[ovs-dev] [refactor get_dp() V2] datapath: Refactor get_dp() function into multiple access APIs

Andy Zhou azhou at nicira.com
Mon Jul 21 20:39:52 UTC 2014


o  get_dp_rcu()      requires its caller to hold rcu lock.
o  get_dp()          requires its caller to hold either ovs lock or
                     rcu lock.
Signed-off-by: Andy Zhou <azhou at nicira.com>

---
v1->v2:   Reduce APIs from 4 to 2.
---
 datapath/datapath.c | 27 +++++++++++++++++++--------
 1 file changed, 19 insertions(+), 8 deletions(-)

diff --git a/datapath/datapath.c b/datapath/datapath.c
index 065356f..ba65947 100644
--- a/datapath/datapath.c
+++ b/datapath/datapath.c
@@ -140,19 +140,30 @@ static int queue_gso_packets(struct datapath *dp, struct sk_buff *,
 static int queue_userspace_packet(struct datapath *dp, struct sk_buff *,
 				  const struct dp_upcall_info *);
 
-/* Must be called with rcu_read_lock or ovs_mutex. */
-static struct datapath *get_dp(struct net *net, int dp_ifindex)
+/* Must be called with rcu_read_lock. */
+static struct datapath *get_dp_rcu(struct net *net, int dp_ifindex)
 {
+	struct net_device *dev = dev_get_by_index_rcu(net, dp_ifindex);
 	struct datapath *dp = NULL;
-	struct net_device *dev;
 
-	rcu_read_lock();
-	dev = dev_get_by_index_rcu(net, dp_ifindex);
 	if (dev) {
 		struct vport *vport = ovs_internal_dev_get_vport(dev);
 		if (vport)
 			dp = vport->dp;
 	}
+
+	return dp;
+}
+
+/* The caller must hold either ovs_mutex or rcu_read_lock to keep the
+ * returned dp pointer valid. */
+static inline struct datapath *get_dp(struct net *net, int dp_ifindex)
+{
+	struct datapath *dp;
+
+	WARN_ON_ONCE(!rcu_read_lock_held() && !lockdep_ovsl_is_held());
+	rcu_read_lock();
+	dp = get_dp_rcu(net, dp_ifindex);
 	rcu_read_unlock();
 
 	return dp;
@@ -595,7 +606,7 @@ static int ovs_packet_cmd_execute(struct sk_buff *skb, struct genl_info *info)
 	packet->mark = flow->key.phy.skb_mark;
 
 	rcu_read_lock();
-	dp = get_dp(sock_net(skb->sk), ovs_header->dp_ifindex);
+	dp = get_dp_rcu(sock_net(skb->sk), ovs_header->dp_ifindex);
 	err = -ENODEV;
 	if (!dp)
 		goto err_unlock;
@@ -1252,7 +1263,7 @@ static int ovs_flow_cmd_dump(struct sk_buff *skb, struct netlink_callback *cb)
 	struct datapath *dp;
 
 	rcu_read_lock();
-	dp = get_dp(sock_net(skb->sk), ovs_header->dp_ifindex);
+	dp = get_dp_rcu(sock_net(skb->sk), ovs_header->dp_ifindex);
 	if (!dp) {
 		rcu_read_unlock();
 		return -ENODEV;
@@ -2019,7 +2030,7 @@ static int ovs_vport_cmd_dump(struct sk_buff *skb, struct netlink_callback *cb)
 	int i, j = 0;
 
 	rcu_read_lock();
-	dp = get_dp(sock_net(skb->sk), ovs_header->dp_ifindex);
+	dp = get_dp_rcu(sock_net(skb->sk), ovs_header->dp_ifindex);
 	if (!dp) {
 		rcu_read_unlock();
 		return -ENODEV;
-- 
1.9.1




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