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authorEric Dumazet <edumazet@google.com>2018-04-18 11:43:15 -0700
committerDavid S. Miller <davem@davemloft.net>2018-04-19 13:44:11 -0400
commit88078d98d1bb085d72af8437707279e203524fa5 (patch)
treebf20f9ebb371aa14ce699ad9be0afc093babd04b /net/core/skbuff.c
parent292eba02dbb4c41da840e462e51ee97d80d873d1 (diff)
downloadop-kernel-dev-88078d98d1bb085d72af8437707279e203524fa5.zip
op-kernel-dev-88078d98d1bb085d72af8437707279e203524fa5.tar.gz
net: pskb_trim_rcsum() and CHECKSUM_COMPLETE are friends
After working on IP defragmentation lately, I found that some large packets defeat CHECKSUM_COMPLETE optimization because of NIC adding zero paddings on the last (small) fragment. While removing the padding with pskb_trim_rcsum(), we set skb->ip_summed to CHECKSUM_NONE, forcing a full csum validation, even if all prior fragments had CHECKSUM_COMPLETE set. We can instead compute the checksum of the part we are trimming, usually smaller than the part we keep. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/core/skbuff.c')
-rw-r--r--net/core/skbuff.c14
1 files changed, 14 insertions, 0 deletions
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 345b518..ff49e35 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -1839,6 +1839,20 @@ done:
}
EXPORT_SYMBOL(___pskb_trim);
+/* Note : use pskb_trim_rcsum() instead of calling this directly
+ */
+int pskb_trim_rcsum_slow(struct sk_buff *skb, unsigned int len)
+{
+ if (skb->ip_summed == CHECKSUM_COMPLETE) {
+ int delta = skb->len - len;
+
+ skb->csum = csum_sub(skb->csum,
+ skb_checksum(skb, len, delta, 0));
+ }
+ return __pskb_trim(skb, len);
+}
+EXPORT_SYMBOL(pskb_trim_rcsum_slow);
+
/**
* __pskb_pull_tail - advance tail of skb header
* @skb: buffer to reallocate
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