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, 116 insertions, 0 deletions

diff --git a/drivers/net/bonding/bond_sysfs.c b/drivers/net/bonding/bond_sysfs.c
index 066311a5e084..f9a034361a8e 100644
--- a/drivers/net/bonding/bond_sysfs.c
+++ b/drivers/net/bonding/bond_sysfs.c
@@ -1412,6 +1412,121 @@ static ssize_t bonding_show_ad_partner_mac(struct device *d,
 static DEVICE_ATTR(ad_partner_mac, S_IRUGO, bonding_show_ad_partner_mac, NULL);
 
 /*
+ * Show the queue_ids of the slaves in the current bond.
+ */
+static ssize_t bonding_show_queue_id(struct device *d,
+				     struct device_attribute *attr,
+				     char *buf)
+{
+	struct slave *slave;
+	int i, res = 0;
+	struct bonding *bond = to_bond(d);
+
+	if (!rtnl_trylock())
+		return restart_syscall();
+
+	read_lock(&bond->lock);
+	bond_for_each_slave(bond, slave, i) {
+		if (res > (PAGE_SIZE - 6)) {
+			/* not enough space for another interface name */
+			if ((PAGE_SIZE - res) > 10)
+				res = PAGE_SIZE - 10;
+			res += sprintf(buf + res, "++more++ ");
+			break;
+		}
+		res += sprintf(buf + res, "%s:%d ",
+			       slave->dev->name, slave->queue_id);
+	}
+	read_unlock(&bond->lock);
+	if (res)
+		buf[res-1] = '\n'; /* eat the leftover space */
+	rtnl_unlock();
+	return res;
+}
+
+/*
+ * Set the queue_ids of the  slaves in the current bond.  The bond
+ * interface must be enslaved for this to work.
+ */
+static ssize_t bonding_store_queue_id(struct device *d,
+				      struct device_attribute *attr,
+				      const char *buffer, size_t count)
+{
+	struct slave *slave, *update_slave;
+	struct bonding *bond = to_bond(d);
+	u16 qid;
+	int i, ret = count;
+	char *delim;
+	struct net_device *sdev = NULL;
+
+	if (!rtnl_trylock())
+		return restart_syscall();
+
+	/* delim will point to queue id if successful */
+	delim = strchr(buffer, ':');
+	if (!delim)
+		goto err_no_cmd;
+
+	/*
+	 * Terminate string that points to device name and bump it
+	 * up one, so we can read the queue id there.
+	 */
+	*delim = '\0';
+	if (sscanf(++delim, "%hd\n", &qid) != 1)
+		goto err_no_cmd;
+
+	/* Check buffer length, valid ifname and queue id */
+	if (strlen(buffer) > IFNAMSIZ ||
+	    !dev_valid_name(buffer) ||
+	    qid > bond->params.tx_queues)
+		goto err_no_cmd;
+
+	/* Get the pointer to that interface if it exists */
+	sdev = __dev_get_by_name(dev_net(bond->dev), buffer);
+	if (!sdev)
+		goto err_no_cmd;
+
+	read_lock(&bond->lock);
+
+	/* Search for thes slave and check for duplicate qids */
+	update_slave = NULL;
+	bond_for_each_slave(bond, slave, i) {
+		if (sdev == slave->dev)
+			/*
+			 * We don't need to check the matching
+			 * slave for dups, since we're overwriting it
+			 */
+			update_slave = slave;
+		else if (qid && qid == slave->queue_id) {
+			goto err_no_cmd_unlock;
+		}
+	}
+
+	if (!update_slave)
+		goto err_no_cmd_unlock;
+
+	/* Actually set the qids for the slave */
+	update_slave->queue_id = qid;
+
+	read_unlock(&bond->lock);
+out:
+	rtnl_unlock();
+	return ret;
+
+err_no_cmd_unlock:
+	read_unlock(&bond->lock);
+err_no_cmd:
+	pr_info("invalid input for queue_id set for %s.\n",
+		bond->dev->name);
+	ret = -EPERM;
+	goto out;
+}
+
+static DEVICE_ATTR(queue_id, S_IRUGO | S_IWUSR, bonding_show_queue_id,
+		   bonding_store_queue_id);
+
+
+/*
  * Show and set the all_slaves_active flag.
  */
 static ssize_t bonding_show_slaves_active(struct device *d,
@@ -1489,6 +1604,7 @@ static struct attribute *per_bond_attrs[] = {
 	&dev_attr_ad_actor_key.attr,
 	&dev_attr_ad_partner_key.attr,
 	&dev_attr_ad_partner_mac.attr,
+	&dev_attr_queue_id.attr,
 	&dev_attr_all_slaves_active.attr,
 	NULL,
 };