netdev - Re: [PATCH net-next v3 2/3] net: fsl: Allow most drivers to be built with COMPILE

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Date:   Thu, 17 Nov 2016 09:38:23 +0800
From:   Fengguang Wu <lkp@...el.com>
To:     Florian Fainelli <f.fainelli@...il.com>
Cc:     kbuild-all@...org, netdev@...r.kernel.org, davem@...emloft.net,
        mw@...ihalf.com, arnd@...db.de, gregory.clement@...e-electrons.com,
        Shaohui.Xie@...escale.com
Subject: Re: [PATCH net-next v3 2/3] net: fsl: Allow most drivers to be built
 with COMPILE_TEST

On Wed, Nov 16, 2016 at 11:52:45AM -0800, Florian Fainelli wrote:
>On 11/15/2016 07:23 PM, kbuild test robot wrote:
>> Hi Florian,
>>
>> [auto build test WARNING on net-next/master]
>>
>> url:    https://github.com/0day-ci/linux/commits/Florian-Fainelli/net-gianfar_ptp-Rename-FS-bit-to-FIPERST/20161116-095805
>> config: sh-allmodconfig (attached as .config)
>> compiler: sh4-linux-gnu-gcc (Debian 6.1.1-9) 6.1.1 20160705
>> reproduce:
>>         wget https://git.kernel.org/cgit/linux/kernel/git/wfg/lkp-tests.git/plain/sbin/make.cross -O ~/bin/make.cross
>>         chmod +x ~/bin/make.cross
>>         # save the attached .config to linux build tree
>>         make.cross ARCH=sh
>>
>> All warnings (new ones prefixed by >>):
>>
>>    drivers/net/ethernet/freescale/fsl_pq_mdio.c: In function 'fsl_pq_mdio_remove':
>>>> drivers/net/ethernet/freescale/fsl_pq_mdio.c:498:27: warning: unused variable 'priv' [-Wunused-variable]
>>      struct fsl_pq_mdio_priv *priv = bus->priv;
>
>Humm, this looks bogus, the variable is used see below:
>
>>                               ^~~~
>>
>> vim +/priv +498 drivers/net/ethernet/freescale/fsl_pq_mdio.c
>>
>> 1577ecef drivers/net/fsl_pq_mdio.c                    Andy Fleming    2009-02-04  482  	return 0;
>> 1577ecef drivers/net/fsl_pq_mdio.c                    Andy Fleming    2009-02-04  483
>> dd3b8a32 drivers/net/ethernet/freescale/fsl_pq_mdio.c Timur Tabi      2012-08-29  484  error:
>> dd3b8a32 drivers/net/ethernet/freescale/fsl_pq_mdio.c Timur Tabi      2012-08-29  485  	if (priv->map)
>> b3319b10 drivers/net/fsl_pq_mdio.c                    Anton Vorontsov 2009-12-30  486  		iounmap(priv->map);
>> dd3b8a32 drivers/net/ethernet/freescale/fsl_pq_mdio.c Timur Tabi      2012-08-29  487
>> 1577ecef drivers/net/fsl_pq_mdio.c                    Andy Fleming    2009-02-04  488  	kfree(new_bus);
>> dd3b8a32 drivers/net/ethernet/freescale/fsl_pq_mdio.c Timur Tabi      2012-08-29  489
>> 1577ecef drivers/net/fsl_pq_mdio.c                    Andy Fleming    2009-02-04  490  	return err;
>> 1577ecef drivers/net/fsl_pq_mdio.c                    Andy Fleming    2009-02-04  491  }
>> 1577ecef drivers/net/fsl_pq_mdio.c                    Andy Fleming    2009-02-04  492
>> 1577ecef drivers/net/fsl_pq_mdio.c                    Andy Fleming    2009-02-04  493
>> 5078ac79 drivers/net/ethernet/freescale/fsl_pq_mdio.c Timur Tabi      2012-08-29  494  static int fsl_pq_mdio_remove(struct platform_device *pdev)
>> 1577ecef drivers/net/fsl_pq_mdio.c                    Andy Fleming    2009-02-04  495  {
>> 5078ac79 drivers/net/ethernet/freescale/fsl_pq_mdio.c Timur Tabi      2012-08-29  496  	struct device *device = &pdev->dev;
>> 1577ecef drivers/net/fsl_pq_mdio.c                    Andy Fleming    2009-02-04  497  	struct mii_bus *bus = dev_get_drvdata(device);
>> b3319b10 drivers/net/fsl_pq_mdio.c                    Anton Vorontsov 2009-12-30 @498  	struct fsl_pq_mdio_priv *priv = bus->priv;
>> 1577ecef drivers/net/fsl_pq_mdio.c                    Andy Fleming    2009-02-04  499
>> 1577ecef drivers/net/fsl_pq_mdio.c                    Andy Fleming    2009-02-04  500  	mdiobus_unregister(bus);
>> 1577ecef drivers/net/fsl_pq_mdio.c                    Andy Fleming    2009-02-04  501
>> b3319b10 drivers/net/fsl_pq_mdio.c                    Anton Vorontsov 2009-12-30  502  	iounmap(priv->map);
>
>Right here.
>
>What compiler version is this?

Compiler is sh4-linux-gnu-gcc (Debian 6.1.1-9) 6.1.1 20160705.

include/asm-generic/io.h conditionally defines iounmap() to be an
empty inline function, which may explain the warning on sh4.

General speaking, it's a false warning. The solution could be to teach
the robot to ignore such 'unused variable' warnings in non-x86 archs.

Thanks,
Fengguang