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From: Eric Dumazet <eric.dumazet@gmail.com>
To: Tariq Toukan <tariqt@mellanox.com>,
	"David S. Miller" <davem@davemloft.net>
Cc: netdev@vger.kernel.org, Eran Ben Elisha <eranbe@mellanox.com>,
	Saeed Mahameed <saeedm@mellanox.com>,
	Eric Dumazet <edumazet@google.com>
Subject: Re: [PATCH net V2] net/mlx4_en: Force CHECKSUM_NONE for short ethernet frames
Date: Mon, 11 Feb 2019 09:24:01 -0800	[thread overview]
Message-ID: <860ee92a-6547-342e-0e3e-024562328a90@gmail.com> (raw)
In-Reply-To: <1549901057-2614-1-git-send-email-tariqt@mellanox.com>



On 02/11/2019 08:04 AM, Tariq Toukan wrote:
> From: Saeed Mahameed <saeedm@mellanox.com>
> 
> When an ethernet frame is padded to meet the minimum ethernet frame
> size, the padding octets are not covered by the hardware checksum.
> Fortunately the padding octets are usually zero's, which don't affect
> checksum. However, it is not guaranteed. For example, switches might
> choose to make other use of these octets.
> This repeatedly causes kernel hardware checksum fault.
> 
> Prior to the cited commit below, skb checksum was forced to be
> CHECKSUM_NONE when padding is detected. After it, we need to keep
> skb->csum updated. However, fixing up CHECKSUM_COMPLETE requires to
> verify and parse IP headers, it does not worth the effort as the packets
> are so small that CHECKSUM_COMPLETE has no significant advantage.
> 
> Future work: when reporting checksum complete is not an option for
> IP non-TCP/UDP packets, we can actually fallback to report checksum
> unnecessary, by looking at cqe IPOK bit.
> 
> Fixes: 88078d98d1bb ("net: pskb_trim_rcsum() and CHECKSUM_COMPLETE are friends")
> Cc: Eric Dumazet <edumazet@google.com>
> Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
> Signed-off-by: Tariq Toukan <tariqt@mellanox.com>

Thanks Tariq and Saeed

Reviewed-by: Eric Dumazet <edumazet@google.com>


  reply	other threads:[~2019-02-11 17:24 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-02-11 16:04 [PATCH net V2] net/mlx4_en: Force CHECKSUM_NONE for short ethernet frames Tariq Toukan
2019-02-11 17:24 ` Eric Dumazet [this message]
2019-02-12 17:28 ` David Miller

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