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From: David Miller <davem@davemloft.net>
To: kyk.segfault@gmail.com
Cc: David.Laight@aculab.com, eric.dumazet@gmail.com,
	netdev@vger.kernel.org, willemdebruijn.kernel@gmail.com
Subject: Re: [PATCH v3] net: Make skb_segment not to compute checksum if network controller supports checksumming
Date: Sat, 21 Mar 2020 20:06:34 -0700 (PDT)	[thread overview]
Message-ID: <20200321.200634.534398039682553516.davem@davemloft.net> (raw)
In-Reply-To: <1584434318-27980-1-git-send-email-kyk.segfault@gmail.com>

From: Yadu Kishore <kyk.segfault@gmail.com>
Date: Tue, 17 Mar 2020 14:08:38 +0530

> 
>> I think you can rebase and submit against net-next.
> 
>> If your patch isn't active in the networking development patchwork instance,
>> it is not pending to be applied and you must resend it.
> 
> Rebasing the patch on net-next and resending it.
> 
> Problem:
> TCP checksum in the output path is not being offloaded during GSO
> in the following case:
> The network driver does not support scatter-gather but supports
> checksum offload with NETIF_F_HW_CSUM.
> 
> Cause:
> skb_segment calls skb_copy_and_csum_bits if the network driver
> does not announce NETIF_F_SG. It does not check if the driver
> supports NETIF_F_HW_CSUM.
> So for devices which might want to offload checksum but do not support SG
> there is currently no way to do so if GSO is enabled.
> 
> Solution:
> In skb_segment check if the network controller does checksum and if so
> call skb_copy_bits instead of skb_copy_and_csum_bits.
> 
> Testing:
> Without the patch, ran iperf TCP traffic with NETIF_F_HW_CSUM enabled
> in the network driver. Observed the TCP checksum offload is not happening
> since the skbs received by the driver in the output path have
> skb->ip_summed set to CHECKSUM_NONE.
> 
> With the patch ran iperf TCP traffic and observed that TCP checksum
> is being offloaded with skb->ip_summed set to CHECKSUM_PARTIAL.
> Also tested with the patch by disabling NETIF_F_HW_CSUM in the driver
> to cover the newly introduced if-else code path in skb_segment.
> 
> Link: https://lore.kernel.org/netdev/CA+FuTSeYGYr3Umij+Mezk9CUcaxYwqEe5sPSuXF8jPE2yMFJAw@mail.gmail.com
> Signed-off-by: Yadu Kishore <kyk.segfault@gmail.com>

Willem, please review and ACK/NACK.

Thank you.

  reply	other threads:[~2020-03-22  3:06 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-04  5:55 TCP checksum not offloaded during GSO Yadu Kishore
2020-02-05 21:43 ` Willem de Bruijn
2020-02-21  5:13   ` [PATCH] net: Make skb_segment not to compute checksum if network controller supports checksumming Yadu Kishore
2020-02-23  2:41     ` Willem de Bruijn
2020-02-28  5:24       ` Yadu Kishore
2020-02-28 14:30         ` Willem de Bruijn
2020-02-28 20:01           ` David Miller
2020-03-02  6:51             ` [PATCH v2] " Yadu Kishore
2020-03-02  8:42               ` Yadu Kishore
2020-03-02 15:19                 ` David Laight
2020-03-03  9:15                   ` Yadu Kishore
2020-03-03  9:56                     ` David Laight
2020-03-05  6:32                       ` Yadu Kishore
2020-03-05 16:06                         ` Willem de Bruijn
2020-03-05 17:00                           ` David Laight
2020-03-05 17:19                             ` Eric Dumazet
2020-03-06 17:12                               ` David Laight
2020-03-13  6:36                                 ` Yadu Kishore
2020-03-13 13:57                                   ` Willem de Bruijn
2020-03-13 14:04                                     ` David Laight
2020-03-13 18:05                                   ` David Miller
2020-03-17  8:38                                     ` [PATCH v3] " Yadu Kishore
2020-03-22  3:06                                       ` David Miller [this message]
2020-03-22 14:40                                       ` Willem de Bruijn
2020-03-23 20:00                                       ` David Miller
2020-03-22 19:53                                 ` [PATCH v2] " Tom Herbert
2020-03-23  9:15                                   ` David Laight
2020-02-06 12:13 ` TCP checksum not offloaded during GSO David Laight

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