openvswitch: 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>

1 files changed, 28 insertions, 25 deletions

diff --git a/net/openvswitch/datapath.c b/net/openvswitch/datapath.c
index 949fc7fadaf0..f28beda8426f 100644
--- a/net/openvswitch/datapath.c
+++ b/net/openvswitch/datapath.c
@@ -984,50 +984,53 @@ 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();        /*To 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(&dp_flow_genl_family, reply, info);
+                } else {
+                        netlink_set_err(sock_net(skb->sk)->genl_sock, 0, 0, PTR_ERR(reply));
+                }
         }
-        ovs_flow_free(flow, true);
-        ovs_unlock();
 
-        if (reply)
-                ovs_notify(&dp_flow_genl_family, reply, info);
+        ovs_flow_free(flow, true);
         return 0;
 unlock:
         ovs_unlock();