netdev - Re: [Patch net-next] net: dump more useful information in netdev_rx_csum

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Date:   Sat, 10 Nov 2018 10:44:24 +0800
From:   Yunsheng Lin <linyunsheng@...wei.com>
To:     Cong Wang <xiyou.wangcong@...il.com>
CC:     Linux Kernel Network Developers <netdev@...r.kernel.org>
Subject: Re: [Patch net-next] net: dump more useful information in
 netdev_rx_csum_fault()

On 2018/11/10 10:09, Cong Wang wrote:
> On Fri, Nov 9, 2018 at 6:02 PM Yunsheng Lin <linyunsheng@...wei.com> wrote:
>>
>> On 2018/11/10 9:42, Cong Wang wrote:
>>> On Fri, Nov 9, 2018 at 5:39 PM Yunsheng Lin <linyunsheng@...wei.com> wrote:
>>>>
>>>> On 2018/11/10 3:43, Cong Wang wrote:
>>>>> Currently netdev_rx_csum_fault() only shows a device name,
>>>>> we need more information about the skb for debugging.
>>>>>
>>>>> Sample output:
>>>>>
>>>>>  ens3: hw csum failure
>>>>>  dev features: 0x0000000000014b89
>>>>>  skb len=84 data_len=0 gso_size=0 gso_type=0 ip_summed=0 csum=0, csum_complete_sw=0, csum_valid=0
>>>>>
>>>>> Signed-off-by: Cong Wang <xiyou.wangcong@...il.com>
>>>>> ---
>>>>>  include/linux/netdevice.h |  5 +++--
>>>>>  net/core/datagram.c       |  6 +++---
>>>>>  net/core/dev.c            | 10 ++++++++--
>>>>>  net/sunrpc/socklib.c      |  2 +-
>>>>>  4 files changed, 15 insertions(+), 8 deletions(-)
>>>>>
>>>>> diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
>>>>> index 857f8abf7b91..fabcd9fa6cf7 100644
>>>>> --- a/include/linux/netdevice.h
>>>>> +++ b/include/linux/netdevice.h
>>>>> @@ -4332,9 +4332,10 @@ static inline bool can_checksum_protocol(netdev_features_t features,
>>>>>  }
>>>>>
>>>>>  #ifdef CONFIG_BUG
>>>>> -void netdev_rx_csum_fault(struct net_device *dev);
>>>>> +void netdev_rx_csum_fault(struct net_device *dev, struct sk_buff *skb);
>>>>>  #else
>>>>> -static inline void netdev_rx_csum_fault(struct net_device *dev)
>>>>> +static inline void netdev_rx_csum_fault(struct net_device *dev,
>>>>> +                                     struct sk_buff *skb)
>>>>>  {
>>>>>  }
>>>>>  #endif
>>>>> diff --git a/net/core/datagram.c b/net/core/datagram.c
>>>>> index 57f3a6fcfc1e..d8f4d55cd6c5 100644
>>>>> --- a/net/core/datagram.c
>>>>> +++ b/net/core/datagram.c
>>>>> @@ -736,7 +736,7 @@ __sum16 __skb_checksum_complete_head(struct sk_buff *skb, int len)
>>>>>       if (likely(!sum)) {
>>>>>               if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE) &&
>>>>>                   !skb->csum_complete_sw)
>>>>> -                     netdev_rx_csum_fault(skb->dev);
>>>>> +                     netdev_rx_csum_fault(skb->dev, skb);
>>>>>       }
>>>>>       if (!skb_shared(skb))
>>>>>               skb->csum_valid = !sum;
>>>>> @@ -756,7 +756,7 @@ __sum16 __skb_checksum_complete(struct sk_buff *skb)
>>>>>       if (likely(!sum)) {
>>>>>               if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE) &&
>>>>>                   !skb->csum_complete_sw)
>>>>> -                     netdev_rx_csum_fault(skb->dev);
>>>>> +                     netdev_rx_csum_fault(skb->dev, skb);
>>>>>       }
>>>>>
>>>>>       if (!skb_shared(skb)) {
>>>>> @@ -810,7 +810,7 @@ int skb_copy_and_csum_datagram_msg(struct sk_buff *skb,
>>>>>
>>>>>               if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE) &&
>>>>>                   !skb->csum_complete_sw)
>>>>> -                     netdev_rx_csum_fault(NULL);
>>>>> +                     netdev_rx_csum_fault(NULL, skb);
>>>>>       }
>>>>>       return 0;
>>>>>  fault:
>>>>> diff --git a/net/core/dev.c b/net/core/dev.c
>>>>> index 0ffcbdd55fa9..2b337df26117 100644
>>>>> --- a/net/core/dev.c
>>>>> +++ b/net/core/dev.c
>>>>> @@ -3091,10 +3091,16 @@ EXPORT_SYMBOL(__skb_gso_segment);
>>>>>
>>>>>  /* Take action when hardware reception checksum errors are detected. */
>>>>>  #ifdef CONFIG_BUG
>>>>> -void netdev_rx_csum_fault(struct net_device *dev)
>>>>> +void netdev_rx_csum_fault(struct net_device *dev, struct sk_buff *skb)
>>>>>  {
>>>>>       if (net_ratelimit()) {
>>>>>               pr_err("%s: hw csum failure\n", dev ? dev->name : "<unknown>");
>>>>> +             if (dev)
>>>>> +                     pr_err("dev features: %pNF\n", &dev->features);
>>>>> +             pr_err("skb len=%d data_len=%d gso_size=%d gso_type=%d ip_summed=%d csum=%x, csum_complete_sw=%d, csum_valid=%d\n",
>>>>> +                    skb->len, skb->data_len, skb_shinfo(skb)->gso_size,
>>>>> +                    skb_shinfo(skb)->gso_type, skb->ip_summed, skb->csum,
>>>>> +                    skb->csum_complete_sw, skb->csum_valid);
>>>>
>>>>
>>>> This function also have the netdev available, use netdev_err to log the error?
>>>
>>> It is apparently not me who picked pr_err() from the beginning,
>>> I just follow that pr_err(). If you are not happy with it, please send
>>> a followup.
>>
>> Yes, but perhaps it is something to improve.
> 
> 
> Sure, no one stops you from improving it in a followup patch. :)
> 
> 
>> When using the netdev, then maybe it does not have to check if dev is null, because
>> netdev_err has handled the netdev being NULL case.
>> Maybe I missed something that netdev can not be used here?
>> If not, maybe I can send a followup.
>>
> 
> Maybe. Again, my patch intends to add a few debugging logs,
> not to convert pr_err() to whatever else, they are totally different
> goals. I choose pr_err() only because I follow the existing one,
> not to say which one is better than the other.

Ok. :)

> 
> Thanks.
> 
> .
>