From: "Morten Brørup" <mb@smartsharesystems.com>
To: "Hongzhi Guo" <guohongzhi1@huawei.com>, <olivier.matz@6wind.com>
Cc: <dev@dpdk.org>, <stable@dpdk.org>, <stephen@networkplumber.org>,
<thomas@monjalon.net>, <konstantin.ananyev@intel.com>,
<ferruh.yigit@intel.com>, <nicolas.chautru@intel.com>,
<zhoujingbin@huawei.com>, <chenchanghu@huawei.com>,
<jerry.lilijun@huawei.com>, <haifeng.lin@huawei.com>
Subject: Re: [dpdk-stable] [dpdk-dev] [PATCH] net: fix checksum on big endian CPUs
Date: Fri, 10 Jul 2020 14:20:08 +0200 [thread overview]
Message-ID: <98CBD80474FA8B44BF855DF32C47DC35C61117@smartserver.smartshare.dk> (raw)
In-Reply-To: <20200710114313.7412-1-guohongzhi1@huawei.com>
> From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Hongzhi Guo
> Sent: Friday, July 10, 2020 1:43 PM
>
> With current code, the checksum of odd-length buffers is wrong on
> big endian CPUs: the last byte is not properly summed to the
> accumulator.
>
> Fix this by left-shifting the remaining byte by 8. For instance,
> if the last byte is 0x42, we should add 0x4200 to the accumulator
> on big endian CPUs.
>
> This change is similar to what is suggested in Errata 3133 of
> RFC 1071.
>
> Fixes: 6006818cfb26("net: new checksum functions")
> Cc: stable@dpdk.org
>
> Signed-off-by: Hongzhi Guo <guohongzhi1@huawei.com>
> ---
> v2:
> * Explain the logic in the commit log
> * Fixed commit title
> ---
> ---
> lib/librte_net/rte_ip.h | 7 +++++--
> 1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/lib/librte_net/rte_ip.h b/lib/librte_net/rte_ip.h
> index 292f63fd7..4fb0e314a 100644
> --- a/lib/librte_net/rte_ip.h
> +++ b/lib/librte_net/rte_ip.h
> @@ -139,8 +139,11 @@ __rte_raw_cksum(const void *buf, size_t len,
> uint32_t sum)
> }
>
> /* if length is in odd bytes */
> - if (len == 1)
> - sum += *((const uint8_t *)u16_buf);
> + if (len == 1) {
> + uint16_t left = 0;
> + *(uint8_t *)&left = *(const uint8_t *)u16_buf;
> + sum += left;
> + }
>
> return sum;
> }
> --
> 2.21.0.windows.1
>
This is correct for both big and little endian CPUs.
Reviewed-by: Morten Brørup <mb@smartsharesystems.com>
next prev parent reply other threads:[~2020-07-10 12:20 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-10 11:43 [dpdk-stable] " Hongzhi Guo
2020-07-10 12:20 ` Morten Brørup [this message]
2020-07-10 12:37 ` [dpdk-stable] [dpdk-dev] " Olivier Matz
2020-07-10 21:11 ` Thomas Monjalon
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