rcutorture: Check GP completion at stutter end

The rcu_torture_writer() function invokes stutter_wait() at the end of
each writer pass, which occasionally blocks for an extended time period
in order to ensure that RCU can handle intermittent loads.  But part of
handling a busy period is invoking all the callbacks before the end of
the idle period induced by stutter_wait().

This commit therefore adds a return value to stutter_wait() indicating
whether stutter_wait() actually waited.  In addition, this commit causes
rcu_torture_writer() to test this value and if set, checks that all the
elements of the rcu_tortures[] array have been freed up.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/kernel/torture.c b/kernel/torture.c
index 1ac24a826589..17d91f5fba2a 100644
--- a/kernel/torture.c
+++ b/kernel/torture.c
@@ -573,7 +573,7 @@ static int stutter;
  * Block until the stutter interval ends.  This must be called periodically
  * by all running kthreads that need to be subject to stuttering.
  */
-void stutter_wait(const char *title)
+bool stutter_wait(const char *title)
 {
 	int spt;
 
@@ -590,6 +590,7 @@ void stutter_wait(const char *title)
 		}
 		torture_shutdown_absorb(title);
 	}
+	return !!spt;
 }
 EXPORT_SYMBOL_GPL(stutter_wait);