2014-06-13 15:37:54

by Tom Herbert

Subject: [-next] Regression: ssh log in slowdown

> Thanks, I applied the series "[PATCH 0/4] Checksum fixes", and the fix
> above, but it doesn't help.
>
> Note that I'm also using NFS root, which doesn't seem to be affected.
> I can happily run "ls -R /" on the serial console during the 10 s delay
in ssh.
>
Geert,

Thanks for your patience!

Can you try one more patch below with the series applied? Also, can you
look at 'netstat -s' to see if UDP checksum errors are being reported.

Thanks,
Tom

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index fdb510c..4b722bc 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -2820,8 +2820,8 @@ static inline __sum16 __skb_checksum_validate_complete(struct sk_buff *skb,
if (complete || skb->len <= CHECKSUM_BREAK) {
__sum16 csum;

+ /* skb->csum valid set in __skb_checksum_complete */
csum = __skb_checksum_complete(skb);
- skb->csum_valid = !csum;
return csum;
}

diff --git a/net/core/datagram.c b/net/core/datagram.c
index cf6cc4e..488dd1a 100644
--- a/net/core/datagram.c
+++ b/net/core/datagram.c
@@ -744,6 +744,7 @@ __sum16 __skb_checksum_complete_head(struct sk_buff *skb, int len)
!skb->csum_complete_sw)
netdev_rx_csum_fault(skb->dev);
}
+ skb->csum_valid = !sum;
return sum;
}
EXPORT_SYMBOL(__skb_checksum_complete_head);
@@ -767,6 +768,7 @@ __sum16 __skb_checksum_complete(struct sk_buff *skb)
skb->csum = csum;
skb->ip_summed = CHECKSUM_COMPLETE;
skb->csum_complete_sw = 1;
+ skb->csum_valid = !sum;

return sum;
}
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index bf92824..9cd5344 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -689,6 +689,9 @@ static void __copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
new->ooo_okay = old->ooo_okay;
new->no_fcs = old->no_fcs;
new->encapsulation = old->encapsulation;
+ new->encap_hdr_csum = old->encap_hdr_csum;
+ new->csum_valid = old->csum_valid;
+ new->csum_complete_sw = old->csum_complete_sw;
#ifdef CONFIG_XFRM
new->sp = secpath_get(old->sp);
#endif

2014-06-15 08:43:04

by Geert Uytterhoeven

Subject: Re: [-next] Regression: ssh log in slowdown

Hi Tom,

On Fri, Jun 13, 2014 at 5:37 PM, Tom Herbert <[email protected]> wrote:
>> Thanks, I applied the series "[PATCH 0/4] Checksum fixes", and the fix
>> above, but it doesn't help.
>>
>> Note that I'm also using NFS root, which doesn't seem to be affected.
>> I can happily run "ls -R /" on the serial console during the 10 s delay
> in ssh.
>
> Can you try one more patch below with the series applied? Also, can you

This patch fixes the issue. Thanks!

> look at 'netstat -s' to see if UDP checksum errors are being reported.

Indeed, errors are reported under Udp/InCsumErrors.
With this new patch, no errors are reported.

Thanks!

Gr{oetje,eeting}s,

Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- [email protected]

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds