net: adjust skb_gso_segment() for calling in rx path

skb_gso_segment() is almost always called in tx path,
except for openvswitch. It calls this function when
it receives the packet and tries to queue it to user-space.
In this special case, the ->ip_summed check inside
skb_gso_segment() is no longer true, as ->ip_summed value
has different meanings on rx path.

This patch adjusts skb_gso_segment() so that we can at least
avoid such warnings on checksum.

Cc: Jesse Gross <jesse@nicira.com>
Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: Cong Wang <amwang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 16 insertions, 5 deletions

diff --git a/net/core/dev.c b/net/core/dev.c
index 2b275a7b8677..65da698c500b 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -2327,18 +2327,29 @@ out:
 }
 EXPORT_SYMBOL(skb_checksum_help);
 
+/* openvswitch calls this on rx path, so we need a different check.
+ */
+static inline bool skb_needs_check(struct sk_buff *skb, bool tx_path)
+{
+        if (tx_path)
+                return skb->ip_summed != CHECKSUM_PARTIAL;
+        else
+                return skb->ip_summed == CHECKSUM_NONE;
+}
+
 /**
- *      skb_gso_segment - Perform segmentation on skb.
+ *      __skb_gso_segment - Perform segmentation on skb.
  *      @skb: buffer to segment
  *      @features: features for the output path (see dev->features)
+ *      @tx_path: whether it is called in TX path
  *
  *      This function segments the given skb and returns a list of segments.
  *
  *      It may return NULL if the skb requires no segmentation.  This is
  *      only possible when GSO is used for verifying header integrity.
  */
-struct sk_buff *skb_gso_segment(struct sk_buff *skb,
-        netdev_features_t features)
+struct sk_buff *__skb_gso_segment(struct sk_buff *skb,
+                                  netdev_features_t features, bool tx_path)
 {
         struct sk_buff *segs = ERR_PTR(-EPROTONOSUPPORT);
         struct packet_offload *ptype;
@@ -2361,7 +2372,7 @@ struct sk_buff *skb_gso_segment(struct sk_buff *skb,
         skb->mac_len = skb->network_header - skb->mac_header;
         __skb_pull(skb, skb->mac_len);
 
-        if (unlikely(skb->ip_summed != CHECKSUM_PARTIAL)) {
+        if (unlikely(skb_needs_check(skb, tx_path))) {
                 skb_warn_bad_offload(skb);
 
                 if (skb_header_cloned(skb) &&
@@ -2390,7 +2401,7 @@ struct sk_buff *skb_gso_segment(struct sk_buff *skb,
 
         return segs;
 }
-EXPORT_SYMBOL(skb_gso_segment);
+EXPORT_SYMBOL(__skb_gso_segment);
 
 /* Take action when hardware reception checksum errors are detected. */
 #ifdef CONFIG_BUG