[PATCH net 3/4] openvswitch: Fix race.

[Jesse Gross <jesse-l0M0P4e3n4LQT0dZR+AlfA@public.gmane.org>]

From: Jarno Rajahalme <jrajahalme-l0M0P4e3n4LQT0dZR+AlfA@public.gmane.org>

ovs_vport_cmd_dump() did rcu_read_lock() only after getting the
datapath, which could have been deleted in between.  Resolved by
taking rcu_read_lock() before the get_dp() call.

Signed-off-by: Jarno Rajahalme <jrajahalme-l0M0P4e3n4LQT0dZR+AlfA@public.gmane.org>
Signed-off-by: Pravin B Shelar <pshelar-l0M0P4e3n4LQT0dZR+AlfA@public.gmane.org>
---
 net/openvswitch/datapath.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/net/openvswitch/datapath.c b/net/openvswitch/datapath.c
index e42340d..8601b32 100644
--- a/net/openvswitch/datapath.c
+++ b/net/openvswitch/datapath.c
@@ -1762,11 +1762,12 @@ static int ovs_vport_cmd_dump(struct sk_buff *skb, struct netlink_callback *cb)
 	int bucket = cb->args[0], skip = cb->args[1];
 	int i, j = 0;
 
+	rcu_read_lock();
 	dp = get_dp(sock_net(skb->sk), ovs_header->dp_ifindex);
-	if (!dp)
+	if (!dp) {
+		rcu_read_unlock();
 		return -ENODEV;
-
-	rcu_read_lock();
+	}
 	for (i = bucket; i < DP_VPORT_HASH_BUCKETS; i++) {
 		struct vport *vport;
 
-- 
1.8.3.2