rcutorture: Check preemption for failing reader

This commit checks to see if the RCU reader has been preempted within
its read-side critical section for RCU flavors supporting this notion
(currently only preemptible RCU).  If such a preemption occurred, then
this is printed at the end of the "Failure/close-call rcutorture reader
segments" list at the end of the rcutorture run.

[ paulmck: Apply kernel test robot feedback. ]

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Frederic Weisbecker <frederic@kernel.org>
Tested-by: kernel test robot <oliver.sang@intel.com>
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>

1 files changed, 11 insertions, 0 deletions

diff --git a/include/linux/rcupdate_wait.h b/include/linux/rcupdate_wait.h
index 303ab9bee155..f9bed3d3f78d 100644
--- a/include/linux/rcupdate_wait.h
+++ b/include/linux/rcupdate_wait.h
@@ -65,4 +65,15 @@ static inline void cond_resched_rcu(void)
 #endif
 }
 
+// Has the current task blocked within its current RCU read-side
+// critical section?
+static inline bool has_rcu_reader_blocked(void)
+{
+#ifdef CONFIG_PREEMPT_RCU
+	return !list_empty(&current->rcu_node_entry);
+#else
+	return false;
+#endif
+}
+
 #endif /* _LINUX_SCHED_RCUPDATE_WAIT_H */