[PATCH] rcu-tasks: Fix compilation warning with !CONFIG_TASKS_RCU and CONFIG_TINY_RCU

[PATCH] rcu-tasks: Fix compilation warning with !CONFIG_TASKS_RCU and CONFIG_TINY_RCU

[Laurent Pinchart]

Commit 8344496e8b49 ("rcu-tasks: Conditionally compile
show_rcu_tasks_gp_kthreads()") introduced conditional compilation of
several functions, but forgot one occurrence of
show_rcu_tasks_classic_gp_kthread() that causes the compiler to warn of
an unused static function. Fix it.

Fixes: 8344496e8b49 ("rcu-tasks: Conditionally compile show_rcu_tasks_gp_kthreads()")
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
---
 kernel/rcu/tasks.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h
index 835e2df8590a..bddf3968c1eb 100644
--- a/kernel/rcu/tasks.h
+++ b/kernel/rcu/tasks.h
@@ -590,7 +590,9 @@ void exit_tasks_rcu_finish(void) __releases(&tasks_rcu_exit_srcu)
 }
 
 #else /* #ifdef CONFIG_TASKS_RCU */
+#ifndef CONFIG_TINY_RCU
 static void show_rcu_tasks_classic_gp_kthread(void) { }
+#endif /* #ifndef CONFIG_TINY_RCU */
 void exit_tasks_rcu_start(void) { }
 void exit_tasks_rcu_finish(void) { exit_tasks_rcu_finish_trace(current); }
 #endif /* #else #ifdef CONFIG_TASKS_RCU */
-- 
Regards,

Laurent Pinchart

Re: [PATCH] rcu-tasks: Fix compilation warning with !CONFIG_TASKS_RCU and CONFIG_TINY_RCU

[Paul E. McKenney]

On Sun, Aug 23, 2020 at 06:04:05AM +0300, Laurent Pinchart wrote:
> Commit 8344496e8b49 ("rcu-tasks: Conditionally compile
> show_rcu_tasks_gp_kthreads()") introduced conditional compilation of
> several functions, but forgot one occurrence of
> show_rcu_tasks_classic_gp_kthread() that causes the compiler to warn of
> an unused static function. Fix it.
> 
> Fixes: 8344496e8b49 ("rcu-tasks: Conditionally compile show_rcu_tasks_gp_kthreads()")
> Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> ---
>  kernel/rcu/tasks.h | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h
> index 835e2df8590a..bddf3968c1eb 100644
> --- a/kernel/rcu/tasks.h
> +++ b/kernel/rcu/tasks.h
> @@ -590,7 +590,9 @@ void exit_tasks_rcu_finish(void) __releases(&tasks_rcu_exit_srcu)
>  }
>  
>  #else /* #ifdef CONFIG_TASKS_RCU */
> +#ifndef CONFIG_TINY_RCU
>  static void show_rcu_tasks_classic_gp_kthread(void) { }
> +#endif /* #ifndef CONFIG_TINY_RCU */
>  void exit_tasks_rcu_start(void) { }
>  void exit_tasks_rcu_finish(void) { exit_tasks_rcu_finish_trace(current); }
>  #endif /* #else #ifdef CONFIG_TASKS_RCU */

Good catch!!!

But does the following addition of "static inline" work for you?

							Thanx, Paul

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

diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h
index 835e2df..3dc3ffc 100644
--- a/kernel/rcu/tasks.h
+++ b/kernel/rcu/tasks.h
@@ -590,9 +590,9 @@ void exit_tasks_rcu_finish(void) __releases(&tasks_rcu_exit_srcu)
 }
 
 #else /* #ifdef CONFIG_TASKS_RCU */
-static void show_rcu_tasks_classic_gp_kthread(void) { }
-void exit_tasks_rcu_start(void) { }
-void exit_tasks_rcu_finish(void) { exit_tasks_rcu_finish_trace(current); }
+static inline void show_rcu_tasks_classic_gp_kthread(void) { }
+static inline void exit_tasks_rcu_start(void) { }
+static inline void exit_tasks_rcu_finish(void) { exit_tasks_rcu_finish_trace(current); }
 #endif /* #else #ifdef CONFIG_TASKS_RCU */
 
