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Date: Mon, 20 Apr 2015 22:01:44 -0400 (EDT) From: David Miller <davem@...emloft.net> To: tom@...bertland.com Cc: netdev@...r.kernel.org Subject: Re: [PATCH net-next 0/2] net: Fix "hw csum failure" message flood for ppp tunnel From: Tom Herbert <tom@...bertland.com> Date: Mon, 20 Apr 2015 14:10:03 -0700 > This patch set addresses bug "Bug 95171 - "hw csum failure" message > flood for ppp tunnel since upgrade to 3.16". The problem is that pppoe > is being used over UDP with UDP checksusm enabled. On receive > checksum conversion turns checksum-unnecessary in checksum- > complete. The PPP receive functions do no properly pull > the checksum over its headers, so that when an encapsulated > checksums is considered the checksum-complete value is incorrect. > > This patch adds skb_checksum_complete_unset which can be called > in the receive path in lieu of pulling checksum complete in > layer. This is useful when the packet is being modified (e.g. > decompressed) and the checksum-complete value is no longer > relevant. > > In the ppp_receive_frame we call skb_checksum_complete_unset to toss > out checksum-complete. This should eliminate the reported messages. > Alternatively, we could add skb_postpull_rcsum and probably > special case handling for VJ compression if maintaining the > checksum-complete is needed (not clear to me this is worth the > effort). > > I haven't tested this since setting up the failure scenario doesn't > seem trivial to configure. I'm preemptively applying this, but it's really important for folks to give this some good testing. Thanks Tom. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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