[Cocci] Replacing one (specific!) type with another

[julia.lawall@lip6.fr (Julia Lawall)]

On Mon, 10 Oct 2016, Nikolaus Rath wrote:

> On Oct 10 2016, Julia Lawall <julia.lawall@lip6.fr> wrote:
> >> Ok, we're getting there. I've removed the second 'symbol' line, and
> >> (permanently) updated to 1.0.6. However, now it seems to simply run
> >> forever:
> >>
> >> $ ../coccinelle-1.0.6/spatch.opt --sp-file
> >> ~/in-progress/libfuse/se-rename.cocci --in-place lib/ include/ test/
> >> example/ util/
> >> init_defs_builtins: /home/nikratio/tmp/coccinelle-1.0.6/standard.h
> >> warning: patch output can only be created when only one
> >> directory is specified or when the -patch flag is used
> >> HANDLING: lib/fuse.c
> >> (ONCE) Expected tokens fuse_session f
> >> Skipping:lib/fuse_opt.c
> >> HANDLING: lib/helper.c
> >> Skipping:lib/mount_bsd.c
> >> Skipping:lib/fuse_loop_mt.c
> >> Skipping:lib/fuse_loop.c
> >> HANDLING: lib/cuse_lowlevel.c
> >> diff =
> >> [...]
> >> HANDLING: lib/fuse_lowlevel.c
> >>
> >> At this point it has been hanging for about 15 minutes now, steady
> >> eating CPU time.
> >>
> >> Is it supposed to take that long? The fuse_lowlevel.c file is 74k with
> >> 2465 lines of code.
> >
> > You can use --show-trying to see what function it is getting stuck on.  If
> > the function has a lot of ifs and loops, it may indeed take a long
> > time.  ... follows possible paths in the execution graph and a sequence of
> > ifs makes the number of paths grow exponentially.
> >
> > A solution is to add a timeout, eg --timeout 120 (120 seconds).  You will
> > need to check a file on which there is a timeout manually.
> >
> > Tracing paths around loops is not really relevant in your case, so you can
> > also safely use the option --no-loops, which will avoid taking the back
> > edges.
>
> I tried doing both, but it still gets stuck:
>
> init_defs_builtins: /home/nikratio/tmp/coccinelle-1.0.6/standard.h
> HANDLING: lib/fuse_lowlevel.c
> -----------------------------------------------------------------------
> rule starting on line 1 =
> -----------------------------------------------------------------------
> [...]
> -----------------------------------------------------------------------
> rule starting on line 13 =
> -----------------------------------------------------------------------
> [...]
>    trying function: do_init: fuse_lowlevel.c:1812
>
>
> The do_init() function doesn't seem all that terrible to me though:
> https://github.com/libfuse/libfuse/blob/58273972f0b20/lib/fuse_lowlevel.c#L1812

Yes it does.  Look at lines 1852-1877.  There are 2^13 execution paths
there, and there is another such stack of ifs later in the function.

So you did add a timeout and it is still getting stuck?  Try a very short
timeout just to see what happens.

julia