 #ifdef CONFIG_TASKS_RUDE_RCU

Re: [PATCH] rcu-tasks: Fix compilation warning with !CONFIG_TASKS_RCU and CONFIG_TINY_RCU

[Laurent Pinchart]

Hi Paul,

On Tue, Aug 25, 2020 at 08:02:22AM -0700, Paul E. McKenney wrote:
> On Sun, Aug 23, 2020 at 06:04:05AM +0300, Laurent Pinchart wrote:
> > Commit 8344496e8b49 ("rcu-tasks: Conditionally compile
> > show_rcu_tasks_gp_kthreads()") introduced conditional compilation of
> > several functions, but forgot one occurrence of
> > show_rcu_tasks_classic_gp_kthread() that causes the compiler to warn of
> > an unused static function. Fix it.
> > 
> > Fixes: 8344496e8b49 ("rcu-tasks: Conditionally compile show_rcu_tasks_gp_kthreads()")
> > Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> > ---
> >  kernel/rcu/tasks.h | 2 ++
> >  1 file changed, 2 insertions(+)
> > 
> > diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h
> > index 835e2df8590a..bddf3968c1eb 100644
> > --- a/kernel/rcu/tasks.h
> > +++ b/kernel/rcu/tasks.h
> > @@ -590,7 +590,9 @@ void exit_tasks_rcu_finish(void) __releases(&tasks_rcu_exit_srcu)
> >  }
> >  
> >  #else /* #ifdef CONFIG_TASKS_RCU */
> > +#ifndef CONFIG_TINY_RCU
> >  static void show_rcu_tasks_classic_gp_kthread(void) { }
> > +#endif /* #ifndef CONFIG_TINY_RCU */
> >  void exit_tasks_rcu_start(void) { }
> >  void exit_tasks_rcu_finish(void) { exit_tasks_rcu_finish_trace(current); }
> >  #endif /* #else #ifdef CONFIG_TASKS_RCU */
> 
> Good catch!!!
> 
> But does the following addition of "static inline" work for you?

They do. I initially added a static inline, and realized #ifdef was used
extensively when trying to find the proper Fixes: tag, so I went for
that. I don't mind either way, as long as this gets fixed :-)

> ------------------------------------------------------------------------
> 
> diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h
> index 835e2df..3dc3ffc 100644
> --- a/kernel/rcu/tasks.h
> +++ b/kernel/rcu/tasks.h
> @@ -590,9 +590,9 @@ void exit_tasks_rcu_finish(void) __releases(&tasks_rcu_exit_srcu)
>  }
>  
>  #else /* #ifdef CONFIG_TASKS_RCU */
> -static void show_rcu_tasks_classic_gp_kthread(void) { }
> -void exit_tasks_rcu_start(void) { }
> -void exit_tasks_rcu_finish(void) { exit_tasks_rcu_finish_trace(current); }
> +static inline void show_rcu_tasks_classic_gp_kthread(void) { }
> +static inline void exit_tasks_rcu_start(void) { }
> +static inline void exit_tasks_rcu_finish(void) { exit_tasks_rcu_finish_trace(current); }
>  #endif /* #else #ifdef CONFIG_TASKS_RCU */
>  
>  #ifdef CONFIG_TASKS_RUDE_RCU

-- 
Regards,

Laurent Pinchart

Re: [PATCH] rcu-tasks: Fix compilation warning with !CONFIG_TASKS_RCU and CONFIG_TINY_RCU

[Paul E. McKenney]

