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Message-ID: <20150806133744.GB24253@opentech.at>
Date: Thu, 6 Aug 2015 15:37:44 +0200
From: Nicholas Mc Guire <der.herr@...r.at>
To: Andrzej Hajda <a.hajda@...sung.com>
Cc: Julia Lawall <Julia.Lawall@...6.fr>,
Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
linux-kernel@...r.kernel.org, Michal Marek <mmarek@...e.com>,
"moderated list:COCCINELLE/Semantic Patches SmPL"
<cocci@...teme.lip6.fr>,
Marek Szyprowski <m.szyprowski@...sung.com>
Subject: Re: [Cocci] [PATCH] coccinelle: memdup.cocci: fix matching rules
On Thu, 06 Aug 2015, Andrzej Hajda wrote:
> This patch fixes three things, listed in order of importance.
> 1. Removes matching of kmemdup from !patch rule - it is incorrect and
> in fact makes report mode unusable.
> 2. Adds unlikely to if clause. It allows to match more cases - the ones with
> unlikely and the ones without it.
> 3. Fixes report message.
>
> Signed-off-by: Andrzej Hajda <a.hajda@...sung.com>
> ---
> Hi Julia,
>
> I guess 1st and 3rd changes are OK. I am not sure about 2nd change, without
> it I was not able to catch cases containing unlikely macro. For example
> fs/ntfs/dir.c:1175:
> ir = kmalloc(rc, GFP_NOFS);
> if (unlikely(!ir)) {
> err = -ENOMEM;
> goto err_out;
> }
> /* Copy the index root value (it has been verified in read_inode). */
> memcpy(ir, (u8*)ctx->attr +
> le16_to_cpu(ctx->attr->data.resident.value_offset), rc);
>
> It seems quite strange for me, as these rules looks to me isomorphic.
> Is this expected behavior of coccinelle or just some bug?
>
> After this fix, cocci finds 46 places to patch, I will send patchset if this
> change looks OK to you.
>
> I have used:
> spatch version 1.0.1 with Python support and with PCRE support
> latest linux-next.
>
> Regards
> Andrzej
> ---
> scripts/coccinelle/api/memdup.cocci | 9 ++++-----
> 1 file changed, 4 insertions(+), 5 deletions(-)
>
> diff --git a/scripts/coccinelle/api/memdup.cocci b/scripts/coccinelle/api/memdup.cocci
> index 3d1aa71..2297205 100644
> --- a/scripts/coccinelle/api/memdup.cocci
> +++ b/scripts/coccinelle/api/memdup.cocci
> @@ -39,7 +39,7 @@ statement S;
>
> - to = \(kmalloc@p\|kzalloc@p\)(size,flag);
> + to = kmemdup(from,size,flag);
> - if (to==NULL || ...) S
> + if (unlikely(to==NULL) || ...) S
> - memcpy(to, from, size);
maybe I don't understand isomorphism declarations properly but
that should actually be covered by standard.iso:
@ unlikely @
expression E;
@@
unlikely(E) <=> likely(E) => E
??
so not clear why you would get more cases with this patch.
>
> @r depends on !patch@
> @@ -49,18 +49,17 @@ statement S;
> @@
>
> * to = \(kmalloc@p\|kzalloc@p\)(size,flag);
> - to = kmemdup(from,size,flag);
> - if (to==NULL || ...) S
> + if (unlikely(to==NULL) || ...) S
> * memcpy(to, from, size);
>
> @script:python depends on org@
> p << r.p;
> @@
>
> -coccilib.org.print_todo(p[0], "WARNING opportunity for kmemdep")
> +coccilib.org.print_todo(p[0], "WARNING opportunity for kmemdup")
>
> @script:python depends on report@
> p << r.p;
> @@
>
> -coccilib.report.print_report(p[0], "WARNING opportunity for kmemdep")
> +coccilib.report.print_report(p[0], "WARNING opportunity for kmemdup")
> --
> 1.9.1
>
> _______________________________________________
> Cocci mailing list
> Cocci@...teme.lip6.fr
> https://systeme.lip6.fr/mailman/listinfo/cocci
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