linux-kernel - Re: [PATCH -next] drivers/base/power: fix build error without SYSFS

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Date:   Tue, 3 Mar 2020 10:26:54 +0800
From:   Hongbo Yao <yaohongbo@...wei.com>
To:     Greg KH <gregkh@...uxfoundation.org>
CC:     <christian.brauner@...ntu.com>, <linux-kernel@...r.kernel.org>,
        <linux-pm@...r.kernel.org>, <chenzhou10@...wei.com>,
        <rjw@...ysocki.net>, <pavel@....cz>
Subject: Re: [PATCH -next] drivers/base/power: fix build error without SYSFS



On 2020/3/2 17:23, Greg KH wrote:
> On Mon, Mar 02, 2020 at 05:29:18PM +0800, Hongbo Yao wrote:
>> If CONFIG_SYSFS=n, the following error is seen while building 
>> drivers/base/power/sysfs.c:
>>
>> drivers/base/power/sysfs.c: In function dpm_sysfs_change_owner:
>> drivers/base/power/sysfs.c:708:44: error: passing argument 2 of
>> sysfs_group_change_owner from incompatible pointer type
>> [-Werror=incompatible-pointer-types]
>>   rc = sysfs_group_change_owner(&dev->kobj, &pm_attr_group, kuid, kgid);
>>                                             ^
>> In file included from ./include/linux/kobject.h:20:0,
>>                  from ./include/linux/device.h:17,
>>                  from drivers/base/power/sysfs.c:3:
>> ./include/linux/sysfs.h:564:19: note: expected const struct
>> attribute_group ** but argument is of type const struct attribute_group *
>>
>> dpm_sysfs_change_owner() should only used when CONFIG_SYSFS is
>> defined.
>>
>> Reported-by: Hulk Robot <hulkci@...wei.com>
>> Fixes: 3b52fc5d7876 ("drivers/base/power: add dpm_sysfs_change_owner()")
>> Signed-off-by: Hongbo Yao <yaohongbo@...wei.com>
>> ---
>>  drivers/base/power/power.h | 10 +++++++++-
>>  drivers/base/power/sysfs.c |  2 ++
> 
> You shouldn't have to add #ifdefs to a .c file here, it should all be
> able to be fixed in the .h file by putting proper "empty" functions.

  I think it's a little difficult to fix this without changing the .c file,
  unless changing the Kconfig.

  This function was implemeted when CONFIG_PM=y, and if CONFIG_PM=n, this
  function would be "empty".

  However, I found this function should depends on CONFIG_SYSFS, if
  CONFIG_SYSFS=n, this function should also be empty, so only changing the
  dependency of the header file will cause redefinition.

  thanks,
  Hongbo.

> thanks,
> 
> greg k-h
> 
> .
>