[ovs-dev] [PATCH v2 11/13] datapath: Remove memory allocations from ovs_flow_cmd_execute.

[Jarno Rajahalme]

Signed-off-by: Jarno Rajahalme <jrajahalme at nicira.com>
---
 datapath/datapath.c |   60 +++++++++++++++++++++++++++------------------------
 1 file changed, 32 insertions(+), 28 deletions(-)

diff --git a/datapath/datapath.c b/datapath/datapath.c
index a46ceb0..90fdc60 100644
--- a/datapath/datapath.c
+++ b/datapath/datapath.c
@@ -492,14 +492,24 @@ static int ovs_packet_cmd_execute(struct sk_buff *skb, struct genl_info *info)
 {
 	struct ovs_header *ovs_header = info->userhdr;
 	struct nlattr **a = info->attrs;
-	struct sw_flow_actions *acts;
 	struct sk_buff *packet;
-	struct sw_flow *flow;
 	struct datapath *dp;
 	struct ethhdr *eth;
+	struct sw_flow flow;
+	struct {
+		struct sw_flow_actions acts;
+		u64 buf[512 / sizeof (u64)];
+	} sw_acts;
+	struct sw_flow_actions *acts;
 	int len;
 	int err;
 
+	/* Start with actions in the stack with enough space for most cases. */
+	acts = &sw_acts.acts;
+	acts->actions_len = 0;
+	acts->alloc_size = sizeof(sw_acts);
+	acts->alloced = false;
+
 	err = -EINVAL;
 	if (!a[OVS_PACKET_ATTR_PACKET] || !a[OVS_PACKET_ATTR_KEY] ||
 	    !a[OVS_PACKET_ATTR_ACTIONS])
@@ -525,54 +535,48 @@ static int ovs_packet_cmd_execute(struct sk_buff *skb, struct genl_info *info)
 	else
 		packet->protocol = htons(ETH_P_802_2);
 
-	/* Build an sw_flow for sending this packet. */
-	flow = ovs_flow_alloc();
-	err = PTR_ERR(flow);
-	if (IS_ERR(flow))
-		goto err_kfree_skb;
-
-	err = ovs_flow_extract(packet, -1, &flow->key);
+	/* Build an sw_flow for sending this packet.
+	 * We do not initialize mask, nor stats as they are not used
+	 * by a flow that is not in the flow table. */
+	err = ovs_flow_extract(packet, -1, &flow.key);
 	if (err)
-		goto err_flow_free;
+		goto err_free;
 
-	err = ovs_nla_get_flow_metadata(flow, a[OVS_PACKET_ATTR_KEY]);
+	err = ovs_nla_get_flow_metadata(&flow, a[OVS_PACKET_ATTR_KEY]);
 	if (err)
-		goto err_flow_free;
-	acts = ovs_nla_alloc_flow_actions(nla_len(a[OVS_PACKET_ATTR_ACTIONS]));
-	err = PTR_ERR(acts);
-	if (IS_ERR(acts))
-		goto err_flow_free;
+		goto err_free;
 
 	err = ovs_nla_copy_actions(a[OVS_PACKET_ATTR_ACTIONS],
-				   &flow->key, 0, &acts);
-	rcu_assign_pointer(flow->sf_acts, acts);
+				   &flow.key, 0, &acts);
+	rcu_assign_pointer(flow.sf_acts, acts);
 	if (err)
-		goto err_flow_free;
+		goto err_free_acts;
 
-	OVS_CB(packet)->flow = flow;
-	OVS_CB(packet)->pkt_key = &flow->key;
-	packet->priority = flow->key.phy.priority;
-	packet->mark = flow->key.phy.skb_mark;
+	OVS_CB(packet)->flow = &flow;
+	OVS_CB(packet)->pkt_key = &flow.key;
+	packet->priority = flow.key.phy.priority;
+	packet->mark = flow.key.phy.skb_mark;
 
 	rcu_read_lock();
 	dp = get_dp(sock_net(skb->sk), ovs_header->dp_ifindex);
 	err = -ENODEV;
 	if (!dp)
 		goto err_unlock;
-
 	local_bh_disable();
 	err = ovs_execute_actions(dp, packet);
 	local_bh_enable();
 	rcu_read_unlock();
 
-	ovs_flow_free(flow, false);
+	/* Will free if actions were realloced. */
+	ovs_nla_free_flow_actions(acts, false);
+
 	return err;
 
 err_unlock:
 	rcu_read_unlock();
-err_flow_free:
-	ovs_flow_free(flow, false);
-err_kfree_skb:
+err_free_acts:
+	ovs_nla_free_flow_actions(acts, false);
+err_free:
 	kfree_skb(packet);
 err:
 	return err;
-- 
1.7.10.4