[ovs-dev] [PATCH v2 2/2] datapath: Move segmentation compatibility code into a compatibility function
Simon Horman
horms at verge.net.au
Tue Sep 24 07:44:06 UTC 2013
Move segmentation compatibility code out of netdev_send and into
rpl_dev_queue_xmit(), a compatibility function used in place
of dev_queue_xmit() as necessary.
As suggested by Jesse Gross.
Some minor though verbose implementation notes:
* This rpl_dev_queue_xmit() endeavours to return a valid error code or
zero on success as per dev_queue_xmit(). The exception is that when
dev_queue_xmit() is called in a loop only the status of the last call is
taken into account, thus ignoring any errors returned by previous calls.
This is derived from the previous calls to dev_queue_xmit() in a loop
where netdev_send() ignores the return value of dev_queue_xmit()
entirely.
* netdev_send() continues to ignore the value of dev_queue_xmit().
So the discussion of the return value of rpl_dev_queue_xmit()
above is has no bearing on run-time behaviour.
* The return value of netdev_send() may differ from the previous
implementation in the case where segmentation is performed before
calling the real dev_queue_xmit(). This is because previously in
this case netdev_send() would return the combined length of the
skbs resulting from segmentation. Whereas the current code
always returns the length of the original skb.
Signed-off-by: Simon Horman <horms at verge.net.au>
--
v2
- Remove stray '// 1'
- Move rpl_dev_queue_xmit definition from gso.h to linux/netdevice.h
- Correct compilation errors with kernels older than 2.6.27
---
datapath/linux/compat/gso.c | 80 +++++++++++++++++++++++++
datapath/linux/compat/include/linux/netdevice.h | 5 ++
datapath/vport-netdev.c | 78 +-----------------------
3 files changed, 87 insertions(+), 76 deletions(-)
diff --git a/datapath/linux/compat/gso.c b/datapath/linux/compat/gso.c
index 30332a2..32f906c 100644
--- a/datapath/linux/compat/gso.c
+++ b/datapath/linux/compat/gso.c
@@ -36,6 +36,86 @@
#include "gso.h"
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,37) && \
+ !defined(HAVE_VLAN_BUG_WORKAROUND)
+#include <linux/module.h>
+
+static int vlan_tso __read_mostly;
+module_param(vlan_tso, int, 0644);
+MODULE_PARM_DESC(vlan_tso, "Enable TSO for VLAN packets");
+#else
+#define vlan_tso true
+#endif
+
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,37)
+static bool dev_supports_vlan_tx(struct net_device *dev)
+{
+#if defined(HAVE_VLAN_BUG_WORKAROUND)
+ return dev->features & NETIF_F_HW_VLAN_TX;
+#else
+ /* Assume that the driver is buggy. */
+ return false;
+#endif
+}
+
+int rpl_dev_queue_xmit(struct sk_buff *skb)
+{
+#undef dev_queue_xmit
+ int err = -ENOMEM;
+
+ if (vlan_tx_tag_present(skb) && !dev_supports_vlan_tx(skb->dev)) {
+ int features;
+
+ features = netif_skb_features(skb);
+
+ if (!vlan_tso)
+ features &= ~(NETIF_F_TSO | NETIF_F_TSO6 |
+ NETIF_F_UFO | NETIF_F_FSO);
+
+ skb = __vlan_put_tag(skb, skb->vlan_proto, vlan_tx_tag_get(skb));
+ if (unlikely(!skb))
+ return err;
+ vlan_set_tci(skb, 0);
+
+ if (netif_needs_gso(skb, features)) {
+ struct sk_buff *nskb;
+
+ nskb = skb_gso_segment(skb, features);
+ if (!nskb) {
+ if (unlikely(skb_cloned(skb) &&
+ pskb_expand_head(skb, 0, 0, GFP_ATOMIC)))
+ goto drop;
+
+ skb_shinfo(skb)->gso_type &= ~SKB_GSO_DODGY;
+ goto xmit;
+ }
+
+ if (IS_ERR(nskb)) {
+ err = PTR_ERR(nskb);
+ goto drop;
+ }
+ consume_skb(skb);
+ skb = nskb;
+
+ do {
+ nskb = skb->next;
