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From: Nathan Chancellor <nathan@kernel.org>
To: Hans de Goede <hdegoede@redhat.com>
Cc: kernel test robot <lkp@intel.com>,
	Mario Limonciello <mario.limonciello@dell.com>,
	kbuild-all@lists.01.org, clang-built-linux@googlegroups.com,
	Linux Memory Management List <linux-mm@kvack.org>
Subject: Re: [linux-next:master 7714/11865] drivers/platform/x86/dell/dell-smbios-smm.c:27:35: warning: unused variable 'dell_device_table'
Date: Thu, 4 Mar 2021 13:05:26 -0700	[thread overview]
Message-ID: <20210304200526.io7weii5xk2tlh4g@archlinux-ax161> (raw)
In-Reply-To: <1b24561f-5d9d-dcfb-a231-11be10722074@redhat.com>

On Thu, Mar 04, 2021 at 12:59:08PM +0100, Hans de Goede wrote:
> Hi,
> 
> On 2/20/21 4:16 PM, kernel test robot wrote:
> > Hi Mario,
> > 
> > First bad commit (maybe != root cause):
> > 
> > tree:   https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
> > head:   abaf6f60176f1ae9d946d63e4db63164600b7b1a
> > commit: f1e1ea516721d1ea0b21327ff9e6cb2c2bb86e28 [7714/11865] platform/x86: Move all dell drivers to their own subdirectory
> > config: x86_64-randconfig-r014-20210220 (attached as .config)
> > compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project c9439ca36342fb6013187d0a69aef92736951476)
> > reproduce (this is a W=1 build):
> >         wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
> >         chmod +x ~/bin/make.cross
> >         # install x86_64 cross compiling tool for clang build
> >         # apt-get install binutils-x86-64-linux-gnu
> >         # https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?id=f1e1ea516721d1ea0b21327ff9e6cb2c2bb86e28
> >         git remote add linux-next https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git
> >         git fetch --no-tags linux-next master
> >         git checkout f1e1ea516721d1ea0b21327ff9e6cb2c2bb86e28
> >         # save the attached .config to linux build tree
> >         COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=x86_64 
> > 
> > If you fix the issue, kindly add following tag as appropriate
> > Reported-by: kernel test robot <lkp@intel.com>
> > 
> > All warnings (new ones prefixed by >>):
> > 
> >>> drivers/platform/x86/dell/dell-smbios-smm.c:27:35: warning: unused variable 'dell_device_table' [-Wunused-const-variable]
> >    static const struct dmi_system_id dell_device_table[] __initconst = {
> >                                      ^
> >    1 warning generated.
> 
> So this table is only there so that it can be passed to the MODULE_DEVICE_TABLE() macro for auto-loading the module.
> 
> I guess that that macro used to give enough of a reference to the table for the compiler to not complain but that
> seems to have changed.

This particular config has CONFIG_DELL_SMBIOS_SMM=y, which means that
MODULE_DEVICE_TABLE() expands to nothing so it is indeed unused. I do
not think that anything changed on the compiler side as this is
reproducible with both GCC and clang. Do note that W=1 is needed to
reproduce this.

> I suggest that we just add an __maybe_unused to the declaration of the table to silence the warning.

Yes, this would probably be the best fix.

