From: Julia Lawall <julia.lawall@inria.fr>
To: Denis Efremov <efremov@linux.com>
Cc: cocci@systeme.lip6.fr, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v6] coccinelle: api: add kvfree script
Date: Mon, 3 Aug 2020 14:18:03 +0200 (CEST) [thread overview]
Message-ID: <alpine.DEB.2.22.394.2008031416301.27678@hadrien> (raw)
In-Reply-To: <a8d8eade-1d98-b8d9-7c66-bd05b22af751@linux.com>
On Mon, 3 Aug 2020, Denis Efremov wrote:
>
>
> On 8/2/20 11:24 PM, Julia Lawall wrote:
> >> +@initialize:python@
> >> +@@
> >> +# low-level memory api
> >> +filter = frozenset(['__vmalloc_area_node'])
> >> +
> >> +def relevant(p):
> >> + return not (filter & {el.current_element for el in p})
> >
> > Is this used?
>
> I'll remove it in v8. Or do you want me to add iterate_dir_item() in the list?
What is that?
>
> >
> > Otherwise, I think it would be good to not warn about a use of kvfree
> > if that use is reachable from a kvmalloc. There seems to be such a false
> > positive in fs/btrfs/send.c, on line 1118.
>
> I don't know how to handle this case without position filter.
> It's too complex. In iterate_dir_item() there is:
> buf = kmalloc(buf_len, GFP_KERNEL);
> while(...) {
> if (...) {
> if (is_vmalloc_addr(buf)) {
> vfree(buf);
> ...
> } else {
> char *tmp = krealloc(buf, ...);
>
> if (!tmp)
> kfree(buf);
> ...
> }
> if (!buf) {
> buf = kvmalloc(buf_len, GFP_KERNEL);
> ...
> }
> }
> }
> kvfree(buf);
>
> Adding "when != kvfree(E)" is not enough:
> * E = \(kvmalloc\|kvzalloc\|kvcalloc\|kvzalloc_node\|kvmalloc_node\|
> * kvmalloc_array\)(...)@k
> ... when != is_vmalloc_addr(E)
> + when != kvfree(E)
> when any
> * \(kfree\|kzfree\|vfree\|vfree_atomic\)(E)@p
Why not just
@ok exists@
position p;
expression E;
@@
E = kvalloc(...)
...
kvfree@p(...)
Probably that is what you mean by a position filter, but why not add a
position filter?
julia
> >
> > It also seems that when there are both a kmalloc and a vmalloc, there is
> > no warning if kfree or vfree is used. Is that intentional?
> >
>
> No, I will try to address it in v8.
>
> Regards,
> Denis
>
next prev parent reply other threads:[~2020-08-03 12:18 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-05 20:42 [PATCH] coccinelle: api: add kvfree script Denis Efremov
2020-06-05 20:51 ` [Cocci] " Julia Lawall
2020-06-05 21:15 ` Denis Efremov
2020-06-05 21:19 ` Julia Lawall
2020-06-14 9:03 ` Denis Efremov
2020-06-14 9:17 ` Julia Lawall
2020-06-14 9:24 ` Denis Efremov
2020-06-14 18:36 ` [PATCH v2] " Denis Efremov
2020-07-17 12:00 ` Denis Efremov
2020-07-30 14:01 ` [PATCH v3] " Denis Efremov
2020-07-30 14:05 ` Denis Efremov
2020-07-30 14:07 ` [PATCH v4] " Denis Efremov
2020-07-30 20:15 ` Julia Lawall
2020-07-30 20:38 ` Julia Lawall
2020-07-31 8:31 ` Denis Efremov
2020-07-31 8:48 ` Julia Lawall
2020-07-31 10:47 ` [PATCH v5] " Denis Efremov
2020-07-31 21:00 ` [PATCH v6] " Denis Efremov
2020-08-02 20:24 ` Julia Lawall
2020-08-03 11:33 ` Denis Efremov
2020-08-03 12:18 ` Julia Lawall [this message]
2020-08-03 11:45 ` Denis Efremov
2020-08-03 12:12 ` Julia Lawall
2020-08-03 18:34 ` [PATCH v7] coccinelle: api: add kfree_mismatch script Denis Efremov
2020-09-21 17:15 ` Denis Efremov
2020-10-15 20:48 ` Julia Lawall
2020-10-16 8:54 ` [PATCH v8] " Denis Efremov
2020-10-17 21:17 ` [Cocci] " Julia Lawall
[not found] <3aea12cf-68dc-e140-936f-cfefb2adbc8f@web.de>
2020-08-02 7:09 ` [PATCH v6] coccinelle: api: add kvfree script Julia Lawall
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