[PATCH] rcutorture: fix missing function at build time

[PATCH] rcutorture: fix missing function at build time

[Luis Claudio R. Goncalves]

Hello,

This is a minor issue, but as I seem to have woken up Paul at 4AM with the
many beeps from IRC I would feel bad if I did not send this patch to the
list. Actually, as that patch has been sitting on my computer for a few
days now, i already feel bad :)


rcutorture: fix missing function at build time

Trying to build the rcutorture module on 3.18.7-rt2 ends up on:

   ERROR: "rcu_force_quiescent_state" [kernel/rcu/rcutorture.ko] undefined!

Commit "71d22b5 Subject: rcu: Merge RCU-bh into RCU-preempt" encloses three
functions (rcu_batches_completed_bh, rcu_force_quiescent_state and
rcu_bh_force_quiescent_state) on an #ifndef CONFIG_PREEMPT_RT_FULL / #endif
pair, rendering them non-existent on RT. As the commit points out, that was
a wise and necessary move.

But in order to get rcutorture build working again we need to define an
empty rcu_force_quiescent_state function.

Signed-off-by: Luis Claudio R. Goncalves <lclaudio@uudg.org>

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index a4e9e25..28a54f6 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -378,6 +378,11 @@ void rcu_bh_force_quiescent_state(void)
 	force_quiescent_state(&rcu_bh_state);
 }
 EXPORT_SYMBOL_GPL(rcu_bh_force_quiescent_state);
+#else
+void rcu_force_quiescent_state(void)
+{
+}
+EXPORT_SYMBOL_GPL(rcu_force_quiescent_state);
 #endif
 
 /*

-- 
[ Luis Claudio R. Goncalves                    Bass - Gospel - RT ]
[ Fingerprint: 4FDD B8C4 3C59 34BD 8BE9  2696 7203 D980 A448 C8F8 ]

Re: [PATCH] rcutorture: fix missing function at build time

[Paul E. McKenney]

On Mon, Mar 02, 2015 at 05:15:31PM -0300, Luis Claudio R. Goncalves wrote:
> Hello,
> 
> This is a minor issue, but as I seem to have woken up Paul at 4AM with the
> many beeps from IRC I would feel bad if I did not send this patch to the
> list. Actually, as that patch has been sitting on my computer for a few
> days now, i already feel bad :)

Actually, you did not wake me up -- I had accidentally left my system
logged into IRC overnight and saw your post when I woke up some time
later.  ;-)

> rcutorture: fix missing function at build time
> 
> Trying to build the rcutorture module on 3.18.7-rt2 ends up on:
> 
>    ERROR: "rcu_force_quiescent_state" [kernel/rcu/rcutorture.ko] undefined!
> 
> Commit "71d22b5 Subject: rcu: Merge RCU-bh into RCU-preempt" encloses three
> functions (rcu_batches_completed_bh, rcu_force_quiescent_state and
> rcu_bh_force_quiescent_state) on an #ifndef CONFIG_PREEMPT_RT_FULL / #endif
> pair, rendering them non-existent on RT. As the commit points out, that was
> a wise and necessary move.
> 
> But in order to get rcutorture build working again we need to define an
> empty rcu_force_quiescent_state function.
> 
> Signed-off-by: Luis Claudio R. Goncalves <lclaudio@uudg.org>
> 
> diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
> index a4e9e25..28a54f6 100644
> --- a/kernel/rcu/tree.c
> +++ b/kernel/rcu/tree.c
> @@ -378,6 +378,11 @@ void rcu_bh_force_quiescent_state(void)
>  	force_quiescent_state(&rcu_bh_state);
>  }
>  EXPORT_SYMBOL_GPL(rcu_bh_force_quiescent_state);
> +#else
> +void rcu_force_quiescent_state(void)
> +{
> +}
> +EXPORT_SYMBOL_GPL(rcu_force_quiescent_state);

This is -rt only, correct?

							Thanx, Paul

>  #endif
> 
>  /*
> 
> -- 
> [ Luis Claudio R. Goncalves                    Bass - Gospel - RT ]
> [ Fingerprint: 4FDD B8C4 3C59 34BD 8BE9  2696 7203 D980 A448 C8F8 ]
> 

Re: [PATCH] rcutorture: fix missing function at build time

[Luis Claudio R. Goncalves]

On Mon, Mar 02, 2015 at 01:18:15PM -0800, Paul E. McKenney wrote:
...
| > diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
| > index a4e9e25..28a54f6 100644
| > --- a/kernel/rcu/tree.c
| > +++ b/kernel/rcu/tree.c
| > @@ -378,6 +378,11 @@ void rcu_bh_force_quiescent_state(void)
| >  	force_quiescent_state(&rcu_bh_state);
| >  }
| >  EXPORT_SYMBOL_GPL(rcu_bh_force_quiescent_state);
| > +#else
| > +void rcu_force_quiescent_state(void)
| > +{
| > +}
| > +EXPORT_SYMBOL_GPL(rcu_force_quiescent_state);
| 
| This is -rt only, correct?

Yes, -rt only. And the only complaint I saw was from rcutorture.

Luis

Re: [PATCH] rcutorture: fix missing function at build time

[Paul E. McKenney]

On Mon, Mar 02, 2015 at 06:20:53PM -0300, Luis Claudio R. Goncalves wrote:
> On Mon, Mar 02, 2015 at 01:18:15PM -0800, Paul E. McKenney wrote:
> ...
> | > diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
> | > index a4e9e25..28a54f6 100644
> | > --- a/kernel/rcu/tree.c
> | > +++ b/kernel/rcu/tree.c
> | > @@ -378,6 +378,11 @@ void rcu_bh_force_quiescent_state(void)
> | >  	force_quiescent_state(&rcu_bh_state);
> | >  }
> | >  EXPORT_SYMBOL_GPL(rcu_bh_force_quiescent_state);
> | > +#else
> | > +void rcu_force_quiescent_state(void)
> | > +{
> | > +}
> | > +EXPORT_SYMBOL_GPL(rcu_force_quiescent_state);
> | 
> | This is -rt only, correct?
> 
> Yes, -rt only. And the only complaint I saw was from rcutorture.

Agreed, nothing other than rcutorture should use these.  Just thinking
out loud about what (if anything) should happen in mainline.

							Thanx, Paul

Re: [PATCH] rcutorture: fix missing function at build time

[Sebastian Andrzej Siewior]

* Luis Claudio R. Goncalves | 2015-03-02 17:15:31 [-0300]:

>Hello,
>
>This is a minor issue, but as I seem to have woken up Paul at 4AM with the
>many beeps from IRC I would feel bad if I did not send this patch to the
>list. Actually, as that patch has been sitting on my computer for a few
>days now, i already feel bad :)

Thanks. I folded this into
rcu-merge-rcu-bh-into-rcu-preempt-for-rt.patch since it is v3.18 only.

Sebastian