Re: [paulmck-rcu:rcu/next 19/19] kernel/rcu/rcuscale.c:340:20: error: use of undeclared identifier 'get_rcu_tasks_trace_gp_kthread'; did you mean 'show_rcu_tasks_trace_gp_kthread'?

[Paul E. McKenney]

On Fri, May 19, 2023 at 02:30:11AM +0800, kernel test robot wrote:
> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git rcu/next
> head:   9bb839a83e1bbbfd4f7f20827aafd0a39fad00c7
> commit: 9bb839a83e1bbbfd4f7f20827aafd0a39fad00c7 [19/19] rcuscale: Measure grace-period kthread CPU time
> config: x86_64-randconfig-a001
> compiler: clang version 14.0.6 (https://github.com/llvm/llvm-project f28c006a5895fc0e329fe15fead81e37457cb1d1)
> 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/paulmck/linux-rcu.git/commit/?id=9bb839a83e1bbbfd4f7f20827aafd0a39fad00c7
>         git remote add paulmck-rcu https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git
>         git fetch --no-tags paulmck-rcu rcu/next
>         git checkout 9bb839a83e1bbbfd4f7f20827aafd0a39fad00c7
>         # save the config file
>         mkdir build_dir && cp config build_dir/.config
>         COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=x86_64 olddefconfig
>         COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash kernel/rcu/
> 
> If you fix the issue, kindly add following tag where applicable
> | Reported-by: kernel test robot <lkp@xxxxxxxxx>
> | Closes: https://lore.kernel.org/oe-kbuild-all/202305190259.Rm6JC6Nz-lkp@xxxxxxxxx/
> 
> All errors (new ones prefixed by >>):
> 
> >> kernel/rcu/rcuscale.c:340:20: error: use of undeclared identifier 'get_rcu_tasks_trace_gp_kthread'; did you mean 'show_rcu_tasks_trace_gp_kthread'?
>            .rso_gp_kthread = get_rcu_tasks_trace_gp_kthread,
>                              ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>                              show_rcu_tasks_trace_gp_kthread
>    kernel/rcu/rcu.h:642:20: note: 'show_rcu_tasks_trace_gp_kthread' declared here
>    static inline void show_rcu_tasks_trace_gp_kthread(void) {}
>                       ^
> >> kernel/rcu/rcuscale.c:340:20: error: incompatible function pointer types initializing 'struct task_struct *(*)(void)' with an expression of type 'void (void)' [-Werror,-Wincompatible-function-pointer-types]
>            .rso_gp_kthread = get_rcu_tasks_trace_gp_kthread,
>                              ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>    2 errors generated.

Apologies for the hassle!  Does the diff below help at your end?

						Thaxn, Paul

------------------------------------------------------------------------

diff --git a/include/linux/rcupdate_trace.h b/include/linux/rcupdate_trace.h
index 3a5a322939b6..eda493200663 100644
--- a/include/linux/rcupdate_trace.h
+++ b/include/linux/rcupdate_trace.h
@@ -87,9 +87,7 @@ static inline void rcu_read_unlock_trace(void)
 void call_rcu_tasks_trace(struct rcu_head *rhp, rcu_callback_t func);
 void synchronize_rcu_tasks_trace(void);
 void rcu_barrier_tasks_trace(void);
-# ifdef CONFIG_RCU_SCALE_TEST
 struct task_struct *get_rcu_tasks_trace_gp_kthread(void);
-# endif
 #else
 /*
  * The BPF JIT forms these addresses even when it doesn't call these