+ skb->next = NULL;
+ err = dev_queue_xmit(skb);
+ skb = nskb;
+ } while (skb);
+
+ return err;
+ }
+ }
+xmit:
+ return dev_queue_xmit(skb);
+
+drop:
+ kfree_skb(skb);
+ return err;
+}
+#endif /* kernel version < 2.6.37 */
+
static __be16 __skb_network_protocol(struct sk_buff *skb)
{
__be16 type = skb->protocol;
diff --git a/datapath/linux/compat/include/linux/netdevice.h b/datapath/linux/compat/include/linux/netdevice.h
index 4e2b7f5..2b2c855 100644
--- a/datapath/linux/compat/include/linux/netdevice.h
+++ b/datapath/linux/compat/include/linux/netdevice.h
@@ -120,4 +120,9 @@ static inline void netdev_upper_dev_unlink(struct net_device *dev,
}
#endif
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,37)
+#define dev_queue_xmit rpl_dev_queue_xmit
+int dev_queue_xmit(struct sk_buff *skb);
+#endif
+
#endif
diff --git a/datapath/vport-netdev.c b/datapath/vport-netdev.c
index 31680fd..4d934b5 100644
--- a/datapath/vport-netdev.c
+++ b/datapath/vport-netdev.c
@@ -34,17 +34,6 @@
#include "vport-internal_dev.h"
#include "vport-netdev.h"
-#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,37) && \
- !defined(HAVE_VLAN_BUG_WORKAROUND)
-#include <linux/module.h>
-
-static int vlan_tso __read_mostly;
-module_param(vlan_tso, int, 0644);
-MODULE_PARM_DESC(vlan_tso, "Enable TSO for VLAN packets");
-#else
-#define vlan_tso true
-#endif
-
static void netdev_port_receive(struct vport *vport, struct sk_buff *skb);
#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,39)
@@ -259,19 +248,6 @@ static unsigned int packet_length(const struct sk_buff *skb)
return length;
}
-static bool dev_supports_vlan_tx(struct net_device *dev)
-{
-#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,37)
- /* Software fallback means every device supports vlan_tci on TX. */
- return true;
-#elif defined(HAVE_VLAN_BUG_WORKAROUND)
- return dev->features & NETIF_F_HW_VLAN_TX;
-#else
- /* Assume that the driver is buggy. */
- return false;
-#endif
-}
-
static int netdev_send(struct vport *vport, struct sk_buff *skb)
{
struct netdev_vport *netdev_vport = netdev_vport_priv(vport);
@@ -282,65 +258,15 @@ static int netdev_send(struct vport *vport, struct sk_buff *skb)
net_warn_ratelimited("%s: dropped over-mtu packet: %d > %d\n",
netdev_vport->dev->name,
packet_length(skb), mtu);
- goto drop;
+ kfree_skb(skb);
+ return 0;
}
skb->dev = netdev_vport->dev;
-
- if (vlan_tx_tag_present(skb) && !dev_supports_vlan_tx(skb->dev)) {
- int features;
-
- features = netif_skb_features(skb);
-
- if (!vlan_tso)
- features &= ~(NETIF_F_TSO | NETIF_F_TSO6 |
- NETIF_F_UFO | NETIF_F_FSO);
-
- skb = __vlan_put_tag(skb, skb->vlan_proto, vlan_tx_tag_get(skb));
- if (unlikely(!skb))
- return 0;
- vlan_set_tci(skb, 0);
-
- if (netif_needs_gso(skb, features)) {
- struct sk_buff *nskb;
-
- nskb = skb_gso_segment(skb, features);
- if (!nskb) {
- if (unlikely(skb_cloned(skb) &&
- pskb_expand_head(skb, 0, 0, GFP_ATOMIC)))
- goto drop;
-
- skb_shinfo(skb)->gso_type &= ~SKB_GSO_DODGY;
- goto xmit;
- }
-
- if (IS_ERR(nskb))
- goto drop;
- consume_skb(skb);
- skb = nskb;
-
- len = 0;
- do {
- nskb = skb->next;
- skb->next = NULL;
- len += skb->len;
- dev_queue_xmit(skb);
- skb = nskb;
- } while (skb);
-
- return len;
- }
- }
-
-xmit:
len = skb->len;
dev_queue_xmit(skb);
return len;
-
-drop:
- kfree_skb(skb);
- return 0;
}
/* Returns null if this device is not attached to a datapath. */
--
1.8.4
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