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* [dpdk-stable] [PATCH] net: fix checksum on big endian CPUs
@ 2020-07-10 11:43 Hongzhi Guo
  2020-07-10 12:20 ` [dpdk-stable] [dpdk-dev] " Morten Brørup
  0 siblings, 1 reply; 4+ messages in thread
From: Hongzhi Guo @ 2020-07-10 11:43 UTC (permalink / raw)
  To: olivier.matz
  Cc: dev, stable, stephen, thomas, mb, konstantin.ananyev,
	ferruh.yigit, nicolas.chautru, zhoujingbin, chenchanghu,
	jerry.lilijun, haifeng.lin, guohongzhi1

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



^ permalink raw reply	[flat|nested] 4+ messages in thread

* Re: [dpdk-stable] [dpdk-dev] [PATCH] net: fix checksum on big endian CPUs
  2020-07-10 11:43 [dpdk-stable] [PATCH] net: fix checksum on big endian CPUs Hongzhi Guo
@ 2020-07-10 12:20 ` Morten Brørup
  2020-07-10 12:37   ` Olivier Matz
  0 siblings, 1 reply; 4+ messages in thread
From: Morten Brørup @ 2020-07-10 12:20 UTC (permalink / raw)
  To: Hongzhi Guo, olivier.matz
  Cc: dev, stable, stephen, thomas, konstantin.ananyev, ferruh.yigit,
	nicolas.chautru, zhoujingbin, chenchanghu, jerry.lilijun,
	haifeng.lin

> 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>


^ permalink raw reply	[flat|nested] 4+ messages in thread

* Re: [dpdk-stable] [dpdk-dev] [PATCH] net: fix checksum on big endian CPUs
  2020-07-10 12:20 ` [dpdk-stable] [dpdk-dev] " Morten Brørup
@ 2020-07-10 12:37   ` Olivier Matz
  2020-07-10 21:11     ` Thomas Monjalon
  0 siblings, 1 reply; 4+ messages in thread
From: Olivier Matz @ 2020-07-10 12:37 UTC (permalink / raw)
  To: Morten Brørup
  Cc: Hongzhi Guo, dev, stable, stephen, thomas, konstantin.ananyev,
	ferruh.yigit, nicolas.chautru, zhoujingbin, chenchanghu,
	jerry.lilijun, haifeng.lin

On Fri, Jul 10, 2020 at 02:20:08PM +0200, Morten Brørup wrote:
> > 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>

Acked-by: Olivier Matz <olivier.matz@6wind.com>

Thanks!


^ permalink raw reply	[flat|nested] 4+ messages in thread

* Re: [dpdk-stable] [dpdk-dev] [PATCH] net: fix checksum on big endian CPUs
  2020-07-10 12:37   ` Olivier Matz
@ 2020-07-10 21:11     ` Thomas Monjalon
  0 siblings, 0 replies; 4+ messages in thread
From: Thomas Monjalon @ 2020-07-10 21:11 UTC (permalink / raw)
  To: Hongzhi Guo
  Cc: Morten Brørup, stable, dev, stable, stephen,
	konstantin.ananyev, ferruh.yigit, nicolas.chautru, zhoujingbin,
	chenchanghu, jerry.lilijun, haifeng.lin

10/07/2020 14:37, Olivier Matz:
> On Fri, Jul 10, 2020 at 02:20:08PM +0200, Morten Brørup wrote:
> > > 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>
> > 
> > Reviewed-by: Morten Brørup <mb@smartsharesystems.com>
> 
> Acked-by: Olivier Matz <olivier.matz@6wind.com>

Applied, thank you Hongzhi Guo, we want more patches like this :-)




^ permalink raw reply	[flat|nested] 4+ messages in thread

end of thread, other threads:[~2020-07-10 21:11 UTC | newest]

Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-07-10 11:43 [dpdk-stable] [PATCH] net: fix checksum on big endian CPUs Hongzhi Guo
2020-07-10 12:20 ` [dpdk-stable] [dpdk-dev] " Morten Brørup
2020-07-10 12:37   ` Olivier Matz
2020-07-10 21:11     ` Thomas Monjalon

patches for DPDK stable branches

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