bonding: allow user-controlled output slave selection

v2: changed bonding module version, modified to apply on top of changes
from previous patch in series, and updated documentation to elaborate on
multiqueue awareness that now exists in bonding driver.

This patch give the user the ability to control the output slave for
round-robin and active-backup bonding.  Similar functionality was
discussed in the past, but Jay Vosburgh indicated he would rather see a
feature like this added to existing modes rather than creating a
completely new mode.  Jay's thoughts as well as Neil's input surrounding
some of the issues with the first implementation pushed us toward a
design that relied on the queue_mapping rather than skb marks.
Round-robin and active-backup modes were chosen as the first users of
this slave selection as they seemed like the most logical choices when
considering a multi-switch environment.

Round-robin mode works without any modification, but active-backup does
require inclusion of the first patch in this series and setting
the 'all_slaves_active' flag.  This will allow reception of unicast traffic on
any of the backup interfaces.

This was tested with IPv4-based filters as well as VLAN-based filters
with good results.

More information as well as a configuration example is available in the
patch to Documentation/networking/bonding.txt.

Signed-off-by: Andy Gospodarek <andy@greyhouse.net>
Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 72 insertions, 3 deletions

diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index f22f6bf43858..1b19276cff12 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -90,6 +90,7 @@
 #define BOND_LINK_ARP_INTERV	0
 
 static int max_bonds	= BOND_DEFAULT_MAX_BONDS;
+static int tx_queues	= BOND_DEFAULT_TX_QUEUES;
 static int num_grat_arp = 1;
 static int num_unsol_na = 1;
 static int miimon	= BOND_LINK_MON_INTERV;
@@ -111,6 +112,8 @@ static struct bond_params bonding_defaults;
 
 module_param(max_bonds, int, 0);
 MODULE_PARM_DESC(max_bonds, "Max number of bonded devices");
+module_param(tx_queues, int, 0);
+MODULE_PARM_DESC(tx_queues, "Max number of transmit queues (default = 16)");
 module_param(num_grat_arp, int, 0644);
 MODULE_PARM_DESC(num_grat_arp, "Number of gratuitous ARP packets to send on failover event");
 module_param(num_unsol_na, int, 0644);
@@ -1540,6 +1543,12 @@ int bond_enslave(struct net_device *bond_dev, struct net_device *slave_dev)
 		goto err_undo_flags;
 	}
 
+	/*
+	 * Set the new_slave's queue_id to be zero.  Queue ID mapping
+	 * is set via sysfs or module option if desired.
+	 */
+	new_slave->queue_id = 0;
+
 	/* Save slave's original mtu and then set it to match the bond */
 	new_slave->original_mtu = slave_dev->mtu;
 	res = dev_set_mtu(slave_dev, bond->dev->mtu);
@@ -3285,6 +3294,7 @@ static void bond_info_show_slave(struct seq_file *seq,
 		else
 			seq_puts(seq, "Aggregator ID: N/A\n");
 	}
+	seq_printf(seq, "Slave queue ID: %d\n", slave->queue_id);
 }
 
 static int bond_info_seq_show(struct seq_file *seq, void *v)
@@ -4421,9 +4431,59 @@ static void bond_set_xmit_hash_policy(struct bonding *bond)
 	}
 }
 
+/*
+ * Lookup the slave that corresponds to a qid
+ */
+static inline int bond_slave_override(struct bonding *bond,
+				      struct sk_buff *skb)
+{
+	int i, res = 1;
+	struct slave *slave = NULL;
+	struct slave *check_slave;
+
+	read_lock(&bond->lock);
+
+	if (!BOND_IS_OK(bond) || !skb->queue_mapping)
+		goto out;
+
+	/* Find out if any slaves have the same mapping as this skb. */
+	bond_for_each_slave(bond, check_slave, i) {
+		if (check_slave->queue_id == skb->queue_mapping) {
+			slave = check_slave;
+			break;
+		}
+	}
+
+	/* If the slave isn't UP, use default transmit policy. */
+	if (slave && slave->queue_id && IS_UP(slave->dev) &&
+	    (slave->link == BOND_LINK_UP)) {
+		res = bond_dev_queue_xmit(bond, skb, slave->dev);
+	}
+
+out:
+	read_unlock(&bond->lock);
+	return res;
+}
+
+static u16 bond_select_queue(struct net_device *dev, struct sk_buff *skb)
+{
+	/*
+	 * This helper function exists to help dev_pick_tx get the correct
+	 * destination queue.  Using a helper function skips the a call to
+	 * skb_tx_hash and will put the skbs in the queue we expect on their
+	 * way down to the bonding driver.
+	 */
+	return skb->queue_mapping;
+}
+
 static netdev_tx_t bond_start_xmit(struct sk_buff *skb, struct net_device *dev)
 {
-	const struct bonding *bond = netdev_priv(dev);
+	struct bonding *bond = netdev_priv(dev);
+
+	if (TX_QUEUE_OVERRIDE(bond->params.mode)) {
+		if (!bond_slave_override(bond, skb))
+			return NETDEV_TX_OK;
+	}
 
 	switch (bond->params.mode) {
 	case BOND_MODE_ROUNDROBIN:
@@ -4508,6 +4568,7 @@ static const struct net_device_ops bond_netdev_ops = {
 	.ndo_open		= bond_open,
 	.ndo_stop		= bond_close,
 	.ndo_start_xmit		= bond_start_xmit,
+	.ndo_select_queue	= bond_select_queue,
 	.ndo_get_stats		= bond_get_stats,
 	.ndo_do_ioctl		= bond_do_ioctl,
 	.ndo_set_multicast_list	= bond_set_multicast_list,
@@ -4776,6 +4837,13 @@ static int bond_check_params(struct bond_params *params)
 		}
 	}
 
+	if (tx_queues < 1 || tx_queues > 255) {
+		pr_warning("Warning: tx_queues (%d) should be between "
+			   "1 and 255, resetting to %d\n",
+			   tx_queues, BOND_DEFAULT_TX_QUEUES);
+		tx_queues = BOND_DEFAULT_TX_QUEUES;
+	}
+
 	if ((all_slaves_active != 0) && (all_slaves_active != 1)) {
 		pr_warning("Warning: all_slaves_active module parameter (%d), "
 			   "not of valid value (0/1), so it was set to "
@@ -4953,6 +5021,7 @@ static int bond_check_params(struct bond_params *params)
 	params->primary[0] = 0;
 	params->primary_reselect = primary_reselect_value;
 	params->fail_over_mac = fail_over_mac_value;
+	params->tx_queues = tx_queues;
 	params->all_slaves_active = all_slaves_active;
 
 	if (primary) {
@@ -5040,8 +5109,8 @@ int bond_create(struct net *net, const char *name)
 
 	rtnl_lock();
 
-	bond_dev = alloc_netdev(sizeof(struct bonding), name ? name : "",
-				bond_setup);
+	bond_dev = alloc_netdev_mq(sizeof(struct bonding), name ? name : "",
+				bond_setup, tx_queues);
 	if (!bond_dev) {
 		pr_err("%s: eek! can't alloc netdev!\n", name);
 		rtnl_unlock();