Re: [linux-next:master 4044/9592] arch/arm/kernel/ftrace.c:229:6: warning: no previous prototype for function 'prepare_ftrace_return'

"Chen, Rong A" <rong.a.chen@xxxxxxxxx> · Wed, 2 Mar 2022 14:35:41 +0800

On 3/2/2022 2:15 PM, Ard Biesheuvel wrote:
(cc Rong Chen)

On Wed, 2 Mar 2022 at 03:52, kernel test robot <lkp@xxxxxxxxx> wrote:

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
head:   e6ada6df471f847da3b09b357e246c62335bc0bb
commit: 41918ec82eb6f80c8b401422f27ca76c85aa0cb7 [4044/9592] ARM: ftrace: enable the graph tracer with the EABI unwinder
config: arm-bcm2835_defconfig (https://download.01.org/0day-ci/archive/20220302/202203020913.I6LbmH7l-lkp@xxxxxxxxx/config)
compiler: clang version 15.0.0 (https://github.com/llvm/llvm-project d271fc04d5b97b12e6b797c6067d3c96a8d7470e)
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 arm cross compiling tool for clang build
         # apt-get install binutils-arm-linux-gnueabi
         # https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?id=41918ec82eb6f80c8b401422f27ca76c85aa0cb7
         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 41918ec82eb6f80c8b401422f27ca76c85aa0cb7
         # save the config file to linux build tree
         mkdir build_dir
         COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=arm SHELL=/bin/bash arch/arm/kernel/

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@xxxxxxxxx>

All warnings (new ones prefixed by >>):

arch/arm/kernel/ftrace.c:229:6: warning: no previous prototype for function 'prepare_ftrace_return' [-Wmissing-prototypes]
    void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
         ^
    arch/arm/kernel/ftrace.c:229:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
    void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
    ^
    static
    1 warning generated.

This function is asmlinkage so why is this still being reported?

Hi Ard,

Thanks for the information, we only checked 'asmlinkage' from warning 
messages:

  >>>> arch/arm/kernel/ftrace.c:229:6: warning: no previous prototype 
for function 'prepare_ftrace_return' [-Wmissing-prototypes]
>>     void prepare_ftrace_return(unsigned long *parent, unsigned long 
self_addr,

but actually 'asmlinkage' is in another line:

   asmlinkage
   void prepare_ftrace_return(unsigned long *parent, unsigned long 
self_addr,

we missed this kind of problem, I'll take a look at it.

Best Regards,
Rong Chen