[PATCH] rcu: Remove unused variable

[PATCH] rcu: Remove unused variable

[Philippe Mazenauer]

Variable 'rdp' is set but not used in synchronize_rcu_expidited(). The
macro per_cpu_ptr() used to set the value of 'rdp' has no side effect.

../kernel/rcu/tree_exp.h:768:19: warning: variable ‘rdp’ set but not used [-Wunused-but-set-variable]
   struct rcu_data *rdp;
                    ^~~

Signed-off-by: Philippe Mazenauer <philippe.mazenauer@outlook.de>
---
 kernel/rcu/tree_exp.h | 2 --
 1 file changed, 2 deletions(-)

diff --git a/kernel/rcu/tree_exp.h b/kernel/rcu/tree_exp.h
index 9c990df880d1..41f56b6065c6 100644
--- a/kernel/rcu/tree_exp.h
+++ b/kernel/rcu/tree_exp.h
@@ -765,7 +765,6 @@ static int rcu_print_task_exp_stall(struct rcu_node *rnp)
  */
 void synchronize_rcu_expedited(void)
 {
-	struct rcu_data *rdp;
 	struct rcu_exp_work rew;
 	struct rcu_node *rnp;
 	unsigned long s;
@@ -802,7 +801,6 @@ void synchronize_rcu_expedited(void)
 	}
 
 	/* Wait for expedited grace period to complete. */
-	rdp = per_cpu_ptr(&rcu_data, raw_smp_processor_id());
 	rnp = rcu_get_root();
 	wait_event(rnp->exp_wq[rcu_seq_ctr(s) & 0x3],
 		   sync_exp_work_done(s));
-- 
2.17.1

Re: [PATCH] rcu: Remove unused variable

[Lee Jones]

On Fri, 17 May 2019, Philippe Mazenauer wrote:

> Variable 'rdp' is set but not used in synchronize_rcu_expidited(). The
> macro per_cpu_ptr() used to set the value of 'rdp' has no side effect.
> 
> ../kernel/rcu/tree_exp.h:768:19: warning: variable ‘rdp’ set but not used [-Wunused-but-set-variable]
>    struct rcu_data *rdp;
>                     ^~~
> 
> Signed-off-by: Philippe Mazenauer <philippe.mazenauer@outlook.de>
> ---
>  kernel/rcu/tree_exp.h | 2 --
>  1 file changed, 2 deletions(-)

Looks reasonable:

Acked-by: Lee Jones <lee.jones@linaro.org>

-- 
Lee Jones [李琼斯]
Linaro Services Technical Lead
Linaro.org │ Open source software for ARM SoCs
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Re: [PATCH] rcu: Remove unused variable

[Paul E. McKenney]

On Fri, May 17, 2019 at 11:51:11AM +0100, Lee Jones wrote:
> On Fri, 17 May 2019, Philippe Mazenauer wrote:
> 
> > Variable 'rdp' is set but not used in synchronize_rcu_expidited(). The
> > macro per_cpu_ptr() used to set the value of 'rdp' has no side effect.
> > 
> > ../kernel/rcu/tree_exp.h:768:19: warning: variable ‘rdp’ set but not used [-Wunused-but-set-variable]
> >    struct rcu_data *rdp;
> >                     ^~~
> > 
> > Signed-off-by: Philippe Mazenauer <philippe.mazenauer@outlook.de>
> > ---
> >  kernel/rcu/tree_exp.h | 2 --
> >  1 file changed, 2 deletions(-)
> 
> Looks reasonable:
> 
> Acked-by: Lee Jones <lee.jones@linaro.org>

Good eyes!

However, Jiang Biao beat you to it.  Please see commmit a18e1552af94
("rcu: Remove unused rdp local from synchronize_rcu_expedited()") in -rcu:
git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git branch
"dev".

							Thanx, Paul