rcu/nocb: Print no-CBs diagnostics when rcutorture writer unduly delayed

This commit causes locking, sleeping, and callback state to be printed
for no-CBs CPUs when the rcutorture writer is delayed sufficiently for
rcutorture to complain.

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

1 files changed, 6 insertions, 1 deletions

diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h
index e4df86db8137..c612f306fe89 100644
--- a/kernel/rcu/tree.h
+++ b/kernel/rcu/tree.h
@@ -212,7 +212,11 @@ struct rcu_data {
         /* The following fields are used by GP kthread, hence own cacheline. */
         raw_spinlock_t nocb_gp_lock ____cacheline_internodealigned_in_smp;
         struct timer_list nocb_bypass_timer; /* Force nocb_bypass flush. */
-        bool nocb_gp_sleep;             /* Is the nocb GP thread asleep? */
+        u8 nocb_gp_sleep;               /* Is the nocb GP thread asleep? */
+        u8 nocb_gp_bypass;              /* Found a bypass on last scan? */
+        u8 nocb_gp_gp;                  /* GP to wait for on last scan? */
+        unsigned long nocb_gp_seq;      /*  If so, ->gp_seq to wait for. */
+        unsigned long nocb_gp_loops;    /* # passes through wait code. */
         struct swait_queue_head nocb_gp_wq; /* For nocb kthreads to sleep on. */
         bool nocb_cb_sleep;             /* Is the nocb CB thread asleep? */
         struct task_struct *nocb_cb_kthread;
@@ -438,6 +442,7 @@ static void do_nocb_deferred_wakeup(struct rcu_data *rdp);
 static void rcu_boot_init_nocb_percpu_data(struct rcu_data *rdp);
 static void rcu_spawn_cpu_nocb_kthread(int cpu);
 static void __init rcu_spawn_nocb_kthreads(void);
+static void show_rcu_nocb_state(struct rcu_data *rdp);
 static void rcu_nocb_lock(struct rcu_data *rdp);
 static void rcu_nocb_unlock(struct rcu_data *rdp);
 static void rcu_nocb_unlock_irqrestore(struct rcu_data *rdp,