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>
diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index 9decce0..37ae5e1 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -1034,6 +1034,7 @@
"??? Writer stall state %d g%lu c%lu f%#x\n",
rcu_torture_writer_state,
gpnum, completed, flags);
+ show_rcu_gp_kthreads();
rcutorture_trace_dump();
}
rtcv_snap = rcu_torture_current_version;
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 3d15b5a..93e6438 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -280,6 +280,21 @@
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 @@
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 @@
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) ||
diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h
index 75dc3c3..c2fd1e7 100644
--- a/kernel/rcu/tree.h
+++ b/kernel/rcu/tree.h
@@ -406,7 +406,8 @@
unsigned long completed; /* # of last completed gp. */
struct task_struct *gp_kthread; /* Task for grace periods. */
wait_queue_head_t gp_wq; /* Where GP task waits. */
- int gp_flags; /* Commands for GP task. */
+ short gp_flags; /* Commands for GP task. */
+ short gp_state; /* GP kthread sleep state. */
/* End of fields guarded by root rcu_node's lock. */
@@ -469,6 +470,11 @@
#define RCU_GP_FLAG_INIT 0x1 /* Need grace-period initialization. */
#define RCU_GP_FLAG_FQS 0x2 /* Need grace-period quiescent-state forcing. */
+/* Values for rcu_state structure's gp_flags field. */
+#define RCU_GP_WAIT_INIT 0 /* Initial state. */
+#define RCU_GP_WAIT_GPS 1 /* Wait for grace-period start. */
+#define RCU_GP_WAIT_FQS 2 /* Wait for force-quiescent-state time. */
+
extern struct list_head rcu_struct_flavors;
/* Sequence through rcu_state structures for each RCU flavor. */