From: Shaun Ruffell <sruffell@sruffell.net>
To: Matthias Maennich <maennich@google.com>
Cc: linux-kernel@vger.kernel.org, Martijn Coenen <maco@android.com>,
Joel Fernandes <joel@joelfernandes.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Jessica Yu <jeyu@kernel.org>,
Masahiro Yamada <yamada.masahiro@socionext.com>
Subject: Re: [PATCH] modpost: Copy namespace string into 'struct symbol'
Date: Tue, 1 Oct 2019 14:37:04 -0500 [thread overview]
Message-ID: <20191001193704.txidwxf3h4te4rtr@sruffell.net> (raw)
In-Reply-To: <20191001161923.GH90796@google.com>
On Tue, Oct 01, 2019 at 05:19:23PM +0100, Matthias Maennich wrote:
> On Mon, Sep 30, 2019 at 04:20:46PM -0500, Shaun Ruffell wrote:
> > On Fri, Sep 27, 2019 at 09:03:46AM +0100, Matthias Maennich wrote:
> > > On Thu, Sep 26, 2019 at 05:24:46PM -0500, Shaun Ruffell wrote:
> > > > When building an out-of-tree module I was receiving many warnings from
> > > > modpost like:
> > > >
> > > > WARNING: module dahdi_vpmadt032_loader uses symbol __kmalloc from namespace ts/dahdi-linux/drivers/dahdi/dahdi-version.o: ..., but does not import it.
> > > > WARNING: module dahdi_vpmadt032_loader uses symbol vpmadtreg_register from namespace linux/drivers/dahdi/dahdi-version.o: ..., but does not import it.
> > > > WARNING: module dahdi_vpmadt032_loader uses symbol param_ops_int from namespace ahdi-linux/drivers/dahdi/dahdi-version.o: ..., but does not import it.
> > > > WARNING: module dahdi_vpmadt032_loader uses symbol __init_waitqueue_head from namespace ux/drivers/dahdi/dahdi-version.o: ..., but does not import it.
> > > > ...
> > > >
> > > > The fundamental issue appears to be that read_dump() is passing a
> > > > pointer to a statically allocated buffer for the namespace which is
> > > > reused as the file is parsed.
> > >
> > > Hi Shaun,
> > >
> > > Thanks for working on this. I think you are right about the root cause
> > > of this. I will have a closer look at your fix later today.
> >
> > Thanks Matthias.
>
> In the meantime, Masahiro came up with an alternative approach to
> address this problem:
> https://lore.kernel.org/lkml/20190927093603.9140-2-yamada.masahiro@socionext.com/
> How do you think about it? It ignores the memory allocation problem that
> you addressed as modpost is a host tool after all. As part of the patch
> series, an alternative format for the namespace ksymtab entry is
> suggested that also changes the way modpost has to deal with it.
Masahiro's patch set looks good to me.
My only comment would be that I felt it preferable for
sym_add_exported() to treat the two string arguments passed to it the
same way. I feel the way it is currently violates the princple of least
surprise. However I accept this is just my personal opinion.
> > > > @@ -672,7 +696,6 @@ static void handle_modversions(struct module *mod, struct elf_info *info,
> > > > unsigned int crc;
> > > > enum export export;
> > > > bool is_crc = false;
> > > > - const char *name, *namespace;
> > > >
> > > > if ((!is_vmlinux(mod->name) || mod->is_dot_o) &&
> > > > strstarts(symname, "__ksymtab"))
> > > > @@ -744,9 +767,13 @@ static void handle_modversions(struct module *mod, struct elf_info *info,
> > > > default:
> > > > /* All exported symbols */
> > > > if (strstarts(symname, "__ksymtab_")) {
> > > > + const char *name, *namespace;
> > > > +
> > > > name = symname + strlen("__ksymtab_");
> > > > namespace = sym_extract_namespace(&name);
> > > > sym_add_exported(name, namespace, mod, export);
> > > > + if (namespace)
> > > > + free((char *)name);
> > >
> > > This probably should free namespace instead.
> >
> > Given the implementation of sym_extract_namespace below, I believe
> > free((char *)name) is correct.
