On Tue, 15 Nov 2016, Reshetova, Elena wrote:
>
> Good day,
>
>
>
> I am very new to coccinelle, and therefore my question is rather basic, but
> unfortunately I wasn’t able to find the info online.
>
> I have a very simple cocci rule:
>
>
>
> ------------------------------
>
>
>
> @r exists@
> identifier a;
> identifier x;
> position p1, p2;
> @@
>
> atomic_dec_and_test(&a->x)@p1
> ...
> kfree(a)@p2;
>
> @script:python@
> p1 << r.p1;
> p2 << r.p2;
> @@
>
> print "* file: %s atomic_dec_and_test %s before kfree %s" %
> (p1[0].file,p1[0].line,p2[0].line)
>
>
>
> --------------------------------
>
>
>
> I just want to find all occurrences of atomic_dec_and_test(), which are
> somewhere later in the code flow (maybe called using some intermediate
> function, such as kfree_rcu() or others) followed by kfree() on the same
> pointer.
>
>
>
> When this rule is applied to Linux kernel tree, it results in 80 of such
> occurrences found. However, the output is a bit confusing. For example:
>
>
>
> …
>
> Skipping:./linux-stable/kernel/rcu/srcu.c
> Skipping:./linux-stable/kernel/rcu/rcuperf.c
> Skipping:./linux-stable/kernel/rcu/waketorture.c
> HANDLING: ./linux-stable/kernel/rcu/rcutorture.c
> Skipping:./linux-stable/kernel/rcu/update.c
> Skipping:./linux-stable/kernel/rcu/tree.c
> Skipping:./linux-stable/kernel/panic.c
> Skipping:./linux-stable/kernel/utsname.c
> Skipping:./linux-stable/kernel/cgroup_freezer.c
> HANDLING: ./linux-stable/kernel/workqueue.c
> HANDLING: ./linux-stable/kernel/cgroup.c
>
> ….
>
>
>
> I understand that “Skipping” means that the pattern was not found in that .c
> file. But what does “HANDLING” actually mean?
>
> There are 330 of such “HANDLING” happen with above rule and when I manually
> check some of them, for example linux-stable/kernel/cgroup.c, it is actually
> the correct case that I want to be found, and it seems to be “HANDLED”, but
> not reported.
You need to separate standard output and standard error. Skipping and
HANDLING indicate just that the file is totaly irrelevant and so ignored
(Skipping) or possibly relevant and thus parsed and matched against your
rule (HANDLING). This is just useful for checking that Coccinelle is
progressing. You may also see information about cases that run for a long
time. This is all on standard error. The results from your print
statements will be on standard output.
julia
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