[PATCH net 2/2] net: core: explicitly select a txq before doing l2 forwarding
From: Jason Wang
Date: Sun Jan 05 2014 - 22:35:23 EST
Currently, the tx queue were selected implicitly in ndo_dfwd_start_xmit(). The
will cause several issues:
- NETIF_F_LLTX was forced for macvlan device in this case which lead extra lock
contention.
- dev_hard_start_xmit() was called with NULL txq which bypasses the net device
watchdog
- dev_hard_start_xmit() does not check txq everywhere which will lead a crash
when tso is disabled for lower device.
Fix this by explicitly introducing a select queue method just for l2 forwarding
offload (ndo_dfwd_select_queue), and introducing dfwd_direct_xmit() to do the
queue selecting and transmitting for l2 forwarding.
With this fixes, NETIF_F_LLTX could be preserved for macvlan and there's no need
to check txq against NULL in dev_hard_start_xmit().
In the future, it was also required for macvtap l2 forwarding support since it
provides a necessary synchronization method.
Cc: John Fastabend <john.r.fastabend@xxxxxxxxx>
Cc: Neil Horman <nhorman@xxxxxxxxxxxxx>
Cc: e1000-devel@xxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
---
drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 15 +++++++++----
drivers/net/macvlan.c | 3 +-
include/linux/netdevice.h | 11 +++++++++
net/core/dev.c | 28 ++++++++++++++++++++++++-
4 files changed, 49 insertions(+), 8 deletions(-)
diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
index cc06854..ee71cf7 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
@@ -7629,16 +7629,20 @@ static void ixgbe_fwd_del(struct net_device *pdev, void *priv)
kfree(fwd_adapter);
}
+static u16 ixgbe_fwd_select_queue(struct net_device *dev, struct sk_buff *skb,
+ void *priv)
+{
+ struct ixgbe_fwd_adapter *fwd_adapter = priv;
+ return skb->queue_mapping + fwd_adapter->tx_base_queue;
+}
+
static netdev_tx_t ixgbe_fwd_xmit(struct sk_buff *skb,
struct net_device *dev,
void *priv)
{
struct ixgbe_fwd_adapter *fwd_adapter = priv;
- unsigned int queue;
- struct ixgbe_ring *tx_ring;
-
- queue = skb->queue_mapping + fwd_adapter->tx_base_queue;
- tx_ring = fwd_adapter->real_adapter->tx_ring[queue];
+ struct ixgbe_ring *tx_ring =
+ fwd_adapter->real_adapter->tx_ring[skb->queue_mapping];
return __ixgbe_xmit_frame(skb, dev, tx_ring);
}
@@ -7689,6 +7693,7 @@ static const struct net_device_ops ixgbe_netdev_ops = {
.ndo_bridge_getlink = ixgbe_ndo_bridge_getlink,
.ndo_dfwd_add_station = ixgbe_fwd_add,
.ndo_dfwd_del_station = ixgbe_fwd_del,
+ .ndo_dfwd_select_queue = ixgbe_fwd_select_queue,
.ndo_dfwd_start_xmit = ixgbe_fwd_xmit,
};
diff --git a/drivers/net/macvlan.c b/drivers/net/macvlan.c
index 5360f73..2cbbce3 100644
--- a/drivers/net/macvlan.c
+++ b/drivers/net/macvlan.c
@@ -299,7 +299,7 @@ netdev_tx_t macvlan_start_xmit(struct sk_buff *skb,
if (vlan->fwd_priv) {
skb->dev = vlan->lowerdev;
- ret = dev_hard_start_xmit(skb, skb->dev, NULL, vlan->fwd_priv);
+ ret = dfwd_direct_xmit(skb, skb->dev, vlan->fwd_priv);
} else {
ret = macvlan_queue_xmit(skb, dev);
}
@@ -366,7 +366,6 @@ static int macvlan_open(struct net_device *dev)
if (IS_ERR_OR_NULL(vlan->fwd_priv)) {
vlan->fwd_priv = NULL;
} else {
- dev->features &= ~NETIF_F_LLTX;
return 0;
}
}
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index d9a550b..dbfd476 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -975,6 +975,11 @@ struct netdev_phys_port_id {
* by 'ndo_dfwd_add_station'. 'pdev' is the net device backing
* the station and priv is the structure returned by the add
* operation.
+ * u16 (*ndo_dfwd_select_queue)(struct net_device *dev,
+ * struct sk_buff *skb,
+ * void *priv);
+ * Called to decide which queue to xmit over the accelerated station when
+ * device supports multiple transmit queues.
* netdev_tx_t (*ndo_dfwd_start_xmit)(struct sk_buff *skb,
* struct net_device *dev,
* void *priv);
@@ -1123,6 +1128,10 @@ struct net_device_ops {
void (*ndo_dfwd_del_station)(struct net_device *pdev,
void *priv);
+ u16 (*ndo_dfwd_select_queue)(struct net_device *dev,
+ struct sk_buff *skb,
+ void *priv);
+
netdev_tx_t (*ndo_dfwd_start_xmit) (struct sk_buff *skb,
struct net_device *dev,
void *priv);
@@ -2416,6 +2425,8 @@ int dev_set_mac_address(struct net_device *, struct sockaddr *);
int dev_change_carrier(struct net_device *, bool new_carrier);
int dev_get_phys_port_id(struct net_device *dev,
struct netdev_phys_port_id *ppid);
+int dfwd_direct_xmit(struct sk_buff *skb, struct net_device *dev,
+ void *accel_priv);
int dev_hard_start_xmit(struct sk_buff *skb, struct net_device *dev,
struct netdev_queue *txq, void *accel_priv);
int dev_forward_skb(struct net_device *dev, struct sk_buff *skb);
diff --git a/net/core/dev.c b/net/core/dev.c
index 4fc1722..bc2b03f 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -2538,6 +2538,32 @@ static inline int skb_needs_linearize(struct sk_buff *skb,
!(features & NETIF_F_SG)));
}
+int dfwd_direct_xmit(struct sk_buff *skb, struct net_device *dev,
+ void *accel_priv)
+{
+ struct netdev_queue *txq;
+ int ret = NETDEV_TX_BUSY;
+ int index;
+
+ BUG_ON(!dev->netdev_ops->ndo_dfwd_select_queue);
+ index = dev->netdev_ops->ndo_dfwd_select_queue(dev, skb,
+ accel_priv);
+
+ local_bh_disable();
+
+ skb_set_queue_mapping(skb, index);
+ txq = netdev_get_tx_queue(dev, index);
+
+ HARD_TX_LOCK(dev, txq, smp_processor_id());
+ if (!netif_xmit_frozen_or_stopped(txq))
+ ret = dev_hard_start_xmit(skb, dev, txq, accel_priv);
+ HARD_TX_UNLOCK(dev, txq);
+
+ local_bh_enable();
+ return ret;
+}
+EXPORT_SYMBOL_GPL(dfwd_direct_xmit);
+
int dev_hard_start_xmit(struct sk_buff *skb, struct net_device *dev,
struct netdev_queue *txq, void *accel_priv)
{
@@ -2611,7 +2637,7 @@ int dev_hard_start_xmit(struct sk_buff *skb, struct net_device *dev,
rc = ops->ndo_start_xmit(skb, dev);
trace_net_dev_xmit(skb, rc, dev, skb_len);
- if (rc == NETDEV_TX_OK && txq)
+ if (rc == NETDEV_TX_OK)
txq_trans_update(txq);
return rc;
}
--
1.7.1
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/