>
> Yeah, you are right. I was just noticing the inconsistency and thought
> it was obviously wrong. So, I was wrong. Sorry and thanks for the
> explanation.
>
> >
> > static const char *sym_extract_namespace(const char **symname)
> > {
> > size_t n;
> > char *dupsymname;
> >
> > n = strcspn(*symname, ".");
> > if (n < strlen(*symname) - 1) {
> > dupsymname = NOFAIL(strdup(*symname));
> > dupsymname[n] = '\0';
> > *symname = dupsymname;
> > return dupsymname + n + 1;
> > }
> >
> > return NULL;
> > }
> >
> > I agree that freeing name instead of namespace is a little surprising
> > unless you know the implementation of sym_extract_namespace.
> >
> > I thought about changing the the signature of sym_extract_namespace() to
> > make it clear when the symname is used to return a new allocation or
> > not, and given your comment, perhaps I should have.
>
> I would rather follow-up with Masahiro's approach for now. What do you
> think?
I agree that following-up with Masahiro's patch set is the better
option.
Cheers,
Shaun
next prev parent reply other threads:[~2019-10-01 19:37 UTC|newest]
Thread overview: 134+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-16 12:21 [PATCH 0/6] Symbol namespaces Martijn Coenen
2018-07-16 12:21 ` [PATCH 1/6] export: explicitly align struct kernel_symbol Martijn Coenen
2018-07-16 12:21 ` [PATCH 2/6] module: add support for symbol namespaces Martijn Coenen
2018-07-19 16:32 ` Jessica Yu
2018-07-20 7:54 ` Martijn Coenen
2018-07-20 14:49 ` Jessica Yu
2018-07-20 15:42 ` Martijn Coenen
2018-07-23 11:12 ` Jessica Yu
2018-07-24 7:44 ` Martijn Coenen
2018-07-24 7:56 ` Martijn Coenen
2018-07-25 15:55 ` Jessica Yu
2018-07-25 16:48 ` Lucas De Marchi
2018-07-26 7:44 ` Martijn Coenen
2018-07-16 12:21 ` [PATCH 3/6] modpost: add support for checking " Martijn Coenen
2018-07-16 12:21 ` [PATCH 4/6] modpost: add support for generating namespace dependencies Martijn Coenen
2018-07-23 6:49 ` Jessica Yu
2018-07-16 12:21 ` [PATCH 5/6] scripts: Coccinelle script for " Martijn Coenen
2018-07-16 12:21 ` [PATCH 6/6] RFC: USB: storage: move symbols into USB_STORAGE namespace Martijn Coenen
2018-07-17 15:04 ` Alan Stern
2018-07-18 13:28 ` Martijn Coenen
2018-07-16 15:33 ` [PATCH 0/6] Symbol namespaces Greg Kroah-Hartman
2018-07-23 14:28 ` Arnd Bergmann
2018-07-24 8:09 ` Martijn Coenen
2018-07-24 9:08 ` Arnd Bergmann
2019-08-13 12:16 ` [PATCH v2 0/10] Symbol namespaces - RFC Matthias Maennich
2019-08-13 12:16 ` [PATCH v2 01/10] module: support reading multiple values per modinfo tag Matthias Maennich
2019-08-13 12:40 ` Greg KH
2019-08-13 12:16 ` [PATCH v2 02/10] export: explicitly align struct kernel_symbol Matthias Maennich
2019-08-13 12:41 ` Greg KH
2019-08-13 12:17 ` [PATCH v2 03/10] module: add support for symbol namespaces Matthias Maennich
2019-08-13 15:26 ` Greg KH
2019-08-13 12:17 ` [PATCH v2 04/10] modpost: " Matthias Maennich
2019-08-13 15:27 ` Greg KH
2019-08-13 12:17 ` [PATCH v2 05/10] module: add config option MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS Matthias Maennich
2019-08-13 18:17 ` Greg KH
2019-08-13 20:15 ` Saravana Kannan
2019-08-14 12:54 ` Matthias Maennich