On Tue, Aug 25, 2020 at 06:22:49PM +0300, Laurent Pinchart wrote:
> Hi Paul,
> 
> On Tue, Aug 25, 2020 at 08:02:22AM -0700, Paul E. McKenney wrote:
> > On Sun, Aug 23, 2020 at 06:04:05AM +0300, Laurent Pinchart wrote:
> > > Commit 8344496e8b49 ("rcu-tasks: Conditionally compile
> > > show_rcu_tasks_gp_kthreads()") introduced conditional compilation of
> > > several functions, but forgot one occurrence of
> > > show_rcu_tasks_classic_gp_kthread() that causes the compiler to warn of
> > > an unused static function. Fix it.
> > > 
> > > Fixes: 8344496e8b49 ("rcu-tasks: Conditionally compile show_rcu_tasks_gp_kthreads()")
> > > Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> > > ---
> > >  kernel/rcu/tasks.h | 2 ++
> > >  1 file changed, 2 insertions(+)
> > > 
> > > diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h
> > > index 835e2df8590a..bddf3968c1eb 100644
> > > --- a/kernel/rcu/tasks.h
> > > +++ b/kernel/rcu/tasks.h
> > > @@ -590,7 +590,9 @@ void exit_tasks_rcu_finish(void) __releases(&tasks_rcu_exit_srcu)
> > >  }
> > >  
> > >  #else /* #ifdef CONFIG_TASKS_RCU */
> > > +#ifndef CONFIG_TINY_RCU
> > >  static void show_rcu_tasks_classic_gp_kthread(void) { }
> > > +#endif /* #ifndef CONFIG_TINY_RCU */
> > >  void exit_tasks_rcu_start(void) { }
> > >  void exit_tasks_rcu_finish(void) { exit_tasks_rcu_finish_trace(current); }
> > >  #endif /* #else #ifdef CONFIG_TASKS_RCU */
> > 
> > Good catch!!!
> > 
> > But does the following addition of "static inline" work for you?
> 
> They do. I initially added a static inline, and realized #ifdef was used
> extensively when trying to find the proper Fixes: tag, so I went for
> that. I don't mind either way, as long as this gets fixed :-)

This is admittedly an odd .h file, given that it is included but once.

I have applied the following patch with your Reported-by, cc-ing -stable
for v5.8 and later.

							Thanx, Paul

> > ------------------------------------------------------------------------
> > 
> > diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h
> > index 835e2df..3dc3ffc 100644
> > --- a/kernel/rcu/tasks.h
> > +++ b/kernel/rcu/tasks.h
> > @@ -590,9 +590,9 @@ void exit_tasks_rcu_finish(void) __releases(&tasks_rcu_exit_srcu)
> >  }
> >  
> >  #else /* #ifdef CONFIG_TASKS_RCU */
> > -static void show_rcu_tasks_classic_gp_kthread(void) { }
> > -void exit_tasks_rcu_start(void) { }
> > -void exit_tasks_rcu_finish(void) { exit_tasks_rcu_finish_trace(current); }
> > +static inline void show_rcu_tasks_classic_gp_kthread(void) { }
> > +static inline void exit_tasks_rcu_start(void) { }
> > +static inline void exit_tasks_rcu_finish(void) { exit_tasks_rcu_finish_trace(current); }
> >  #endif /* #else #ifdef CONFIG_TASKS_RCU */
> >  
> >  #ifdef CONFIG_TASKS_RUDE_RCU
> 
> -- 
> Regards,
> 
> Laurent Pinchart

Re: [PATCH] rcu-tasks: Fix compilation warning with !CONFIG_TASKS_RCU and CONFIG_TINY_RCU

[Laurent Pinchart]

Hi Paul,

On Tue, Aug 25, 2020 at 09:16:29AM -0700, Paul E. McKenney wrote:
> On Tue, Aug 25, 2020 at 06:22:49PM +0300, Laurent Pinchart wrote:
> > On Tue, Aug 25, 2020 at 08:02:22AM -0700, Paul E. McKenney wrote:
> > > On Sun, Aug 23, 2020 at 06:04:05AM +0300, Laurent Pinchart wrote:
> > > > Commit 8344496e8b49 ("rcu-tasks: Conditionally compile
> > > > show_rcu_tasks_gp_kthreads()") introduced conditional compilation of
> > > > several functions, but forgot one occurrence of
> > > > show_rcu_tasks_classic_gp_kthread() that causes the compiler to warn of
> > > > an unused static function. Fix it.
> > > > 
> > > > Fixes: 8344496e8b49 ("rcu-tasks: Conditionally compile show_rcu_tasks_gp_kthreads()")
> > > > Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> > > > ---
> > > >  kernel/rcu/tasks.h | 2 ++
> > > >  1 file changed, 2 insertions(+)
> > > > 
> > > > diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h
> > > > index 835e2df8590a..bddf3968c1eb 100644
> > > > --- a/kernel/rcu/tasks.h
> > > > +++ b/kernel/rcu/tasks.h
> > > > @@ -590,7 +590,9 @@ void exit_tasks_rcu_finish(void) __releases(&tasks_rcu_exit_srcu)
> > > >  }
> > > >  
> > > >  #else /* #ifdef CONFIG_TASKS_RCU */
> > > > +#ifndef CONFIG_TINY_RCU
> > > >  static void show_rcu_tasks_classic_gp_kthread(void) { }
> > > > +#endif /* #ifndef CONFIG_TINY_RCU */
> > > >  void exit_tasks_rcu_start(void) { }
> > > >  void exit_tasks_rcu_finish(void) { exit_tasks_rcu_finish_trace(current); }
> > > >  #endif /* #else #ifdef CONFIG_TASKS_RCU */
> > > 
> > > Good catch!!!
> > > 
> > > But does the following addition of "static inline" work for you?
> > 
> > They do. I initially added a static inline, and realized #ifdef was used
> > extensively when trying to find the proper Fixes: tag, so I went for
> > that. I don't mind either way, as long as this gets fixed :-)
> 
> This is admittedly an odd .h file, given that it is included but once.
> 
> I have applied the following patch with your Reported-by, cc-ing -stable
> for v5.8 and later.