Cheers,
Nathan

> Regards,
> 
> Hans
> 
> 
> 
> 
> 
> > 
> > 
> > vim +/dell_device_table +27 drivers/platform/x86/dell/dell-smbios-smm.c
> > 
> > 549b4930f05765 drivers/platform/x86/dell-smbios-smm.c Mario Limonciello 2017-11-01  26  
> > 549b4930f05765 drivers/platform/x86/dell-smbios-smm.c Mario Limonciello 2017-11-01 @27  static const struct dmi_system_id dell_device_table[] __initconst = {
> > 549b4930f05765 drivers/platform/x86/dell-smbios-smm.c Mario Limonciello 2017-11-01  28  	{
> > 549b4930f05765 drivers/platform/x86/dell-smbios-smm.c Mario Limonciello 2017-11-01  29  		.ident = "Dell laptop",
> > 549b4930f05765 drivers/platform/x86/dell-smbios-smm.c Mario Limonciello 2017-11-01  30  		.matches = {
> > 549b4930f05765 drivers/platform/x86/dell-smbios-smm.c Mario Limonciello 2017-11-01  31  			DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
> > 549b4930f05765 drivers/platform/x86/dell-smbios-smm.c Mario Limonciello 2017-11-01  32  			DMI_MATCH(DMI_CHASSIS_TYPE, "8"),
> > 549b4930f05765 drivers/platform/x86/dell-smbios-smm.c Mario Limonciello 2017-11-01  33  		},
> > 549b4930f05765 drivers/platform/x86/dell-smbios-smm.c Mario Limonciello 2017-11-01  34  	},
> > 549b4930f05765 drivers/platform/x86/dell-smbios-smm.c Mario Limonciello 2017-11-01  35  	{
> > 549b4930f05765 drivers/platform/x86/dell-smbios-smm.c Mario Limonciello 2017-11-01  36  		.matches = {
> > 549b4930f05765 drivers/platform/x86/dell-smbios-smm.c Mario Limonciello 2017-11-01  37  			DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
> > 549b4930f05765 drivers/platform/x86/dell-smbios-smm.c Mario Limonciello 2017-11-01  38  			DMI_MATCH(DMI_CHASSIS_TYPE, "9"), /*Laptop*/
> > 549b4930f05765 drivers/platform/x86/dell-smbios-smm.c Mario Limonciello 2017-11-01  39  		},
> > 549b4930f05765 drivers/platform/x86/dell-smbios-smm.c Mario Limonciello 2017-11-01  40  	},
> > 549b4930f05765 drivers/platform/x86/dell-smbios-smm.c Mario Limonciello 2017-11-01  41  	{
> > 549b4930f05765 drivers/platform/x86/dell-smbios-smm.c Mario Limonciello 2017-11-01  42  		.matches = {
> > 549b4930f05765 drivers/platform/x86/dell-smbios-smm.c Mario Limonciello 2017-11-01  43  			DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
> > 549b4930f05765 drivers/platform/x86/dell-smbios-smm.c Mario Limonciello 2017-11-01  44  			DMI_MATCH(DMI_CHASSIS_TYPE, "10"), /*Notebook*/
> > 549b4930f05765 drivers/platform/x86/dell-smbios-smm.c Mario Limonciello 2017-11-01  45  		},
> > 549b4930f05765 drivers/platform/x86/dell-smbios-smm.c Mario Limonciello 2017-11-01  46  	},
> > 549b4930f05765 drivers/platform/x86/dell-smbios-smm.c Mario Limonciello 2017-11-01  47  	{
> > 549b4930f05765 drivers/platform/x86/dell-smbios-smm.c Mario Limonciello 2017-11-01  48  		.ident = "Dell Computer Corporation",
> > 549b4930f05765 drivers/platform/x86/dell-smbios-smm.c Mario Limonciello 2017-11-01  49  		.matches = {
> > 549b4930f05765 drivers/platform/x86/dell-smbios-smm.c Mario Limonciello 2017-11-01  50  			DMI_MATCH(DMI_SYS_VENDOR, "Dell Computer Corporation"),
> > 549b4930f05765 drivers/platform/x86/dell-smbios-smm.c Mario Limonciello 2017-11-01  51  			DMI_MATCH(DMI_CHASSIS_TYPE, "8"),
> > 549b4930f05765 drivers/platform/x86/dell-smbios-smm.c Mario Limonciello 2017-11-01  52  		},
> > 549b4930f05765 drivers/platform/x86/dell-smbios-smm.c Mario Limonciello 2017-11-01  53  	},
> > 549b4930f05765 drivers/platform/x86/dell-smbios-smm.c Mario Limonciello 2017-11-01  54  	{ }
> > 549b4930f05765 drivers/platform/x86/dell-smbios-smm.c Mario Limonciello 2017-11-01  55  };
> > 549b4930f05765 drivers/platform/x86/dell-smbios-smm.c Mario Limonciello 2017-11-01  56  MODULE_DEVICE_TABLE(dmi, dell_device_table);
> > 549b4930f05765 drivers/platform/x86/dell-smbios-smm.c Mario Limonciello 2017-11-01  57  
> > 
> > :::::: The code at line 27 was first introduced by commit
> > :::::: 549b4930f057658dc50d8010e66219233119a4d8 platform/x86: dell-smbios: Introduce dispatcher for SMM calls
> > 
> > :::::: TO: Mario Limonciello <mario.limonciello@dell.com>
> > :::::: CC: Darren Hart (VMware) <dvhart@infradead.org>
> > 
> > ---
> > 0-DAY CI Kernel Test Service, Intel Corporation
> > https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
> > 
> 
> 


