4 files changed, 64 insertions, 4 deletions
diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h
index c0cc7ae41106..f92443561d36 100644
--- a/kernel/rcu/tasks.h
+++ b/kernel/rcu/tasks.h
@@ -316,7 +316,8 @@ static void call_rcu_tasks_generic_timer(struct timer_list *tlp)
 	unsigned long flags;
 	bool needwake = false;
 	struct rcu_tasks *rtp;
-	struct rcu_tasks_percpu *rtpcp = from_timer(rtpcp, tlp, lazy_timer);
+	struct rcu_tasks_percpu *rtpcp = timer_container_of(rtpcp, tlp,
+						            lazy_timer);
 
 	rtp = rtpcp->rtpp;
 	raw_spin_lock_irqsave_rcu_node(rtpcp, flags);
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index e8a4b720d7d2..14d4499c6fc3 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -3072,6 +3072,10 @@ __call_rcu_common(struct rcu_head *head, rcu_callback_t func, bool lazy_in)
 	/* Misaligned rcu_head! */
 	WARN_ON_ONCE((unsigned long)head & (sizeof(void *) - 1));
 
+	/* Avoid NULL dereference if callback is NULL. */
+	if (WARN_ON_ONCE(!func))
+		return;
+
 	if (debug_rcu_head_queue(head)) {
 		/*
 		 * Probable double call_rcu(), so leak the callback.
diff --git a/kernel/rcu/tree_nocb.h b/kernel/rcu/tree_nocb.h
index 1596812f7f12..b473ff056f49 100644
--- a/kernel/rcu/tree_nocb.h
+++ b/kernel/rcu/tree_nocb.h
@@ -985,7 +985,7 @@ static bool do_nocb_deferred_wakeup_common(struct rcu_data *rdp_gp,
 static void do_nocb_deferred_wakeup_timer(struct timer_list *t)
 {
 	unsigned long flags;
-	struct rcu_data *rdp = from_timer(rdp, t, nocb_timer);
+	struct rcu_data *rdp = timer_container_of(rdp, t, nocb_timer);
 
 	WARN_ON_ONCE(rdp->nocb_gp_rdp != rdp);
 	trace_rcu_nocb_wake(rcu_state.name, rdp->cpu, TPS("Timer"));
diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h
index 56b21219442b..69482c2f0771 100644
--- a/kernel/rcu/tree_stall.h
+++ b/kernel/rcu/tree_stall.h
@@ -17,8 +17,59 @@
 // Controlling CPU stall warnings, including delay calculation.
 
 /* panic() on RCU Stall sysctl. */
-int sysctl_panic_on_rcu_stall __read_mostly;
-int sysctl_max_rcu_stall_to_panic __read_mostly;
+static int sysctl_panic_on_rcu_stall __read_mostly;
+static int sysctl_max_rcu_stall_to_panic __read_mostly;
+
+static const struct ctl_table rcu_stall_sysctl_table[] = {
+	{
+		.procname	= "panic_on_rcu_stall",
+		.data		= &sysctl_panic_on_rcu_stall,
+		.maxlen		= sizeof(sysctl_panic_on_rcu_stall),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_minmax,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_ONE,
+	},
+	{
+		.procname	= "max_rcu_stall_to_panic",
+		.data		= &sysctl_max_rcu_stall_to_panic,
+		.maxlen		= sizeof(sysctl_max_rcu_stall_to_panic),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_minmax,
+		.extra1		= SYSCTL_ONE,
+		.extra2		= SYSCTL_INT_MAX,
+	},
+};
+
+static int __init init_rcu_stall_sysctl(void)
+{
+	register_sysctl_init("kernel", rcu_stall_sysctl_table);
+	return 0;
+}
+
+subsys_initcall(init_rcu_stall_sysctl);
+
+#ifdef CONFIG_SYSFS
+
+static unsigned int rcu_stall_count;
+
+static ssize_t rcu_stall_count_show(struct kobject *kobj, struct kobj_attribute *attr,
+				    char *page)
+{
+	return sysfs_emit(page, "%u\n", rcu_stall_count);
+}
+
+static struct kobj_attribute rcu_stall_count_attr = __ATTR_RO(rcu_stall_count);
+
+static __init int kernel_rcu_stall_sysfs_init(void)
+{
+	sysfs_add_file_to_group(kernel_kobj, &rcu_stall_count_attr.attr, NULL);
+	return 0;
+}
+
+late_initcall(kernel_rcu_stall_sysfs_init);
+
+#endif // CONFIG_SYSFS
 
 #ifdef CONFIG_PROVE_RCU
 #define RCU_STALL_DELAY_DELTA		(5 * HZ)
@@ -784,6 +835,10 @@ static void check_cpu_stall(struct rcu_data *rdp)
 		if (kvm_check_and_clear_guest_paused())
 			return;
 
+#ifdef CONFIG_SYSFS
+		++rcu_stall_count;
+#endif
+
 		rcu_stall_notifier_call_chain(RCU_STALL_NOTIFY_NORM, (void *)j - gps);
 		if (READ_ONCE(csd_lock_suppress_rcu_stall) && csd_lock_is_stuck()) {
 			pr_err("INFO: %s detected stall, but suppressed full report due to a stuck CSD-lock.\n", rcu_state.name);