I don't see the fix in Linus' master branch. Given that 8344496e8b49 was
introduced in v5.9-rc1, shouldn't this be treated as a regression and
merged before Linus releases v5.9 ?

> > > ------------------------------------------------------------------------
> > > 
> > > diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h
> > > index 835e2df..3dc3ffc 100644
> > > --- a/kernel/rcu/tasks.h
> > > +++ b/kernel/rcu/tasks.h
> > > @@ -590,9 +590,9 @@ void exit_tasks_rcu_finish(void) __releases(&tasks_rcu_exit_srcu)
> > >  }
> > >  
> > >  #else /* #ifdef CONFIG_TASKS_RCU */
> > > -static void show_rcu_tasks_classic_gp_kthread(void) { }
> > > -void exit_tasks_rcu_start(void) { }
> > > -void exit_tasks_rcu_finish(void) { exit_tasks_rcu_finish_trace(current); }
> > > +static inline void show_rcu_tasks_classic_gp_kthread(void) { }
> > > +static inline void exit_tasks_rcu_start(void) { }
> > > +static inline void exit_tasks_rcu_finish(void) { exit_tasks_rcu_finish_trace(current); }
> > >  #endif /* #else #ifdef CONFIG_TASKS_RCU */
> > >  
> > >  #ifdef CONFIG_TASKS_RUDE_RCU

-- 
Regards,

Laurent Pinchart

Re: [PATCH] rcu-tasks: Fix compilation warning with !CONFIG_TASKS_RCU and CONFIG_TINY_RCU

[Paul E. McKenney]

On Fri, Sep 18, 2020 at 01:26:41AM +0300, Laurent Pinchart wrote:
> Hi Paul,
> 
> On Tue, Aug 25, 2020 at 09:16:29AM -0700, Paul E. McKenney wrote:
> > On Tue, Aug 25, 2020 at 06:22:49PM +0300, Laurent Pinchart wrote:
> > > On Tue, Aug 25, 2020 at 08:02:22AM -0700, Paul E. McKenney wrote:
> > > > On Sun, Aug 23, 2020 at 06:04:05AM +0300, Laurent Pinchart wrote:
> > > > > Commit 8344496e8b49 ("rcu-tasks: Conditionally compile
> > > > > show_rcu_tasks_gp_kthreads()") introduced conditional compilation of
> > > > > several functions, but forgot one occurrence of
> > > > > show_rcu_tasks_classic_gp_kthread() that causes the compiler to warn of
> > > > > an unused static function. Fix it.
> > > > > 
> > > > > Fixes: 8344496e8b49 ("rcu-tasks: Conditionally compile show_rcu_tasks_gp_kthreads()")
> > > > > Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> > > > > ---
> > > > >  kernel/rcu/tasks.h | 2 ++
> > > > >  1 file changed, 2 insertions(+)
> > > > > 
> > > > > diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h
> > > > > index 835e2df8590a..bddf3968c1eb 100644
> > > > > --- a/kernel/rcu/tasks.h
> > > > > +++ b/kernel/rcu/tasks.h
> > > > > @@ -590,7 +590,9 @@ void exit_tasks_rcu_finish(void) __releases(&tasks_rcu_exit_srcu)
> > > > >  }
> > > > >  
> > > > >  #else /* #ifdef CONFIG_TASKS_RCU */
> > > > > +#ifndef CONFIG_TINY_RCU
> > > > >  static void show_rcu_tasks_classic_gp_kthread(void) { }
> > > > > +#endif /* #ifndef CONFIG_TINY_RCU */
> > > > >  void exit_tasks_rcu_start(void) { }
> > > > >  void exit_tasks_rcu_finish(void) { exit_tasks_rcu_finish_trace(current); }
> > > > >  #endif /* #else #ifdef CONFIG_TASKS_RCU */
> > > > 
> > > > Good catch!!!
> > > > 
> > > > But does the following addition of "static inline" work for you?
> > > 
> > > They do. I initially added a static inline, and realized #ifdef was used
> > > extensively when trying to find the proper Fixes: tag, so I went for
> > > that. I don't mind either way, as long as this gets fixed :-)
> > 
> > This is admittedly an odd .h file, given that it is included but once.
> > 
> > I have applied the following patch with your Reported-by, cc-ing -stable
> > for v5.8 and later.
> 
> I don't see the fix in Linus' master branch. Given that 8344496e8b49 was
> introduced in v5.9-rc1, shouldn't this be treated as a regression and
> merged before Linus releases v5.9 ?

