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 26, 2023 at 03:23:47PM +0800, Yujie Liu wrote:
> Hi Paul,
> 
> On Thu, May 18, 2023 at 07:11:33PM -0700, Paul E. McKenney wrote:
> > 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?
> 
> Sorry for the late reply. We noticed that rcu/next branch was respined
> and the diff below has been applied. We tested the new head commit
> 60901dadfadc ("rcuscale: Measure grace-period kthread CPU time")
> and the build error is gone. Thanks.
> 
> Tested-by: Yujie Liu <yujie.liu@xxxxxxxxx>

Very good, thank you!  I will apply on my next rebase.


						Thanx, 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
> >