2019-08-14 17:34 ` Saravana Kannan
2019-08-13 12:17 ` [PATCH v2 06/10] export: allow definition default namespaces in Makefiles or sources Matthias Maennich
2019-08-13 18:16 ` Greg KH
2019-08-13 18:16 ` Greg KH
2019-08-13 12:17 ` [PATCH v2 07/10] modpost: add support for generating namespace dependencies Matthias Maennich
2019-08-13 18:21 ` Greg KH
2019-08-13 12:17 ` [PATCH v2 08/10] scripts: Coccinelle script for " Matthias Maennich
2019-08-13 12:31 ` Julia Lawall
2019-08-13 12:44 ` Greg KH
2019-08-14 6:36 ` [Cocci] " Himanshu Jha
2019-08-14 8:03 ` Matthias Maennich
2019-08-15 13:50 ` [v2 " Markus Elfring
2019-08-22 9:18 ` Matthias Maennich
2019-08-22 11:00 ` Markus Elfring
2019-08-13 12:17 ` [PATCH v2 09/10] usb-storage: remove single-use define for debugging Matthias Maennich
2019-08-13 12:42 ` Greg KH
2019-08-13 13:12 ` Greg KH
2019-08-13 12:17 ` [PATCH v2 10/10] RFC: usb-storage: export symbols in USB_STORAGE namespace Matthias Maennich
2019-08-13 12:45 ` Greg KH
2019-08-13 12:47 ` Greg KH
2019-08-13 15:02 ` Matthias Maennich
[not found] ` <20190821114955.12788-1-maennich@google.com>
2019-08-21 11:49 ` [PATCH v3 01/11] module: support reading multiple values per modinfo tag Matthias Maennich
2019-08-21 11:49 ` [PATCH v3 02/11] export: explicitly align struct kernel_symbol Matthias Maennich
2019-08-21 11:49 ` [PATCH v3 03/11] module: add support for symbol namespaces Matthias Maennich
2019-08-27 15:37 ` Jessica Yu
2019-08-27 16:04 ` Matthias Maennich
2019-08-21 11:49 ` [PATCH v3 04/11] modpost: " Matthias Maennich
2019-08-26 16:21 ` Jessica Yu
2019-08-27 14:41 ` Matthias Maennich
2019-08-28 9:43 ` Jessica Yu
2019-08-28 9:55 ` Matthias Maennich
2019-08-28 10:16 ` Jessica Yu
2019-08-21 11:49 ` [PATCH v3 05/11] module: add config option MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS Matthias Maennich
2019-08-21 11:49 ` [PATCH v3 06/11] export: allow definition default namespaces in Makefiles or sources Matthias Maennich
2019-08-28 10:49 ` Jessica Yu
2019-08-28 10:56 ` Matthias Maennich
2019-08-21 11:49 ` [PATCH v3 07/11] modpost: add support for generating namespace dependencies Matthias Maennich
2019-08-21 11:49 ` [PATCH v3 08/11] scripts: Coccinelle script for " Matthias Maennich
2019-08-22 6:09 ` [v3 " Markus Elfring
2019-08-29 12:13 ` [PATCH v3 " Jessica Yu
2019-08-21 11:49 ` [PATCH v3 09/11] usb-storage: remove single-use define for debugging Matthias Maennich
2019-08-21 12:37 ` Greg KH
2019-08-21 13:21 ` Thomas Gleixner
2019-08-21 13:32 ` Greg KH
2019-08-21 11:49 ` [PATCH v3 10/11] RFC: usb-storage: export symbols in USB_STORAGE namespace Matthias Maennich
2019-08-21 12:38 ` Greg KH
2019-08-21 14:36 ` Jessica Yu
2019-08-21 23:13 ` Christoph Hellwig
2019-08-22 8:32 ` Matthias Maennich
2019-09-03 15:06 ` [PATCH v4 00/12] Symbol Namespaces Matthias Maennich
2019-09-03 15:06 ` [PATCH v4 01/12] module: support reading multiple values per modinfo tag Matthias Maennich
2019-09-03 15:06 ` [PATCH v4 02/12] export: explicitly align struct kernel_symbol Matthias Maennich
2019-09-03 15:06 ` [PATCH v4 03/12] module: add support for symbol namespaces Matthias Maennich
