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| author | Eric Dumazet <edumazet@google.com> | 2018-10-10 22:30:11 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-10-18 10:13:26 +0300 |
| commit | 791521e2e377f66ef5ee6e5002dec758234d8d32 (patch) | |
| tree | f0a526ab60f5952d36a495df1ca66d4fb21155bd /net/core | |
| parent | a8444b1ccb20339774af58e40ad42296074fb484 (diff) | |
| download | linux-791521e2e377f66ef5ee6e5002dec758234d8d32.tar.xz | |
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>
(cherry picked from commit 88078d98d1bb085d72af8437707279e203524fa5)
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'net/core')
| -rw-r--r-- | net/core/skbuff.c | 14 |
1 files changed, 14 insertions, 0 deletions
diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 4e545e4432eb..038ec74fa131 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -1578,6 +1578,20 @@ 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 |