bonding: factor out slave id tx code and simplify xmit paths

I factored out the tx xmit code which relies on slave id in
bond_xmit_slave_id. It is global because later it can be used also in
3ad mode xmit. Unnecessary obvious comments are removed. Active-backup
mode is simplified because bond_dev_queue_xmit always consumes the skb.
bond_xmit_xor becomes one line because of bond_xmit_slave_id.
bond_for_each_slave_from is not used in bond_xmit_slave_id because later
when RCU is used we can avoid important race condition by using standard
rculist routines.

Signed-off-by: Nikolay Aleksandrov <nikolay@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index aa9da006fa68b17d0420496ca32a853f7846835d..5eee95c3b1726e2e968ee6ff0376ba312047060e 100644 (file)
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -3795,12 +3795,50 @@ unwind:
        return res;
 }
 
+/**
+ * bond_xmit_slave_id - transmit skb through slave with slave_id
+ * @bond: bonding device that is transmitting
+ * @skb: buffer to transmit
+ * @slave_id: slave id up to slave_cnt-1 through which to transmit
+ *
+ * This function tries to transmit through slave with slave_id but in case
+ * it fails, it tries to find the first available slave for transmission.
+ * The skb is consumed in all cases, thus the function is void.
+ */
+void bond_xmit_slave_id(struct bonding *bond, struct sk_buff *skb, int slave_id)
+{
+       struct slave *slave;
+       int i = slave_id;
+
+       /* Here we start from the slave with slave_id */
+       bond_for_each_slave(bond, slave) {
+               if (--i < 0) {
+                       if (slave_can_tx(slave)) {
+                               bond_dev_queue_xmit(bond, skb, slave->dev);
+                               return;
+                       }
+               }
+       }
+
+       /* Here we start from the first slave up to slave_id */
+       i = slave_id;
+       bond_for_each_slave(bond, slave) {
+               if (--i < 0)
+                       break;
+               if (slave_can_tx(slave)) {
+                       bond_dev_queue_xmit(bond, skb, slave->dev);
+                       return;
+               }
+       }
+       /* no slave that can tx has been found */
+       kfree_skb(skb);
+}
+
 static int bond_xmit_roundrobin(struct sk_buff *skb, struct net_device *bond_dev)
 {
        struct bonding *bond = netdev_priv(bond_dev);
-       struct slave *slave, *start_at;
-       int i, slave_no, res = 1;
        struct iphdr *iph = ip_hdr(skb);
+       struct slave *slave;
 
        /*
         * Start with the curr_active_slave that joined the bond as the
@@ -3809,46 +3847,20 @@ static int bond_xmit_roundrobin(struct sk_buff *skb, struct net_device *bond_dev
         * send the join/membership reports.  The curr_active_slave found
         * will send all of this type of traffic.
         */
-       if ((iph->protocol == IPPROTO_IGMP) &&
-           (skb->protocol == htons(ETH_P_IP))) {
+       if (iph->protocol == IPPROTO_IGMP && skb->protocol == htons(ETH_P_IP)) {
                slave = bond->curr_active_slave;
-               if (!slave)
-                       goto out;
+               if (slave && slave_can_tx(slave))
+                       bond_dev_queue_xmit(bond, skb, slave->dev);
+               else
+                       bond_xmit_slave_id(bond, skb, 0);
        } else {
-               /*
-                * Concurrent TX may collide on rr_tx_counter; we accept
-                * that as being rare enough not to justify using an
-                * atomic op here.
-                */
-               slave_no = bond->rr_tx_counter++ % bond->slave_cnt;
-
-               bond_for_each_slave(bond, slave) {
-                       slave_no--;
-                       if (slave_no < 0)
-                               break;
-               }
-       }
-
-       start_at = slave;
-       bond_for_each_slave_from(bond, slave, i, start_at) {
-               if (IS_UP(slave->dev) &&
-                   (slave->link == BOND_LINK_UP) &&
-                   bond_is_active_slave(slave)) {
-                       res = bond_dev_queue_xmit(bond, skb, slave->dev);
-                       break;
-               }
-       }
-
-out:
-       if (res) {
-               /* no suitable interface, frame not sent */
-               kfree_skb(skb);
+               bond_xmit_slave_id(bond, skb,
+                                  bond->rr_tx_counter++ % bond->slave_cnt);
        }
 
        return NETDEV_TX_OK;
 }
 
-
 /*
  * in active-backup mode, we know that bond->curr_active_slave is always valid if
  * the bond has a usable interface.
@@ -3857,14 +3869,11 @@ static int bond_xmit_activebackup(struct sk_buff *skb, struct net_device *bond_d
 {
        struct bonding *bond = netdev_priv(bond_dev);
        struct slave *slave;
-       int res = 1;
 
        slave = bond->curr_active_slave;
        if (slave)
-               res = bond_dev_queue_xmit(bond, skb, slave->dev);
-
-       if (res)
-               /* no suitable interface, frame not sent */
+               bond_dev_queue_xmit(bond, skb, slave->dev);
+       else
                kfree_skb(skb);
 
        return NETDEV_TX_OK;
@@ -3878,34 +3887,9 @@ static int bond_xmit_activebackup(struct sk_buff *skb, struct net_device *bond_d
 static int bond_xmit_xor(struct sk_buff *skb, struct net_device *bond_dev)
 {
        struct bonding *bond = netdev_priv(bond_dev);
-       struct slave *slave, *start_at;
-       int slave_no;
-       int i;
-       int res = 1;
-
-       slave_no = bond->xmit_hash_policy(skb, bond->slave_cnt);
-
-       bond_for_each_slave(bond, slave) {
-               slave_no--;
-               if (slave_no < 0)
-                       break;
-       }
-
-       start_at = slave;
 
-       bond_for_each_slave_from(bond, slave, i, start_at) {
-               if (IS_UP(slave->dev) &&
-                   (slave->link == BOND_LINK_UP) &&
-                   bond_is_active_slave(slave)) {
-                       res = bond_dev_queue_xmit(bond, skb, slave->dev);
-                       break;
-               }
-       }
-
-       if (res) {
-               /* no suitable interface, frame not sent */
-               kfree_skb(skb);
-       }
+       bond_xmit_slave_id(bond, skb,
+                          bond->xmit_hash_policy(skb, bond->slave_cnt));
 
        return NETDEV_TX_OK;
 }

diff --git a/drivers/net/bonding/bonding.h b/drivers/net/bonding/bonding.h
index cfd9b493f5b054de2d8c9d3c2fa065fda2d33476..0995974c71acf2eaaf0446c449bf27c1b3e45f9a 100644 (file)
--- a/drivers/net/bonding/bonding.h
+++ b/drivers/net/bonding/bonding.h
@@ -426,10 +426,20 @@ static inline __be32 bond_confirm_addr(struct net_device *dev, __be32 dst, __be3
        return addr;
 }
 
+static inline bool slave_can_tx(struct slave *slave)
+{
+       if (IS_UP(slave->dev) && slave->link == BOND_LINK_UP &&
+           bond_is_active_slave(slave))
+               return true;
+       else
+               return false;
+}
+
 struct bond_net;
 
 struct vlan_entry *bond_next_vlan(struct bonding *bond, struct vlan_entry *curr);
 int bond_dev_queue_xmit(struct bonding *bond, struct sk_buff *skb, struct net_device *slave_dev);
+void bond_xmit_slave_id(struct bonding *bond, struct sk_buff *skb, int slave_id);
 int bond_create(struct net *net, const char *name);
 int bond_create_sysfs(struct bond_net *net);
 void bond_destroy_sysfs(struct bond_net *net);