2019-09-03 15:06 ` [PATCH v4 04/12] modpost: " Matthias Maennich
2019-09-03 15:06 ` [PATCH v4 05/12] module: add config option MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS Matthias Maennich
2019-09-03 15:06 ` [PATCH v4 06/12] export: allow definition default namespaces in Makefiles or sources Matthias Maennich
2019-09-03 15:06 ` [PATCH v4 07/12] modpost: add support for generating namespace dependencies Matthias Maennich
2019-09-03 15:06 ` [PATCH v4 08/12] scripts: Coccinelle script for " Matthias Maennich
2019-09-04 9:53 ` Masahiro Yamada
2019-09-05 14:46 ` Matthias Maennich
2019-09-03 15:06 ` [PATCH v4 09/12] docs: Add documentation for Symbol Namespaces Matthias Maennich
2019-09-04 7:16 ` Greg KH
2019-09-03 15:06 ` [PATCH v4 10/12] usb-storage: remove single-use define for debugging Matthias Maennich
2019-09-03 15:06 ` [PATCH v4 11/12] RFC: usb-storage: export symbols in USB_STORAGE namespace Matthias Maennich
2019-09-03 15:06 ` [PATCH v4 12/12] RFC: watchdog: export core symbols in WATCHDOG_CORE namespace Matthias Maennich
2019-09-03 16:10 ` Guenter Roeck
2019-09-04 8:45 ` Masahiro Yamada
2019-09-04 12:12 ` Guenter Roeck
2019-09-04 16:16 ` [usb-storage] " Matthew Dharm
2019-09-05 10:41 ` Jessica Yu
2019-09-05 10:52 ` Arnd Bergmann
2019-09-05 11:16 ` Jessica Yu
2019-09-05 11:25 ` Masahiro Yamada
2019-09-05 12:00 ` Greg Kroah-Hartman
2019-09-05 11:25 ` Matthias Maennich
2019-09-04 9:37 ` [PATCH v4 00/12] Symbol Namespaces Masahiro Yamada
2019-09-06 10:32 ` [PATCH v5 00/11] " Matthias Maennich
2019-09-06 10:32 ` [PATCH v5 01/11] module: support reading multiple values per modinfo tag Matthias Maennich
2019-09-06 10:32 ` [PATCH v5 02/11] export: explicitly align struct kernel_symbol Matthias Maennich
2019-09-06 10:32 ` [PATCH v5 03/11] module: add support for symbol namespaces Matthias Maennich
2019-09-06 10:32 ` [PATCH v5 04/11] modpost: " Matthias Maennich
2019-09-26 22:24 ` [PATCH] modpost: Copy namespace string into 'struct symbol' Shaun Ruffell
2019-09-27 5:31 ` Greg Kroah-Hartman
2019-09-27 8:03 ` Matthias Maennich
2019-09-30 21:20 ` Shaun Ruffell
2019-10-01 16:19 ` Matthias Maennich
2019-10-01 19:37 ` Shaun Ruffell [this message]
2019-09-06 10:32 ` [PATCH v5 05/11] module: add config option MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS Matthias Maennich
2019-09-06 10:32 ` [PATCH v5 06/11] export: allow definition default namespaces in Makefiles or sources Matthias Maennich
2019-09-06 10:32 ` [PATCH v5 07/11] modpost: add support for generating namespace dependencies Matthias Maennich
2019-09-06 10:32 ` [PATCH v5 08/11] scripts: Coccinelle script for " Matthias Maennich
2019-09-06 10:32 ` [PATCH v5 09/11] docs: Add documentation for Symbol Namespaces Matthias Maennich
2019-09-06 10:32 ` [PATCH v5 10/11] usb-storage: remove single-use define for debugging Matthias Maennich
2019-09-06 12:59 ` Jessica Yu
2019-09-06 13:22 ` Greg KH
2019-09-06 10:32 ` [PATCH v5 11/11] usb-storage: export symbols in USB_STORAGE namespace Matthias Maennich
2019-09-09 8:35 ` [PATCH v5 00/11] Symbol Namespaces Jessica Yu
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