Re: [linux-next:master 4204/5575] arch/powerpc/kernel/interrupt.c:542:55: error: suggest braces around empty body in an 'if' statement

[Christophe Leroy <christophe.leroy@csgroup.eu>]

Le 24/06/2022 à 04:52, Paul E. McKenney a écrit :
> On Thu, Jun 23, 2022 at 04:50:49PM +0800, kernel test robot wrote:
>> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
>> head:   08897940f458ee55416cf80ab13d2d8b9f20038e
>> commit: 620ac34fef9e21aa2fd4aed6e01eed2e4fc605d4 [4204/5575] context_tracking: Convert state to atomic_t
>> config: powerpc-mgcoge_defconfig (https://download.01.org/0day-ci/archive/20220623/202206231654.cuANhsQq-lkp@intel.com/config)
>> compiler: powerpc-linux-gcc (GCC) 11.3.0
>> 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
>>          # https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?id=620ac34fef9e21aa2fd4aed6e01eed2e4fc605d4
>>          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 620ac34fef9e21aa2fd4aed6e01eed2e4fc605d4
>>          # save the config file
>>          mkdir build_dir && cp config build_dir/.config
>>          COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.3.0 make.cross W=1 O=build_dir ARCH=powerpc SHELL=/bin/bash arch/powerpc/kernel/
>>
>> If you fix the issue, kindly add following tag where applicable
>> Reported-by: kernel test robot <lkp@intel.com>
>>
>> All errors (new ones prefixed by >>):
>>
>>     arch/powerpc/kernel/interrupt.c: In function 'interrupt_exit_kernel_prepare':
>>>> arch/powerpc/kernel/interrupt.c:542:55: error: suggest braces around empty body in an 'if' statement [-Werror=empty-body]
>>       542 |                 CT_WARN_ON(ct_state() == CONTEXT_USER);
>>           |                                                       ^
>>     cc1: all warnings being treated as errors
> 
> This is a bit odd, and perhaps should instead be written as follows:
> 
> 	WARN_ON_ONCE(TRAP(regs) != INTERRUPT_PROGRAM && CT_WARN_ON(ct_state() == CONTEXT_USER));
> 
> But this code has been around for awhile, and was not changed by the
> commit called out above.  I will let the PowerPC guys choose what they
> want to do with it.


The commit called out above did a change. It added:

	#define CT_WARN_ON(cond)

When CONFIG_CONTEXT_TRACKING_USER is not defined


That change is wrong, it should be:

	#define CT_WARN_ON(cond)	do { } while (0)


Christophe