Re: [PATCH] rcuscale: fix building with RCU_TINY

[Paul E. McKenney]

On Tue, Jun 13, 2023 at 07:42:17AM -0700, Randy Dunlap wrote:
> Paul-
> 
> On 6/9/23 15:51, Paul E. McKenney wrote:
> > On Fri, Jun 09, 2023 at 02:05:14PM +0200, Arnd Bergmann wrote:
> >> From: Arnd Bergmann <arnd@xxxxxxxx>
> >>
> >> Both the CONFIG_TASKS_RCU and CONFIG_TASKS_RUDE_RCU options
> >> are broken when RCU_TINY is enabled as well, as some functions
> >> are missing a declaration.
> >>
> >> In file included from kernel/rcu/update.c:649:
> >> kernel/rcu/tasks.h:1271:21: error: no previous prototype for 'get_rcu_tasks_rude_gp_kthread' [-Werror=missing-prototypes]
> >>  1271 | struct task_struct *get_rcu_tasks_rude_gp_kthread(void)
> >>       |                     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> >> kernel/rcu/rcuscale.c:330:27: error: 'get_rcu_tasks_rude_gp_kthread' undeclared here (not in a function); did you mean 'get_rcu_tasks_trace_gp_kthread'?
> >>   330 |         .rso_gp_kthread = get_rcu_tasks_rude_gp_kthread,
> >>       |                           ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> >>       |                           get_rcu_tasks_trace_gp_kthread
> >>
> >> In file included from /home/arnd/arm-soc/kernel/rcu/update.c:649:
> >> kernel/rcu/tasks.h:1113:21: error: no previous prototype for 'get_rcu_tasks_gp_kthread' [-Werror=missing-prototypes]
> >>  1113 | struct task_struct *get_rcu_tasks_gp_kthread(void)
> >>       |                     ^~~~~~~~~~~~~~~~~~~~~~~~
> >>
> >> Also, building with CONFIG_TASKS_RUDE_RCU but not CONFIG_TASKS_RCU is
> >> broken because of some missing stub functions:
> >>
> >> kernel/rcu/rcuscale.c:322:27: error: 'tasks_scale_read_lock' undeclared here (not in a function); did you mean 'srcu_scale_read_lock'?
> >>   322 |         .readlock       = tasks_scale_read_lock,
> >>       |                           ^~~~~~~~~~~~~~~~~~~~~
> >>       |                           srcu_scale_read_lock
> >> kernel/rcu/rcuscale.c:323:27: error: 'tasks_scale_read_unlock' undeclared here (not in a function); did you mean 'srcu_scale_read_unlock'?
> >>   323 |         .readunlock     = tasks_scale_read_unlock,
> >>       |                           ^~~~~~~~~~~~~~~~~~~~~~~
> >>       |                           srcu_scale_read_unlock
> >>
> >> Move the declarations outside of the RCU_TINY #ifdef and duplicate the
> >> shared stub functions to address all of the above.
> >>
> >> Fixes: 88d7ff818f0ce ("rcuscale: Add RCU Tasks Rude testing")
> >> Fixes: 755f1c5eb416b ("rcuscale: Measure RCU Tasks Trace grace-period kthread CPU time")
> >> Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
> > 
> > Queued and pushed, thank you!
> > 
> > I clearly need to improve my Kconfig coverage here...
> 
> Pushed where. I'm still seeing this build error in linux-next 20230613.

To rcu/dev.  There have been some testing bottlenecks, but it should
reach rcu/next soon.

							Thanx, Paul

> Thanks.
> 
> > 
> >> ---
> >>  kernel/rcu/rcu.h      | 14 ++++++++------
> >>  kernel/rcu/rcuscale.c | 13 +++++++++++--
> >>  2 files changed, 19 insertions(+), 8 deletions(-)
> >>
> >> diff --git a/kernel/rcu/rcu.h b/kernel/rcu/rcu.h
> >> index 9829d8161b213..5befd8780dcd3 100644
> >> --- a/kernel/rcu/rcu.h
> >> +++ b/kernel/rcu/rcu.h
> >> @@ -505,18 +505,20 @@ void rcu_async_relax(void);
> >>  void rcupdate_announce_bootup_oddness(void);
> >>  #ifdef CONFIG_TASKS_RCU_GENERIC
> >>  void show_rcu_tasks_gp_kthreads(void);
> >> -# ifdef CONFIG_TASKS_RCU
> >> -struct task_struct *get_rcu_tasks_gp_kthread(void);
> >> -# endif // # ifdef CONFIG_TASKS_RCU
> >> -# ifdef CONFIG_TASKS_RUDE_RCU
> >> -struct task_struct *get_rcu_tasks_rude_gp_kthread(void);
> >> -# endif // # ifdef CONFIG_TASKS_RUDE_RCU
> >>  #else /* #ifdef CONFIG_TASKS_RCU_GENERIC */
> >>  static inline void show_rcu_tasks_gp_kthreads(void) {}
> >>  #endif /* #else #ifdef CONFIG_TASKS_RCU_GENERIC */
> >>  void rcu_request_urgent_qs_task(struct task_struct *t);
> >>  #endif /* #else #ifdef CONFIG_TINY_RCU */
> >>  
> >> +#ifdef CONFIG_TASKS_RCU
> >> +struct task_struct *get_rcu_tasks_gp_kthread(void);
> >> +#endif // # ifdef CONFIG_TASKS_RCU
> >> +
> >> +#ifdef CONFIG_TASKS_RUDE_RCU
> >> +struct task_struct *get_rcu_tasks_rude_gp_kthread(void);
> >> +#endif // # ifdef CONFIG_TASKS_RUDE_RCU
> >> +
> >>  #define RCU_SCHEDULER_INACTIVE	0
> >>  #define RCU_SCHEDULER_INIT	1
> >>  #define RCU_SCHEDULER_RUNNING	2
> >> diff --git a/kernel/rcu/rcuscale.c b/kernel/rcu/rcuscale.c
> >> index 5ce3b4e7ce711..a0eae19007088 100644
> >> --- a/kernel/rcu/rcuscale.c
> >> +++ b/kernel/rcu/rcuscale.c
> >> @@ -316,11 +316,20 @@ static struct rcu_scale_ops tasks_ops = {
> >>   * Definitions for RCU-tasks-rude scalability testing.
> >>   */
> >>  
> >> +static int tasks_rude_scale_read_lock(void)
> >> +{
> >> +	return 0;
> >> +}
> >> +
> >> +static void tasks_rude_scale_read_unlock(int idx)
> >> +{
> >> +}
> >> +
> >>  static struct rcu_scale_ops tasks_rude_ops = {
> >>  	.ptype		= RCU_TASKS_RUDE_FLAVOR,
> >>  	.init		= rcu_sync_scale_init,
> >> -	.readlock	= tasks_scale_read_lock,
> >> -	.readunlock	= tasks_scale_read_unlock,
> >> +	.readlock	= tasks_rude_scale_read_lock,
> >> +	.readunlock	= tasks_rude_scale_read_unlock,
> >>  	.get_gp_seq	= rcu_no_completed,
> >>  	.gp_diff	= rcu_seq_diff,
> >>  	.async		= call_rcu_tasks_rude,
> >> -- 
> >> 2.39.2
> >>
> 
> -- 
> ~Randy