WARNING: multiple messages have this Message-ID (diff)
From: Nathan Chancellor <nathan@kernel.org>
To: kbuild-all@lists.01.org
Subject: Re: [linux-next:master 7714/11865] drivers/platform/x86/dell/dell-smbios-smm.c:27:35: warning: unused variable 'dell_device_table'
Date: Thu, 04 Mar 2021 13:05:26 -0700	[thread overview]
Message-ID: <20210304200526.io7weii5xk2tlh4g@archlinux-ax161> (raw)
In-Reply-To: <1b24561f-5d9d-dcfb-a231-11be10722074@redhat.com>

[-- Attachment #1: Type: text/plain, Size: 6903 bytes --]

On Thu, Mar 04, 2021 at 12:59:08PM +0100, Hans de Goede wrote:
> Hi,
> 
> On 2/20/21 4:16 PM, kernel test robot wrote:
> > Hi Mario,
> > 
> > First bad commit (maybe != root cause):
> > 
> > tree:   https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
> > head:   abaf6f60176f1ae9d946d63e4db63164600b7b1a
> > commit: f1e1ea516721d1ea0b21327ff9e6cb2c2bb86e28 [7714/11865] platform/x86: Move all dell drivers to their own subdirectory
> > config: x86_64-randconfig-r014-20210220 (attached as .config)
> > compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project c9439ca36342fb6013187d0a69aef92736951476)
> > reproduce (this is a W=1 build):
> >         wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
> >         chmod +x ~/bin/make.cross
> >         # install x86_64 cross compiling tool for clang build
> >         # apt-get install binutils-x86-64-linux-gnu
> >         # https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?id=f1e1ea516721d1ea0b21327ff9e6cb2c2bb86e28
> >         git remote add linux-next https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git
> >         git fetch --no-tags linux-next master
> >         git checkout f1e1ea516721d1ea0b21327ff9e6cb2c2bb86e28
> >         # save the attached .config to linux build tree
> >         COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=x86_64 
> > 
> > If you fix the issue, kindly add following tag as appropriate
> > Reported-by: kernel test robot <lkp@intel.com>
> > 
> > All warnings (new ones prefixed by >>):
> > 
> >>> drivers/platform/x86/dell/dell-smbios-smm.c:27:35: warning: unused variable 'dell_device_table' [-Wunused-const-variable]
> >    static const struct dmi_system_id dell_device_table[] __initconst = {
> >                                      ^
> >    1 warning generated.
> 
> So this table is only there so that it can be passed to the MODULE_DEVICE_TABLE() macro for auto-loading the module.
> 
> I guess that that macro used to give enough of a reference to the table for the compiler to not complain but that
> seems to have changed.

This particular config has CONFIG_DELL_SMBIOS_SMM=y, which means that
MODULE_DEVICE_TABLE() expands to nothing so it is indeed unused. I do
not think that anything changed on the compiler side as this is
reproducible with both GCC and clang. Do note that W=1 is needed to
reproduce this.

> I suggest that we just add an __maybe_unused to the declaration of the table to silence the warning.

Yes, this would probably be the best fix.

