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SubjectRe: [PATCH] coccinelle: api: add vma_pages.cocci


On Sun, 17 May 2015, Dmitry Kalinkin wrote:

> This semantic patch replaces explicit computations of vma page count
> with explicit function call.

Thanks!

> Signed-off-by: Dmitry Kalinkin <dmitry.kalinkin@gmail.com>
> ---
> scripts/coccinelle/api/vma_pages.cocci | 66 ++++++++++++++++++++++++++++++++++
> 1 file changed, 66 insertions(+)
> create mode 100644 scripts/coccinelle/api/vma_pages.cocci
>
> diff --git a/scripts/coccinelle/api/vma_pages.cocci b/scripts/coccinelle/api/vma_pages.cocci
> new file mode 100644
> index 0000000..2b7a748
> --- /dev/null
> +++ b/scripts/coccinelle/api/vma_pages.cocci
> @@ -0,0 +1,66 @@
> +/// Use vma_pages function on vma object instead of explicit computation.

Add an extra /// here.

> +// Confidence: High
> +// Keywords: vma_pages vma
> +
> +// Based on resource_size.cocci
> +
> +virtual context
> +virtual patch
> +virtual org
> +virtual report
> +
> +//----------------------------------------------------------
> +// For context mode
> +//----------------------------------------------------------
> +
> +@r_context depends on context && !patch && !org@

Add && !report here

> +struct vm_area_struct *vma;
> +@@
> +
> +* (vma->vm_end - vma->vm_start) >> PAGE_SHIFT
> +
> +//----------------------------------------------------------
> +// For patch mode
> +//----------------------------------------------------------
> +
> +@r_patch1 depends on !context && patch && !org@

Add && !report here

> +struct vm_area_struct *vma;
> +@@
> +
> +- ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT)
> ++ vma_pages(vma)
> +
> +@r_patch2 depends on !context && patch && !org@
> +struct vm_area_struct *vma;
> +@@
> +
> +- (vma->vm_end - vma->vm_start) >> PAGE_SHIFT
> ++ vma_pages(vma)

This rule is not needed. An isomorphism will allow tha case with ()
around the whole thing to match the case where those parentheses are
absent.

> +//----------------------------------------------------------
> +// For org mode
> +//----------------------------------------------------------
> +
> +@r_org depends on !context && !patch && (org || report)@
> +struct vm_area_struct *vma;
> +position p;
> +@@
> +
> + (vma->vm_end@p - vma->vm_start) >> PAGE_SHIFT
> +
> +@script:python depends on report@
> +p << r_org.p;
> +x << r_org.vma;
> +@@
> +
> +msg="ERROR: Missing vma_pages with %s" % (x)

I think that the message is a bit misleading. Something like Use
vma_pages would be better.

> +coccilib.report.print_report(p[0], msg)
> +
> +@script:python depends on org@
> +p << r_org.p;
> +x << r_org.vma;
> +@@
> +
> +msg="ERROR with %s" % (x)
> +msg_safe=msg.replace("[","@(").replace("]",")")
> +coccilib.org.print_todo(p[0], msg_safe)

The message could be the same in this case as in the previous one.

It may be good to put below the keywords:

// Comments:
// Options: --all-includes

This rule relies on type information, ie knowing whether something has
type struct vm_area_struct *, so having more include files available may
make that more apparent. On the other hand, if you think the referenced
thing will always be a local variable (as opposed to a structure field),
then just using the current C file should be good enough, and it will be
faster without the --all-includes option.

I tried the rule replacing struct vm_area_struct *vma; by expression vma
and got a couple of results on other types. One could wonder if that code
could be improved in some way.

julia


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