rcutorture: Export RCU grace-period kthread wait state to rcutorture

This commit allows rcutorture to print additional state for the
RCU grace-period kthreads in cases where RCU seems reluctant to
start a new grace period.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>

1 files changed, 17 insertions, 0 deletions

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 3d15b5a82ae8..93e64381aa2a 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -280,6 +280,21 @@ void rcu_bh_force_quiescent_state(void)
 EXPORT_SYMBOL_GPL(rcu_bh_force_quiescent_state);
 
 /*
+ * Show the state of the grace-period kthreads.
+ */
+void show_rcu_gp_kthreads(void)
+{
+        struct rcu_state *rsp;
+
+        for_each_rcu_flavor(rsp) {
+                pr_info("%s: wait state: %d ->state: %#lx\n",
+                        rsp->name, rsp->gp_state, rsp->gp_kthread->state);
+                /* sched_show_task(rsp->gp_kthread); */
+        }
+}
+EXPORT_SYMBOL_GPL(show_rcu_gp_kthreads);
+
+/*
  * Record the number of times rcutorture tests have been initiated and
  * terminated.  This information allows the debugfs tracing stats to be
  * correlated to the rcutorture messages, even when the rcutorture module
@@ -1626,6 +1641,7 @@ static int __noreturn rcu_gp_kthread(void *arg)
                         trace_rcu_grace_period(rsp->name,
                                                ACCESS_ONCE(rsp->gpnum),
                                                TPS("reqwait"));
+                        rsp->gp_state = RCU_GP_WAIT_GPS;
                         wait_event_interruptible(rsp->gp_wq,
                                                  ACCESS_ONCE(rsp->gp_flags) &
                                                  RCU_GP_FLAG_INIT);
@@ -1653,6 +1669,7 @@ static int __noreturn rcu_gp_kthread(void *arg)
                         trace_rcu_grace_period(rsp->name,
                                                ACCESS_ONCE(rsp->gpnum),
                                                TPS("fqswait"));
+                        rsp->gp_state = RCU_GP_WAIT_FQS;
                         ret = wait_event_interruptible_timeout(rsp->gp_wq,
                                         ((gf = ACCESS_ONCE(rsp->gp_flags)) &
                                          RCU_GP_FLAG_FQS) ||