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    Subject[PATCH] coccinelle: Add patch to use kcalloc instead of kzalloc for array allocations
    Date
    This patch adds a coccinelle patch to convert array allocations which use
    kzalloc to kcalloc. The advantage of kcalloc is, that will take care of
    integer overflows which could result from the multiplication and it is also
    nicer to read.

    The coccinelle patch does not convert array allocations using kmalloc, since
    kcalloc will zero the allocated memory which is considered too much overhead
    in some situations.

    Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
    ---
    scripts/coccinelle/api/alloc/kcalloc.cocci | 59 ++++++++++++++++++++++++++++
    1 files changed, 59 insertions(+), 0 deletions(-)
    create mode 100644 scripts/coccinelle/api/alloc/kcalloc.cocci

    diff --git a/scripts/coccinelle/api/alloc/kcalloc.cocci b/scripts/coccinelle/api/alloc/kcalloc.cocci
    new file mode 100644
    index 0000000..b2a5893
    --- /dev/null
    +++ b/scripts/coccinelle/api/alloc/kcalloc.cocci
    @@ -0,0 +1,59 @@
    +///
    +/// Use kcalloc instead of kzalloc to allocate array.
    +/// The advantage of kcalloc is, that will prevent integer overflows which could
    +/// result from the multiplication of number of elements and size and it is also
    +/// a bit nicer to read.
    +///
    +// Confidence: High
    +// Options: -no_includes -include_headers
    +//
    +// Keywords: kzalloc, kcalloc
    +// Version min: < 2.6.12 kcalloc
    +// Version min: 2.6.14 kzalloc
    +//
    +
    +virtual context
    +virtual patch
    +virtual org
    +virtual report
    +
    +//----------------------------------------------------------
    +// For patch mode
    +//----------------------------------------------------------
    +
    +@depends on patch@
    +expression E;
    +expression E2;
    +expression gfp;
    +expression x;
    +@@
    +-x = kzalloc(sizeof(E2) * (E), gfp);
    ++x = kcalloc(E, sizeof(E2), gfp);
    +
    +//----------------------------------------------------------
    +// For org and report mode
    +//----------------------------------------------------------
    +
    +@r depends on org || report@
    +expression E;
    +expression E2;
    +expression gfp;
    +position p;
    +expression x;
    +@@
    +x = kzalloc@p(sizeof(E2) * (E), gfp);
    +
    +@script:python depends on org@
    +p << r.p;
    +x << r.x;
    +@@
    +
    +coccilib.org.print_safe_todo(p[0], "%s" % x)
    +
    +@script:python depends on report@
    +p << r.p;
    +x << r.x;
    +@@
    +
    +msg="WARNING: kcalloc should be used to allocate an array instead of kzalloc"
    +coccilib.report.print_report(p[0], msg)
    --
    1.7.7.1



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