Messages in this thread Patch in this message | | | Subject | Re: [PATCH] Revert "net: pskb_trim_rcsum() and CHECKSUM_COMPLETE are friends" | From | Eric Dumazet <> | Date | Mon, 18 Jun 2018 11:18:46 -0700 |
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On 06/18/2018 10:54 AM, Andreas Schwab wrote: > On Jun 17 2018, Eric Dumazet <eric.dumazet@gmail.com> wrote: > >> Oh this is silly, please try : >> >> diff --git a/net/core/skbuff.c b/net/core/skbuff.c >> index c642304f178ce0a4e1358d59e45032a39f76fb3f..54dd9c18ecad817812898d6f335e1794a07dabbe 100644 >> --- a/net/core/skbuff.c >> +++ b/net/core/skbuff.c >> @@ -1845,10 +1845,9 @@ EXPORT_SYMBOL(___pskb_trim); >> int pskb_trim_rcsum_slow(struct sk_buff *skb, unsigned int len) >> { >> if (skb->ip_summed == CHECKSUM_COMPLETE) { >> - int delta = skb->len - len; >> + __wsum csumdiff = skb_checksum(skb, len, skb->len - len, 0); >> >> - skb->csum = csum_sub(skb->csum, >> - skb_checksum(skb, len, delta, 0)); >> + skb->csum = csum_block_sub(skb->csum, csumdiff, len); >> } >> return __pskb_trim(skb, len); >> } > > That doesn't help either. > > Andreas. >
Then maybe NIC provided csum is not correct.
It does not compute a checksum on all the frame, but part of it.
You could use this patch to double check.
diff --git a/drivers/net/ethernet/sun/sungem.c b/drivers/net/ethernet/sun/sungem.c index 7a16d40a72d13cf1d522e8a3a396c826fe76f9b9..277859ea73e35271a10b02011120fca248ec8e71 100644 --- a/drivers/net/ethernet/sun/sungem.c +++ b/drivers/net/ethernet/sun/sungem.c @@ -857,6 +857,11 @@ static int gem_rx(struct gem *gp, int work_to_do) csum = (__force __sum16)htons((status & RXDCTRL_TCPCSUM) ^ 0xffff); skb->csum = csum_unfold(csum); + { + __wsum rsum = csum_partial(skb->data + ETH_HLEN, len - ETH_HLEN, 0); + if (csum != csum_fold(rsum)) + pr_err_ratelimited("sungem wrong csum : %x/%x, len %u bytes\n", csum, csum_fold(rsum), len); + } skb->ip_summed = CHECKSUM_COMPLETE; skb->protocol = eth_type_trans(skb, gp->dev);
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