From: Ben Pfaff <blp@nicira.com>
Date: Thu, 7 May 2009 00:35:40 +0000 (-0700)
Subject: datapath: Call rcu_barrier() before unloading module.
X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=35cc2980d9393c16c69dfe5a3f9faddb77eb6811;p=openvswitch

datapath: Call rcu_barrier() before unloading module.

According to article "RCU and Unloadable Modules" available at lwn.net,
a module that uses RCU callbacks should call rcu_barrier() before
unloading, because synchronize_rcu() does not ensure that all RCU callbacks
have actually completed, only that a grace period has elapsed.
---

diff --git a/datapath/datapath.c b/datapath/datapath.c
index 252e3e00..d3dd6909 100644
--- a/datapath/datapath.c
+++ b/datapath/datapath.c
@@ -1648,6 +1648,7 @@ error:
 
 static void dp_cleanup(void)
 {
+	rcu_barrier();
 	unregister_chrdev(major, "openvswitch");
 	unregister_netdevice_notifier(&dp_device_notifier);
 	flow_exit();