The current plan is that it goes in during the upcoming merge window,
a few weeks from now.  However, it sounds like you need it sooner.
I will try doing a pull request and see what happens.

							Thanx, Paul

> > > > ------------------------------------------------------------------------
> > > > 
> > > > diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h
> > > > index 835e2df..3dc3ffc 100644
> > > > --- a/kernel/rcu/tasks.h
> > > > +++ b/kernel/rcu/tasks.h
> > > > @@ -590,9 +590,9 @@ void exit_tasks_rcu_finish(void) __releases(&tasks_rcu_exit_srcu)
> > > >  }
> > > >  
> > > >  #else /* #ifdef CONFIG_TASKS_RCU */
> > > > -static void show_rcu_tasks_classic_gp_kthread(void) { }
> > > > -void exit_tasks_rcu_start(void) { }
> > > > -void exit_tasks_rcu_finish(void) { exit_tasks_rcu_finish_trace(current); }
> > > > +static inline void show_rcu_tasks_classic_gp_kthread(void) { }
> > > > +static inline void exit_tasks_rcu_start(void) { }
> > > > +static inline void exit_tasks_rcu_finish(void) { exit_tasks_rcu_finish_trace(current); }
> > > >  #endif /* #else #ifdef CONFIG_TASKS_RCU */
> > > >  
> > > >  #ifdef CONFIG_TASKS_RUDE_RCU
> 
> -- 
> Regards,
> 
> Laurent Pinchart

Re: [PATCH] rcu-tasks: Fix compilation warning with !CONFIG_TASKS_RCU and CONFIG_TINY_RCU

[Paul E. McKenney]

