If an MPLS packet requires segmentation then use mpls_features
to determine if the software implementation should be used.
As no driver advertises MPLS GSO segmentation this will always be
the case.
I had not noticed that this was necessary before as software MPLS GSO
segmentation was already being used in my test environment. I believe that
the reason for that is the skbs in question always had fragments and the
driver I used does not advertise NETIF_F_FRAGLIST (which seems to be the
case for most drivers). Thus software segmentation was activated by
skb_gso_ok().
This introduces the overhead of an extra call to skb_network_protocol()
in the case where where CONFIG_NET_MPLS_GSO is set and
skb->ip_summed == CHECKSUM_NONE.
Thanks to Jesse Gross for prompting me to investigate this.
Signed-off-by: Simon Horman <ho...@verge.net.au>
Acked-by: YAMAMOTO Takashi <yamam...@valinux.co.jp>
---
v5
* As suggested by Yamamoto-san
- Remove unused tmp variable
- Do not use unlikely() for MPLS ethertype check
* Added Ack from Yamamoto-san
v4.2
* As suggested by Eric Dumazet
- Use htons() instead of cpu_to_be16()
- Refactor code to pass type to net_mpls_features.
v4.1
* Following fedback from Thomas Graff and Jesse Gross
- Use ethertype of packet to detect MPLS rather than
relying on mac_len indicating a gap between the end of L2
and the beginning of L3. That assumption seems to
be broken by the GRE GSO code.
- Move mpls_features handling into harmonize_features()
This allows an existing call in there to skb_network_protocol()
to be leveraged.
- Removed acks as the patch has now changed in a material way
v4
* As suggested by YAMAMOTO Takashi
- Correct typos in comment
* Added Ack from YAMAMOTO Takashi
v3
* As requested by David Miller
- Do not mark net_mpls_features as inline
- Correct alignment of parameters
v2
* Added Ack from Jesse Gross
* Removed duplicate 'Thus' from changelog
---
net/core/dev.c | 28 +++++++++++++++++++++++++++-
1 file changed, 27 insertions(+), 1 deletion(-)
diff --git a/net/core/dev.c b/net/core/dev.c
index 0355ca5..f726bfb 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -2498,13 +2498,39 @@ static int dev_gso_segment(struct sk_buff *skb,
netdev_features_t features)
return 0;
}
+/* If MPLS offload request, verify we are testing hardware MPLS features
+ * instead of standard features for the netdev.
+ */
+#ifdef CONFIG_NET_MPLS_GSO
+static netdev_features_t net_mpls_features(struct sk_buff *skb,
+ netdev_features_t features,
+ __be16 type)
+{
+ if (type == htons(ETH_P_MPLS_UC) || type == htons(ETH_P_MPLS_MC))
+ features &= skb->dev->mpls_features;
+
+ return features;
+}
+#else
+static netdev_features_t net_mpls_features(struct sk_buff *skb,
+ netdev_features_t features,
+ __be16 type)
+{
+ return features;
+}
+#endif
+
static netdev_features_t harmonize_features(struct sk_buff *skb,
netdev_features_t features)
{
int tmp;
+ __be16 type;
+
+ type = skb_network_protocol(skb, &tmp);
+ features = net_mpls_features(skb, features, type);
if (skb->ip_summed != CHECKSUM_NONE &&
- !can_checksum_protocol(features, skb_network_protocol(skb, &tmp))) {
+ !can_checksum_protocol(features, type)) {
features &= ~NETIF_F_ALL_CSUM;
} else if (illegal_highdma(skb->dev, skb)) {
features &= ~NETIF_F_SG;
--
2.0.0.rc2
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