team: introduce random mode

As suggested by Eric Dumazet, allow user to select mode which chooses
TX port randomly. Functionality should be more of less similar to
round-robin mode with even lower overhead.
Signed-off-by: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/team/Kconfig

@@ -37,6 +37,18 @@ config NET_TEAM_MODE_ROUNDROBIN
 	  To compile this team mode as a module, choose M here: the module
 	  will be called team_mode_roundrobin.
 
+config NET_TEAM_MODE_RANDOM
+	tristate "Random mode support"
+	depends on NET_TEAM
+	---help---
+	  Basic mode where port used for transmitting packets is selected
+	  randomly.
+
+	  All added ports are setup to have team's device address.
+
+	  To compile this team mode as a module, choose M here: the module
+	  will be called team_mode_random.
+
 config NET_TEAM_MODE_ACTIVEBACKUP
 	tristate "Active-backup mode support"
 	depends on NET_TEAM

drivers/net/team/Makefile

@@ -5,5 +5,6 @@
 obj-$(CONFIG_NET_TEAM) += team.o
 obj-$(CONFIG_NET_TEAM_MODE_BROADCAST) += team_mode_broadcast.o
 obj-$(CONFIG_NET_TEAM_MODE_ROUNDROBIN) += team_mode_roundrobin.o
+obj-$(CONFIG_NET_TEAM_MODE_RANDOM) += team_mode_random.o
 obj-$(CONFIG_NET_TEAM_MODE_ACTIVEBACKUP) += team_mode_activebackup.o
 obj-$(CONFIG_NET_TEAM_MODE_LOADBALANCE) += team_mode_loadbalance.o

drivers/net/team/team_mode_random.c

+/*
+ * drivers/net/team/team_mode_random.c - Random mode for team
+ * Copyright (c) 2013 Jiri Pirko <jiri@resnulli.us>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#include <linux/kernel.h>
+#include <linux/types.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/skbuff.h>
+#include <linux/reciprocal_div.h>
+#include <linux/if_team.h>
+
+static u32 random_N(unsigned int N)
+{
+	return reciprocal_divide(random32(), N);
+}
+
+static bool rnd_transmit(struct team *team, struct sk_buff *skb)
+{
+	struct team_port *port;
+	int port_index;
+
+	port_index = random_N(team->en_port_count);
+	port = team_get_port_by_index_rcu(team, port_index);
+	port = team_get_first_port_txable_rcu(team, port);
+	if (unlikely(!port))
+		goto drop;
+	if (team_dev_queue_xmit(team, port, skb))
+		return false;
+	return true;
+
+drop:
+	dev_kfree_skb_any(skb);
+	return false;
+}
+
+static const struct team_mode_ops rnd_mode_ops = {
+	.transmit		= rnd_transmit,
+	.port_enter		= team_modeop_port_enter,
+	.port_change_dev_addr	= team_modeop_port_change_dev_addr,
+};
+
+static const struct team_mode rnd_mode = {
+	.kind		= "random",
+	.owner		= THIS_MODULE,
+	.ops		= &rnd_mode_ops,
+};
+
+static int __init rnd_init_module(void)
+{
+	return team_mode_register(&rnd_mode);
+}
+
+static void __exit rnd_cleanup_module(void)
+{
+	team_mode_unregister(&rnd_mode);
+}
+
+module_init(rnd_init_module);
+module_exit(rnd_cleanup_module);
+
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Jiri Pirko <jiri@resnulli.us>");
+MODULE_DESCRIPTION("Random mode for team");
+MODULE_ALIAS("team-mode-random");

drivers/net/team/team_mode_roundrobin.c

@@ -25,26 +25,6 @@ static struct rr_priv *rr_priv(struct team *team)
 	return (struct rr_priv *) &team->mode_priv;
 }
 
-static struct team_port *__get_first_port_up(struct team *team,
-					     struct team_port *port)
-{
-	struct team_port *cur;
-
-	if (team_port_txable(port))
-		return port;
-	cur = port;
-	list_for_each_entry_continue_rcu(cur, &team->port_list, list)
-		if (team_port_txable(port))
-			return cur;
-	list_for_each_entry_rcu(cur, &team->port_list, list) {
-		if (cur == port)
-			break;
-		if (team_port_txable(port))
-			return cur;
-	}
-	return NULL;
-}
-
 static bool rr_transmit(struct team *team, struct sk_buff *skb)
 {
 	struct team_port *port;
@@ -52,7 +32,7 @@ static bool rr_transmit(struct team *team, struct sk_buff *skb)
 
 	port_index = rr_priv(team)->sent_packets++ % team->en_port_count;
 	port = team_get_port_by_index_rcu(team, port_index);
-	port = __get_first_port_up(team, port);
+	port = team_get_first_port_txable_rcu(team, port);
 	if (unlikely(!port))
 		goto drop;
 	if (team_dev_queue_xmit(team, port, skb))

include/linux/if_team.h

@@ -240,6 +240,26 @@ static inline struct team_port *team_get_port_by_index_rcu(struct team *team,
 	return NULL;
 }
 
+static inline struct team_port *
+team_get_first_port_txable_rcu(struct team *team, struct team_port *port)
+{
+	struct team_port *cur;
+
+	if (likely(team_port_txable(port)))
+		return port;
+	cur = port;
+	list_for_each_entry_continue_rcu(cur, &team->port_list, list)
+		if (team_port_txable(port))
+			return cur;
+	list_for_each_entry_rcu(cur, &team->port_list, list) {
+		if (cur == port)
+			break;
+		if (team_port_txable(port))
+			return cur;
+	}
+	return NULL;
+}
+
 extern int team_options_register(struct team *team,
 				 const struct team_option *option,
 				 size_t option_count);