On Thu, Sep 17, 2020 at 04:24:16PM -0700, Paul E. McKenney wrote:
> On Fri, Sep 18, 2020 at 01:26:41AM +0300, Laurent Pinchart wrote:
> > Hi Paul,
> > 
> > On Tue, Aug 25, 2020 at 09:16:29AM -0700, Paul E. McKenney wrote:
> > > On Tue, Aug 25, 2020 at 06:22:49PM +0300, Laurent Pinchart wrote:
> > > > On Tue, Aug 25, 2020 at 08:02:22AM -0700, Paul E. McKenney wrote:
> > > > > On Sun, Aug 23, 2020 at 06:04:05AM +0300, Laurent Pinchart wrote:
> > > > > > Commit 8344496e8b49 ("rcu-tasks: Conditionally compile
> > > > > > show_rcu_tasks_gp_kthreads()") introduced conditional compilation of
> > > > > > several functions, but forgot one occurrence of
> > > > > > show_rcu_tasks_classic_gp_kthread() that causes the compiler to warn of
> > > > > > an unused static function. Fix it.
> > > > > > 
> > > > > > Fixes: 8344496e8b49 ("rcu-tasks: Conditionally compile show_rcu_tasks_gp_kthreads()")
> > > > > > Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> > > > > > ---
> > > > > >  kernel/rcu/tasks.h | 2 ++
> > > > > >  1 file changed, 2 insertions(+)
> > > > > > 
> > > > > > diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h
> > > > > > index 835e2df8590a..bddf3968c1eb 100644
> > > > > > --- a/kernel/rcu/tasks.h
> > > > > > +++ b/kernel/rcu/tasks.h
> > > > > > @@ -590,7 +590,9 @@ void exit_tasks_rcu_finish(void) __releases(&tasks_rcu_exit_srcu)
> > > > > >  }
> > > > > >  
> > > > > >  #else /* #ifdef CONFIG_TASKS_RCU */
> > > > > > +#ifndef CONFIG_TINY_RCU
> > > > > >  static void show_rcu_tasks_classic_gp_kthread(void) { }
> > > > > > +#endif /* #ifndef CONFIG_TINY_RCU */
> > > > > >  void exit_tasks_rcu_start(void) { }
> > > > > >  void exit_tasks_rcu_finish(void) { exit_tasks_rcu_finish_trace(current); }
> > > > > >  #endif /* #else #ifdef CONFIG_TASKS_RCU */
> > > > > 
> > > > > Good catch!!!
> > > > > 
> > > > > But does the following addition of "static inline" work for you?
> > > > 
> > > > They do. I initially added a static inline, and realized #ifdef was used
> > > > extensively when trying to find the proper Fixes: tag, so I went for
> > > > that. I don't mind either way, as long as this gets fixed :-)
> > > 
> > > This is admittedly an odd .h file, given that it is included but once.
> > > 
> > > I have applied the following patch with your Reported-by, cc-ing -stable
> > > for v5.8 and later.
> > 
> > I don't see the fix in Linus' master branch. Given that 8344496e8b49 was
> > introduced in v5.9-rc1, shouldn't this be treated as a regression and
> > merged before Linus releases v5.9 ?
> 
> The current plan is that it goes in during the upcoming merge window,
> a few weeks from now.  However, it sounds like you need it sooner.
> I will try doing a pull request and see what happens.

And sent, CCing you.

							Thanx, Paul

> > > > > ------------------------------------------------------------------------
> > > > > 
> > > > > diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h
> > > > > index 835e2df..3dc3ffc 100644
> > > > > --- a/kernel/rcu/tasks.h
> > > > > +++ b/kernel/rcu/tasks.h
> > > > > @@ -590,9 +590,9 @@ void exit_tasks_rcu_finish(void) __releases(&tasks_rcu_exit_srcu)
> > > > >  }
> > > > >  
> > > > >  #else /* #ifdef CONFIG_TASKS_RCU */
> > > > > -static void show_rcu_tasks_classic_gp_kthread(void) { }
> > > > > -void exit_tasks_rcu_start(void) { }
> > > > > -void exit_tasks_rcu_finish(void) { exit_tasks_rcu_finish_trace(current); }
> > > > > +static inline void show_rcu_tasks_classic_gp_kthread(void) { }
> > > > > +static inline void exit_tasks_rcu_start(void) { }
> > > > > +static inline void exit_tasks_rcu_finish(void) { exit_tasks_rcu_finish_trace(current); }
> > > > >  #endif /* #else #ifdef CONFIG_TASKS_RCU */
> > > > >  
> > > > >  #ifdef CONFIG_TASKS_RUDE_RCU
> > 
> > -- 
> > Regards,
> > 
> > Laurent Pinchart

Re: [PATCH] rcu-tasks: Fix compilation warning with !CONFIG_TASKS_RCU and CONFIG_TINY_RCU

[Laurent Pinchart]

