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Date:   Sat, 28 Mar 2020 15:00:00 +0100 (CET)
From:   Julia Lawall <julia.lawall@inria.fr>
To:     Markus Elfring <Markus.Elfring@web.de>
cc:     Michel Lespinasse <walken@google.com>,
        Coccinelle <cocci@systeme.lip6.fr>, linux-mm@kvack.org,
        Davidlohr Bueso <dave@stgolabs.net>,
        Peter Zijlstra <peterz@infradead.org>,
        Hugh Dickins <hughd@google.com>,
        LKML <linux-kernel@vger.kernel.org>,
        Liam Howlett <Liam.Howlett@oracle.com>,
        Jason Gunthorpe <jgg@ziepe.ca>,
        Matthew Wilcox <willy@infradead.org>,
        Ying Han <yinghan@google.com>,
        David Rientjes <rientjes@google.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Laurent Dufour <ldufour@linux.ibm.com>,
        Vlastimil Babka <vbabka@suse.cz>
Subject: Re: [Cocci] [v3 05/10] mmap locking API: Checking the Coccinelle
 software
In-Reply-To: <590dbec7-341a-3480-dd47-cb3c65b023c7@web.de>
Message-ID: <alpine.DEB.2.21.2003281459020.3005@hadrien>
References: <20200327225102.25061-1-walken@google.com> <20200327225102.25061-6-walken@google.com> <bc2980d7-b823-2fff-d29c-57dcbc9aaf27@web.de> <CANN689H=tjNi=g6M776qo8inr+OfAu8mtL5xsJpu4F=dB6R9zA@mail.gmail.com> <3c222f3c-c8e2-660a-a348-5f3583e7e036@web.de>
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> // deleted part
> retry:
> 	down_read(&mm->mmap_sem);
> 	vma = find_vma(mm, address);
> 	if (!vma)
> 		goto bad_area;
> // deleted part
> }
> // deleted part
>
>
> Application of the software “Coccinelle 1.0.8-00029-ga549b9f0” (OCaml 4.10.0)
>
> elfring@Sonne:~/Projekte/Coccinelle/Probe> spatch --parse-c do_page_fault-excerpt3.c
> …
> NB total files = 1; perfect = 1; pbs = 0; timeout = 0; =========> 100%
> nb good = 15,  nb passed = 1 =========> 6.25% passed
> nb good = 15,  nb bad = 0 =========> 100.00% good or passed
>
>
> The discussed transformation approach can also be reduced for a test
> to the following script for the semantic patch language.
>
> @replacement@
> expression x;
> @@
> -down_read
> +mmap_read_lock
>  (
> - &
>   x
> - ->mmap_sem
>  )
>
>
> elfring@Sonne:~/Projekte/Coccinelle/Probe> spatch use_mmap_locking_API_3.cocci do_page_fault-excerpt3.c
>
>
> The desired diff is not generated so far.
> How would you like to fix this situation?

The problem can be seen with the --debug option:

FLOW: can't jump to VMALLOC_FAULT_TARGET: because we can't find this label

It's not apparent with the --parse-c option because it's not a parsing
problem.

julia
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