netdev - Re: [PATCH net] net: avoid skb_warn_bad

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Date:   Tue, 08 Aug 2017 21:39:49 -0700 (PDT)
From:   David Miller <davem@...emloft.net>
To:     willemdebruijn.kernel@...il.com
Cc:     netdev@...r.kernel.org, eric.dumazet@...il.com,
        xiangxia.m.yue@...il.com, willemb@...gle.com
Subject: Re: [PATCH net] net: avoid skb_warn_bad_offload false positives on
 UFO

From: Willem de Bruijn <willemdebruijn.kernel@...il.com>
Date: Tue,  8 Aug 2017 14:22:55 -0400

> From: Willem de Bruijn <willemb@...gle.com>
> 
> skb_warn_bad_offload triggers a warning when an skb enters the GSO
> stack at __skb_gso_segment that does not have CHECKSUM_PARTIAL
> checksum offload set.
> 
> Commit b2504a5dbef3 ("net: reduce skb_warn_bad_offload() noise")
> observed that SKB_GSO_DODGY producers can trigger the check and
> that passing those packets through the GSO handlers will fix it
> up. But, the software UFO handler will set ip_summed to
> CHECKSUM_NONE.
> 
> When __skb_gso_segment is called from the receive path, this
> triggers the warning again.
> 
> Make UFO set CHECKSUM_UNNECESSARY instead of CHECKSUM_NONE. On
> Tx these two are equivalent. On Rx, this better matches the
> skb state (checksum computed), as CHECKSUM_NONE here means no
> checksum computed.
> 
> See also this thread for context:
> http://patchwork.ozlabs.org/patch/799015/
> 
> Fixes: b2504a5dbef3 ("net: reduce skb_warn_bad_offload() noise")
> Signed-off-by: Willem de Bruijn <willemb@...gle.com>

Applied and queued up for -stable, thank you.