From: Jesse Gross <jesse@nicira.com>
Date: Thu, 29 Jul 2010 22:59:31 +0000 (-0700)
Subject: vport: Make dp_port->vport always valid.
X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=cc98976af50fec5643a372aa9c7a4c4e565e939e;p=openvswitch

vport: Make dp_port->vport always valid.

When we detached a vport we would assign NULL to dp_port->vport
before calling synchronize_rcu().  However, since vports have a
longer lifetime than dp_ports there were no checks before
dereferencing dp_port->vport.  This changes the behavior to
match the assumption by not assigning NULL during detach.  This
avoids a potential NULL pointer dereference in do_output() among
other places.
---

diff --git a/datapath/datapath.c b/datapath/datapath.c
index 73f73480..d0db5507 100644
--- a/datapath/datapath.c
+++ b/datapath/datapath.c
@@ -377,6 +377,7 @@ static int new_dp_port(struct datapath *dp, struct odp_port *odp_port, int port_
 
 	p->port_no = port_no;
 	p->dp = dp;
+	p->vport = vport;
 	atomic_set(&p->sflow_pool, 0);
 
 	err = vport_attach(vport, p);
diff --git a/datapath/vport.c b/datapath/vport.c
index 712c26e5..24385901 100644
--- a/datapath/vport.c
+++ b/datapath/vport.c
@@ -798,9 +798,6 @@ int vport_attach(struct vport *vport, struct dp_port *dp_port)
 {
 	ASSERT_RTNL();
 
-	if (dp_port->vport)
-		return -EBUSY;
-
 	if (vport_get_dp_port(vport))
 		return -EBUSY;
 
@@ -812,7 +809,6 @@ int vport_attach(struct vport *vport, struct dp_port *dp_port)
 			return err;
 	}
 
-	dp_port->vport = vport;
 	rcu_assign_pointer(vport->dp_port, dp_port);
 
 	return 0;
@@ -836,7 +832,6 @@ int vport_detach(struct vport *vport)
 	if (!dp_port)
 		return -EINVAL;
 
-	dp_port->vport = NULL;
 	rcu_assign_pointer(vport->dp_port, NULL);
 
 	if (vport->ops->detach)