linux-kernel - Re: [PATCH] Coccinelle: Update and rename api/alloc/pci_free

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Date:   Sat, 26 Jun 2021 22:15:56 +0200 (CEST)
From:   Julia Lawall <julia.lawall@...ia.fr>
To:     Christophe JAILLET <christophe.jaillet@...adoo.fr>
cc:     Julia.Lawall@...ia.fr, Gilles.Muller@...ia.fr,
        nicolas.palix@...g.fr, michal.lkml@...kovi.net,
        cocci@...teme.lip6.fr, linux-kernel@...r.kernel.org,
        kernel-janitors@...r.kernel.org
Subject: Re: [PATCH] Coccinelle: Update and rename
 api/alloc/pci_free_consistent.cocci



On Wed, 16 Jun 2021, Christophe JAILLET wrote:

> 'pci_alloc_consistent()' is about to be removed from the kernel.
> It is now more useful to check for dma_alloc_coherent/dma_free_coherent.
>
> So change the script accordingly and rename it.

There also seem to be a lot of false positives, where the value is used in
unexpected ways, such as:

        for (i = 0; i < nr_pages; ++i) {
                cpu_addr = dma_alloc_coherent(dma_dev, PAGE_SIZE, &dma_addr,
                                              CIO_DMA_GFP);
                if (!cpu_addr)
                        return gp_dma;
                gen_pool_add_virt(gp_dma, (unsigned long) cpu_addr,
                                  dma_addr, PAGE_SIZE, -1);
        }

Maybe the rule should be dropped?

julia

>
> Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
> ---
> Not sure that the script works.
> There are 718 'dma_alloc_coherent' calls in 5.13-rc6. It is surprising
> to have no match at all, not even a single false positive.
> ---
>  ..._consistent.cocci => dma_free_coherent.cocci} | 16 ++++++++--------
>  1 file changed, 8 insertions(+), 8 deletions(-)
>  rename scripts/coccinelle/free/{pci_free_consistent.cocci => dma_free_coherent.cocci} (52%)
>
> diff --git a/scripts/coccinelle/free/pci_free_consistent.cocci b/scripts/coccinelle/free/dma_free_coherent.cocci
> similarity index 52%
> rename from scripts/coccinelle/free/pci_free_consistent.cocci
> rename to scripts/coccinelle/free/dma_free_coherent.cocci
> index d51e92556b42..75f159e7b6d7 100644
> --- a/scripts/coccinelle/free/pci_free_consistent.cocci
> +++ b/scripts/coccinelle/free/dma_free_coherent.cocci
> @@ -1,10 +1,10 @@
>  // SPDX-License-Identifier: GPL-2.0-only
> -/// Find missing pci_free_consistent for every pci_alloc_consistent.
> +/// Find missing dma_free_coherent for every dma_alloc_coherent.
>  ///
>  // Confidence: Moderate
>  // Copyright: (C) 2013 Petr Strnad.
>  // URL: http://coccinelle.lip6.fr/
> -// Keywords: pci_free_consistent, pci_alloc_consistent
> +// Keywords: dma_free_coherent, dma_alloc_coherent
>  // Options: --no-includes --include-headers
>
>  virtual report
> @@ -17,12 +17,12 @@ position p1,p2;
>  type T;
>  @@
>
> -id = pci_alloc_consistent@p1(x,y,&z)
> +id = dma_alloc_coherent@p1(x,y,&z)
>  ... when != e = id
>  if (id == NULL || ...) { ... return ...; }
> -... when != pci_free_consistent(x,y,id,z)
> -    when != if (id) { ... pci_free_consistent(x,y,id,z) ... }
> -    when != if (y) { ... pci_free_consistent(x,y,id,z) ... }
> +... when != dma_free_coherent(x,y,id,z)
> +    when != if (id) { ... dma_free_coherent(x,y,id,z) ... }
> +    when != if (y) { ... dma_free_coherent(x,y,id,z) ... }
>      when != e = (T)id
>      when exists
>  (
> @@ -40,7 +40,7 @@ p1 << search.p1;
>  p2 << search.p2;
>  @@
>
> -msg = "ERROR: missing pci_free_consistent; pci_alloc_consistent on line %s and return without freeing on line %s" % (p1[0].line,p2[0].line)
> +msg = "ERROR: missing dma_free_coherent; dma_alloc_coherent on line %s and return without freeing on line %s" % (p1[0].line,p2[0].line)
>  coccilib.report.print_report(p2[0],msg)
>
>  @script:python depends on org@
> @@ -48,6 +48,6 @@ p1 << search.p1;
>  p2 << search.p2;
>  @@
>
> -msg = "ERROR: missing pci_free_consistent; pci_alloc_consistent on line %s and return without freeing on line %s" % (p1[0].line,p2[0].line)
> +msg = "ERROR: missing dma_free_coherent; dma_alloc_coherent on line %s and return without freeing on line %s" % (p1[0].line,p2[0].line)
>  cocci.print_main(msg,p1)
>  cocci.print_secs("",p2)
> --
> 2.30.2
>
>