Re: [PATCH] ftrace: Fix stack trace entry generated by ftrace_pid_func()

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On Sun, 26 May 2024 22:51:53 +0800
kernel test robot <lkp@xxxxxxxxx> wrote:

> Hi Tatsuya,
> 
> kernel test robot noticed the following build warnings:
> 
> [auto build test WARNING on linus/master]
> [also build test WARNING on rostedt-trace/for-next v6.9 next-20240523]
> [cannot apply to rostedt-trace/for-next-urgent]
> [If your patch is applied to the wrong git tree, kindly drop us a note.
> And when submitting patch, we suggest to use '--base' as documented in
> https://git-scm.com/docs/git-format-patch#_base_tree_information]
> 
> url:    https://github.com/intel-lab-lkp/linux/commits/Tatsuya-S/ftrace-Fix-stack-trace-entry-generated-by-ftrace_pid_func/20240526-193149
> base:   linus/master
> patch link:    https://lore.kernel.org/r/20240526112658.46740-1-tatsuya.s2862%40gmail.com
> patch subject: [PATCH] ftrace: Fix stack trace entry generated by ftrace_pid_func()
> config: x86_64-buildonly-randconfig-002-20240526 (https://download.01.org/0day-ci/archive/20240526/202405262232.L4XH8q6O-lkp@xxxxxxxxx/config)
> compiler: clang version 18.1.5 (https://github.com/llvm/llvm-project 617a15a9eac96088ae5e9134248d8236e34b91b1)
> reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240526/202405262232.L4XH8q6O-lkp@xxxxxxxxx/reproduce)
> 
> If you fix the issue in a separate patch/commit (i.e. not just a new version of
> the same patch/commit), kindly add following tags
> | Reported-by: kernel test robot <lkp@xxxxxxxxx>
> | Closes: https://lore.kernel.org/oe-kbuild-all/202405262232.L4XH8q6O-lkp@xxxxxxxxx/
> 
> All warnings (new ones prefixed by >>):
> 
> >> kernel/trace/ftrace.c:102:6: warning: no previous prototype for function 'ftrace_pids_enabled' [-Wmissing-prototypes]
>      102 | bool ftrace_pids_enabled(struct ftrace_ops *ops)
>          |      ^
>    kernel/trace/ftrace.c:102:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
>      102 | bool ftrace_pids_enabled(struct ftrace_ops *ops)
>          | ^
>          | static 
>    1 warning generated.

This is because the prototype in linux/ftrace.h is placed in the 
#ifdef CONFIG_DYNAMIC_FTRACE block. The prototype needs to be moved
outside of the block.

Thank you,

> 
> 
> vim +/ftrace_pids_enabled +102 kernel/trace/ftrace.c
> 
>    101	
>  > 102	bool ftrace_pids_enabled(struct ftrace_ops *ops)
>    103	{
>    104		struct trace_array *tr;
>    105	
>    106		if (!(ops->flags & FTRACE_OPS_FL_PID) || !ops->private)
>    107			return false;
>    108	
>    109		tr = ops->private;
>    110	
>    111		return tr->function_pids != NULL || tr->function_no_pids != NULL;
>    112	}
>    113	
> 
> -- 
> 0-DAY CI Kernel Test Service
> https://github.com/intel/lkp-tests/wiki


-- 
Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>