linux-kernel - Re: [PATCH] Coccinelle: add atomic_as

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Date:   Fri, 4 Aug 2017 17:23:03 +0200 (CEST)
From:   Julia Lawall <julia.lawall@...6.fr>
To:     Elena Reshetova <elena.reshetova@...el.com>
cc:     linux-kernel@...r.kernel.org, cocci@...teme.lip6.fr,
        Gilles Muller <Gilles.Muller@...6.fr>, nicolas.palix@...g.fr,
        mmarek@...e.com, keescook@...omium.org, ishkamiel@...il.com
Subject: Re: [PATCH] Coccinelle: add atomic_as_refcounter script



On Tue, 18 Jul 2017, Elena Reshetova wrote:

> atomic_as_refcounter.cocci script allows detecting
> cases when refcount_t type and API should be used
> instead of atomic_t.
>
> Signed-off-by: Elena Reshetova <elena.reshetova@...el.com>
> ---
>  scripts/coccinelle/api/atomic_as_refcounter.cocci | 102 ++++++++++++++++++++++
>  1 file changed, 102 insertions(+)
>  create mode 100644 scripts/coccinelle/api/atomic_as_refcounter.cocci
>
> diff --git a/scripts/coccinelle/api/atomic_as_refcounter.cocci b/scripts/coccinelle/api/atomic_as_refcounter.cocci
> new file mode 100644
> index 0000000..a16d395
> --- /dev/null
> +++ b/scripts/coccinelle/api/atomic_as_refcounter.cocci
> @@ -0,0 +1,102 @@
> +// Check if refcount_t type and API should be used
> +// instead of atomic_t type when dealing with refcounters
> +//
> +// Copyright (c) 2016-2017, Elena Reshetova, Intel Corporation
> +//
> +// Confidence: Moderate
> +// URL: http://coccinelle.lip6.fr/
> +// Options: --include-headers --very-quiet
> +
> +virtual report
> +
> +@r1 exists@
> +identifier a, x, y;
> +position p1, p2;
> +identifier fname =~ ".*free.*";
> +identifier fname2 =~ ".*destroy.*";
> +identifier fname3 =~ ".*del.*";
> +identifier fname4 =~ ".*queue_work.*";
> +identifier fname5 =~ ".*schedule_work.*";
> +identifier fname6 =~ ".*call_rcu.*";
> +
> +@@
> +
> +(
> + atomic_dec_and_test@p1(&(a)->x)
> +|
> + atomic_dec_and_lock@p1(&(a)->x, ...)
> +|
> + atomic_long_dec_and_lock@p1(&(a)->x, ...)
> +|
> + atomic_long_dec_and_test@p1(&(a)->x)
> +|
> + atomic64_dec_and_test@p1(&(a)->x)
> +|
> + local_dec_and_test@p1(&(a)->x)
> +)
> +...
> +?y=a

This makes the line optional. And if it dosn't appear, there is no
constraint on y.  So the rule matches:

int main() {
  atomic64_dec_and_test(&(a)->x);
  free(b);
}

I would suggest to just make two rules, one with y=a and one without.

julia

> +...
> +(
> + fname@p2(a, ...);
> +|
> + fname@p2(y, ...);
> +|
> + fname2@p2(...);
> +|
> + fname3@p2(...);
> +|
> + fname4@p2(...);
> +|
> + fname5@p2(...);
> +|
> + fname6@p2(...);
> +)
> +
> +
> +@...ipt:python depends on report@
> +p1 << r1.p1;
> +p2 << r1.p2;
> +@@
> +msg = "atomic_dec_and_test variation before object free at line %s."
> +coccilib.report.print_report(p1[0], msg % (p2[0].line))
> +
> +@r2 exists@
> +identifier a, x;
> +position p1;
> +@@
> +
> +(
> +atomic_add_unless(&(a)->x,-1,1)@p1
> +|
> +atomic_long_add_unless(&(a)->x,-1,1)@p1
> +|
> +atomic64_add_unless(&(a)->x,-1,1)@p1
> +)
> +
> +@...ipt:python depends on report@
> +p1 << r2.p1;
> +@@
> +msg = "atomic_add_unless"
> +coccilib.report.print_report(p1[0], msg)
> +
> +@r3 exists@
> +identifier x;
> +position p1;
> +@@
> +
> +(
> +x = atomic_add_return@p1(-1, ...);
> +|
> +x = atomic_long_add_return@p1(-1, ...);
> +|
> +x = atomic64_add_return@p1(-1, ...);
> +)
> +
> +@...ipt:python depends on report@
> +p1 << r3.p1;
> +@@
> +msg = "x = atomic_add_return(-1, ...)"
> +coccilib.report.print_report(p1[0], msg)
> +
> +
> --
> 2.7.4
>
>