datapath: Minimize ovs_flow_cmd_del critical section.

ovs_flow_cmd_del() now allocates reply (if needed) after the flow has
already been removed from the flow table.  If the reply allocation
fails, a netlink error is signaled with netlink_set_err(), as is
already done in ovs_flow_cmd_new_or_set() in the similar situation.

Signed-off-by: Jarno Rajahalme <jrajahalme@nicira.com>
Signed-off-by: Pravin B Shelar <pshelar@nicira.com>

diff --git a/datapath/datapath.c b/datapath/datapath.c
index 6f818f4..aa0ce9e 100644 (file)
--- a/datapath/datapath.c
+++ b/datapath/datapath.c
@@ -986,51 +986,54 @@ static int ovs_flow_cmd_del(struct sk_buff *skb, struct genl_info *info)
        struct sw_flow_match match;
        int err;
 
+       if (likely(a[OVS_FLOW_ATTR_KEY])) {
+               ovs_match_init(&match, &key, NULL);
+               err = ovs_nla_get_match(&match, a[OVS_FLOW_ATTR_KEY], NULL);
+               if (unlikely(err))
+                       return err;
+       }
+
        ovs_lock();
        dp = get_dp(sock_net(skb->sk), ovs_header->dp_ifindex);
-       if (!dp) {
+       if (unlikely(!dp)) {
                err = -ENODEV;
                goto unlock;
        }
-
-       if (!a[OVS_FLOW_ATTR_KEY]) {
+       if (unlikely(!a[OVS_FLOW_ATTR_KEY])) {
                err = ovs_flow_tbl_flush(&dp->table);
                goto unlock;
        }
-
-       ovs_match_init(&match, &key, NULL);
-       err = ovs_nla_get_match(&match, a[OVS_FLOW_ATTR_KEY], NULL);
-       if (err)
-               goto unlock;
-
        flow = ovs_flow_tbl_lookup(&dp->table, &key);
-       if (!flow || !ovs_flow_cmp_unmasked_key(flow, &match)) {
+       if (unlikely(!flow || !ovs_flow_cmp_unmasked_key(flow, &match))) {
                err = -ENOENT;
                goto unlock;
        }
 
-       reply = ovs_flow_cmd_alloc_info(ovsl_dereference(flow->sf_acts), info,
-                                       false);
-       if (IS_ERR(reply)) {
-               err = PTR_ERR(reply);
-               goto unlock;
-       }
-
        ovs_flow_tbl_remove(&dp->table, flow);
+       ovs_unlock();
 
-       if (reply) {
-               err = ovs_flow_cmd_fill_info(flow, ovs_header->dp_ifindex,
-                                            reply, info->snd_portid,
-                                            info->snd_seq, 0,
-                                            OVS_FLOW_CMD_DEL);
-               BUG_ON(err < 0);
+       reply = ovs_flow_cmd_alloc_info((const struct sw_flow_actions __force *)flow->sf_acts,
+                                       info, false);
+
+       if (likely(reply)) {
+               if (likely(!IS_ERR(reply))) {
+                       rcu_read_lock(); /* Keep RCU checker happy. */
+                       err = ovs_flow_cmd_fill_info(flow,
+                                                    ovs_header->dp_ifindex,
+                                                    reply, info->snd_portid,
+                                                    info->snd_seq, 0,
+                                                    OVS_FLOW_CMD_DEL);
+                       rcu_read_unlock();
+                       BUG_ON(err < 0);
+                       ovs_notify(reply, info, &ovs_dp_flow_multicast_group);
+               } else {
+                       netlink_set_err(sock_net(skb->sk)->genl_sock, 0,
+                                       ovs_dp_flow_multicast_group.id,
+                                       PTR_ERR(reply));
+               }
        }
 
        ovs_flow_free(flow, true);
-       ovs_unlock();
-
-       if (reply)
-               ovs_notify(reply, info, &ovs_dp_flow_multicast_group);
        return 0;
 unlock:
        ovs_unlock();