called is processed next
> o The directory provided with the --dir option is processed last, if used
>
> Since coccicheck runs through make, it naturally runs from the kernel proper
> dir, as such the second rule above would be implied for picking up a .cocciconfig.
> That's part of the point I'm making.

OK

> Up next let us consider when M= is used or when it is not used, if used
> it populates KBUILD_EXTMOD.
>
> if [ "$KBUILD_EXTMOD" = "" ] ; then
> OPTIONS="--dir $srctree $COCCIINCLUDE"
> else
> OPTIONS="--dir $KBUILD_EXTMOD $COCCIINCLUDE"
> fi
>
> Either way --dir is used, so the third rule applies and so your .cocciconfig
> from there is also read if one is found. My other point was that $COCCIINCLUDE
> has some useful tidbits of includes for coccinelle, and that also assumes
> one is on the top level dir of the kernel.

OK.

> That is sanitized as follows:
>
> # spatch only allows include directories with the syntax "-I include"
> # while gcc also allows "-Iinclude" and "-include include"
> COCCIINCLUDE=${LINUXINCLUDE//-I/-I }
> COCCIINCLUDE=${COCCIINCLUDE// -include/ --include}

I don't get the second case. Is it to replace -include by --include?
Coccinelle actually supports both, although it doesn't advertise that.

Also, in LINUXINCLUDE, what is the meaning of -include? For Coccinelle,
it is not the same as -I. It is for files that should be included that
are not in the set of includes seen by whatever is the specified include
strategy (--all-includes, etc). The argument is a specific file name, not
a directory. It is a way of eg not bothering with --recursive-includes
when there is one or a few key header files that each file will need.

> So the point is to annotate that the .cocconfig is picked up first due
> to the fact make is used and its issued from the top level makefile
> and starts from the top level. The fact that --dir is used is important
> but secondary to its introduction as well.

OK, the original text seemed to me to imply that running from the kernel
directory was essential to getting the kernels .cocciconfig, so I wanted
to point out that this is not the case.

julia