On Mon, Sep 21, 2020 at 12:37:18PM -0700, Paul E. McKenney wrote:
> On Thu, Sep 17, 2020 at 04:24:16PM -0700, Paul E. McKenney wrote:
> > On Fri, Sep 18, 2020 at 01:26:41AM +0300, Laurent Pinchart wrote:
> > > Hi Paul,
> > > 
> > > On Tue, Aug 25, 2020 at 09:16:29AM -0700, Paul E. McKenney wrote:
> > > > On Tue, Aug 25, 2020 at 06:22:49PM +0300, Laurent Pinchart wrote:
> > > > > On Tue, Aug 25, 2020 at 08:02:22AM -0700, Paul E. McKenney wrote:
> > > > > > On Sun, Aug 23, 2020 at 06:04:05AM +0300, Laurent Pinchart wrote:
> > > > > > > Commit 8344496e8b49 ("rcu-tasks: Conditionally compile
> > > > > > > show_rcu_tasks_gp_kthreads()") introduced conditional compilation of
> > > > > > > several functions, but forgot one occurrence of
> > > > > > > show_rcu_tasks_classic_gp_kthread() that causes the compiler to warn of
> > > > > > > an unused static function. Fix it.
> > > > > > > 
> > > > > > > Fixes: 8344496e8b49 ("rcu-tasks: Conditionally compile show_rcu_tasks_gp_kthreads()")
> > > > > > > Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> > > > > > > ---
> > > > > > >  kernel/rcu/tasks.h | 2 ++
> > > > > > >  1 file changed, 2 insertions(+)
> > > > > > > 
> > > > > > > diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h
> > > > > > > index 835e2df8590a..bddf3968c1eb 100644
> > > > > > > --- a/kernel/rcu/tasks.h
> > > > > > > +++ b/kernel/rcu/tasks.h
> > > > > > > @@ -590,7 +590,9 @@ void exit_tasks_rcu_finish(void) __releases(&tasks_rcu_exit_srcu)
> > > > > > >  }
> > > > > > >  
> > > > > > >  #else /* #ifdef CONFIG_TASKS_RCU */
> > > > > > > +#ifndef CONFIG_TINY_RCU
> > > > > > >  static void show_rcu_tasks_classic_gp_kthread(void) { }
> > > > > > > +#endif /* #ifndef CONFIG_TINY_RCU */
> > > > > > >  void exit_tasks_rcu_start(void) { }
> > > > > > >  void exit_tasks_rcu_finish(void) { exit_tasks_rcu_finish_trace(current); }
> > > > > > >  #endif /* #else #ifdef CONFIG_TASKS_RCU */
> > > > > > 
> > > > > > Good catch!!!
> > > > > > 
> > > > > > But does the following addition of "static inline" work for you?
> > > > > 
> > > > > They do. I initially added a static inline, and realized #ifdef was used
> > > > > extensively when trying to find the proper Fixes: tag, so I went for
> > > > > that. I don't mind either way, as long as this gets fixed :-)
> > > > 
> > > > This is admittedly an odd .h file, given that it is included but once.
> > > > 
> > > > I have applied the following patch with your Reported-by, cc-ing -stable
> > > > for v5.8 and later.
> > > 
> > > I don't see the fix in Linus' master branch. Given that 8344496e8b49 was
> > > introduced in v5.9-rc1, shouldn't this be treated as a regression and
> > > merged before Linus releases v5.9 ?
> > 
> > The current plan is that it goes in during the upcoming merge window,
> > a few weeks from now.  However, it sounds like you need it sooner.
> > I will try doing a pull request and see what happens.
> 
> And sent, CCing you.

Thank you :-)

> > > > > > ------------------------------------------------------------------------
> > > > > > 
> > > > > > diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h
> > > > > > index 835e2df..3dc3ffc 100644
> > > > > > --- a/kernel/rcu/tasks.h
> > > > > > +++ b/kernel/rcu/tasks.h
> > > > > > @@ -590,9 +590,9 @@ void exit_tasks_rcu_finish(void) __releases(&tasks_rcu_exit_srcu)
> > > > > >  }
> > > > > >  
> > > > > >  #else /* #ifdef CONFIG_TASKS_RCU */
> > > > > > -static void show_rcu_tasks_classic_gp_kthread(void) { }
> > > > > > -void exit_tasks_rcu_start(void) { }
> > > > > > -void exit_tasks_rcu_finish(void) { exit_tasks_rcu_finish_trace(current); }
> > > > > > +static inline void show_rcu_tasks_classic_gp_kthread(void) { }
> > > > > > +static inline void exit_tasks_rcu_start(void) { }
> > > > > > +static inline void exit_tasks_rcu_finish(void) { exit_tasks_rcu_finish_trace(current); }
> > > > > >  #endif /* #else #ifdef CONFIG_TASKS_RCU */
> > > > > >  
> > > > > >  #ifdef CONFIG_TASKS_RUDE_RCU

-- 
Regards,

Laurent Pinchart