Cheers,
Nathan

> Regards,
> 
> Hans
> 
> 
> 
> 
> 
> > 
> > 
> > vim +/dell_device_table +27 drivers/platform/x86/dell/dell-smbios-smm.c
> > 
> > 549b4930f05765 drivers/platform/x86/dell-smbios-smm.c Mario Limonciello 2017-11-01  26  
> > 549b4930f05765 drivers/platform/x86/dell-smbios-smm.c Mario Limonciello 2017-11-01 @27  static const struct dmi_system_id dell_device_table[] __initconst = {
> > 549b4930f05765 drivers/platform/x86/dell-smbios-smm.c Mario Limonciello 2017-11-01  28  	{
> > 549b4930f05765 drivers/platform/x86/dell-smbios-smm.c Mario Limonciello 2017-11-01  29  		.ident = "Dell laptop",
> > 549b4930f05765 drivers/platform/x86/dell-smbios-smm.c Mario Limonciello 2017-11-01  30  		.matches = {
> > 549b4930f05765 drivers/platform/x86/dell-smbios-smm.c Mario Limonciello 2017-11-01  31  			DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
> > 549b4930f05765 drivers/platform/x86/dell-smbios-smm.c Mario Limonciello 2017-11-01  32  			DMI_MATCH(DMI_CHASSIS_TYPE, "8"),
> > 549b4930f05765 drivers/platform/x86/dell-smbios-smm.c Mario Limonciello 2017-11-01  33  		},
> > 549b4930f05765 drivers/platform/x86/dell-smbios-smm.c Mario Limonciello 2017-11-01  34  	},
> > 549b4930f05765 drivers/platform/x86/dell-smbios-smm.c Mario Limonciello 2017-11-01  35  	{
> > 549b4930f05765 drivers/platform/x86/dell-smbios-smm.c Mario Limonciello 2017-11-01  36  		.matches = {
> > 549b4930f05765 drivers/platform/x86/dell-smbios-smm.c Mario Limonciello 2017-11-01  37  			DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
> > 549b4930f05765 drivers/platform/x86/dell-smbios-smm.c Mario Limonciello 2017-11-01  38  			DMI_MATCH(DMI_CHASSIS_TYPE, "9"), /*Laptop*/
> > 549b4930f05765 drivers/platform/x86/dell-smbios-smm.c Mario Limonciello 2017-11-01  39  		},
> > 549b4930f05765 drivers/platform/x86/dell-smbios-smm.c Mario Limonciello 2017-11-01  40  	},
> > 549b4930f05765 drivers/platform/x86/dell-smbios-smm.c Mario Limonciello 2017-11-01  41  	{
> > 549b4930f05765 drivers/platform/x86/dell-smbios-smm.c Mario Limonciello 2017-11-01  42  		.matches = {
> > 549b4930f05765 drivers/platform/x86/dell-smbios-smm.c Mario Limonciello 2017-11-01  43  			DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
> > 549b4930f05765 drivers/platform/x86/dell-smbios-smm.c Mario Limonciello 2017-11-01  44  			DMI_MATCH(DMI_CHASSIS_TYPE, "10"), /*Notebook*/
> > 549b4930f05765 drivers/platform/x86/dell-smbios-smm.c Mario Limonciello 2017-11-01  45  		},
> > 549b4930f05765 drivers/platform/x86/dell-smbios-smm.c Mario Limonciello 2017-11-01  46  	},
> > 549b4930f05765 drivers/platform/x86/dell-smbios-smm.c Mario Limonciello 2017-11-01  47  	{
> > 549b4930f05765 drivers/platform/x86/dell-smbios-smm.c Mario Limonciello 2017-11-01  48  		.ident = "Dell Computer Corporation",
> > 549b4930f05765 drivers/platform/x86/dell-smbios-smm.c Mario Limonciello 2017-11-01  49  		.matches = {
> > 549b4930f05765 drivers/platform/x86/dell-smbios-smm.c Mario Limonciello 2017-11-01  50  			DMI_MATCH(DMI_SYS_VENDOR, "Dell Computer Corporation"),
> > 549b4930f05765 drivers/platform/x86/dell-smbios-smm.c Mario Limonciello 2017-11-01  51  			DMI_MATCH(DMI_CHASSIS_TYPE, "8"),
> > 549b4930f05765 drivers/platform/x86/dell-smbios-smm.c Mario Limonciello 2017-11-01  52  		},
> > 549b4930f05765 drivers/platform/x86/dell-smbios-smm.c Mario Limonciello 2017-11-01  53  	},
> > 549b4930f05765 drivers/platform/x86/dell-smbios-smm.c Mario Limonciello 2017-11-01  54  	{ }
> > 549b4930f05765 drivers/platform/x86/dell-smbios-smm.c Mario Limonciello 2017-11-01  55  };
> > 549b4930f05765 drivers/platform/x86/dell-smbios-smm.c Mario Limonciello 2017-11-01  56  MODULE_DEVICE_TABLE(dmi, dell_device_table);
> > 549b4930f05765 drivers/platform/x86/dell-smbios-smm.c Mario Limonciello 2017-11-01  57  
> > 
> > :::::: The code at line 27 was first introduced by commit
> > :::::: 549b4930f057658dc50d8010e66219233119a4d8 platform/x86: dell-smbios: Introduce dispatcher for SMM calls
> > 
> > :::::: TO: Mario Limonciello <mario.limonciello@dell.com>
> > :::::: CC: Darren Hart (VMware) <dvhart@infradead.org>
> > 
> > ---
> > 0-DAY CI Kernel Test Service, Intel Corporation
> > https://lists.01.org/hyperkitty/list/kbuild-all(a)lists.01.org
> > 
> 
> 

  reply	other threads:[~2021-03-04 20:05 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-20 15:16 [linux-next:master 7714/11865] drivers/platform/x86/dell/dell-smbios-smm.c:27:35: warning: unused variable 'dell_device_table' kernel test robot
2021-02-20 15:16 ` kernel test robot
2021-03-04 11:59 ` Hans de Goede
2021-03-04 11:59   ` Hans de Goede
2021-03-04 20:05   ` Nathan Chancellor [this message]
2021-03-04 20:05     ` Nathan Chancellor

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