commit 58af207f726b5250b3da3505cdb8174ef9133807
Author: Ryota Ozaki <ozaki-r@iij.ad.jp>
Date:   Thu Jul 7 19:08:31 2016 +0900

    workaround for workqueue of ipflow slowtimo

diff --git a/sys/netinet/ip_flow.c b/sys/netinet/ip_flow.c
index 00602af..791e83b 100644
--- a/sys/netinet/ip_flow.c
+++ b/sys/netinet/ip_flow.c
@@ -430,6 +430,8 @@ ipflow_reap(bool just_one)
 	return NULL;
 }
 
+static bool ipflow_work_enqueued = false;
+
 static void
 ipflow_slowtimo_work(struct work *wk, void *arg)
 {
@@ -456,6 +458,7 @@ ipflow_slowtimo_work(struct work *wk, void *arg)
 			ipf->ipf_uses = 0;
 		}
 	}
+	ipflow_work_enqueued = false;
 	KERNEL_UNLOCK_ONE(NULL);
 	mutex_exit(&ipflow_lock);
 	mutex_exit(softnet_lock);
@@ -465,6 +468,15 @@ void
 ipflow_slowtimo(void)
 {
 
+	/* Avoid enqueuing another work when one is already enqueued */
+	mutex_enter(&ipflow_lock);
+	if (ipflow_work_enqueued) {
+		mutex_exit(&ipflow_lock);
+		return;
+	}
+	ipflow_work_enqueued = true;
+	mutex_exit(&ipflow_lock);
+
 	workqueue_enqueue(ipflow_slowtimo_wq, &ipflow_slowtimo_wk, NULL);
 }
 
diff --git a/sys/netinet6/ip6_flow.c b/sys/netinet6/ip6_flow.c
index 23fddde..0a588f6 100644
--- a/sys/netinet6/ip6_flow.c
+++ b/sys/netinet6/ip6_flow.c
@@ -466,6 +466,8 @@ ip6flow_reap(int just_one)
 	return ip6f;
 }
 
+static bool ip6flow_work_enqueued = false;
+
 void
 ip6flow_slowtimo_work(struct work *wk, void *arg)
 {
@@ -488,6 +490,7 @@ ip6flow_slowtimo_work(struct work *wk, void *arg)
 			ip6f->ip6f_forwarded = 0;
 		}
 	}
+	ip6flow_work_enqueued = false;
 
 	KERNEL_UNLOCK_ONE(NULL);
 	mutex_exit(&ip6flow_lock);
@@ -498,6 +501,15 @@ void
 ip6flow_slowtimo(void)
 {
 
+	/* Avoid enqueuing another work when one is already enqueued */
+	mutex_enter(&ip6flow_lock);
+	if (ip6flow_work_enqueued) {
+		mutex_exit(&ip6flow_lock);
+		return;
+	}
+	ip6flow_work_enqueued = true;
+	mutex_exit(&ip6flow_lock);
+
 	workqueue_enqueue(ip6flow_slowtimo_wq, &ip6flow_slowtimo_wk, NULL);
 }