[PATCH net] udp: Fix UDP length on last GSO_PARTIAL segment

[PATCH net] udp: Fix UDP length on last GSO_PARTIAL segment

[Gal Pressman]

Following the cited commit, __udp_gso_segment() writes single MSS length
in the UDP header.
The cited patch doesn't account for the fact that the last segment could
be a GSO skb by itself. This could happen when the size of the packet is
a multiple of MSS, hence the first segment is also the last one (there
is no need for a remainder skb).

When the post-loop segment is a GSO skb, assign the single MSS length in
the UDP header.

Fixes: b10b446ce7ad ("udp: gso: Use single MSS length in UDP header for GSO_PARTIAL")
Reported-by: Matthew Schwartz <matthew.schwartz@linux.dev>
Closes: https://lore.kernel.org/all/6c3fb15e-711d-4b8d-b152-e03d9b05293f@linux.dev/
Tested-by: Matthew Schwartz <matthew.schwartz@linux.dev>
Reviewed-by: Dragos Tatulea <dtatulea@nvidia.com>
Signed-off-by: Gal Pressman <gal@nvidia.com>
---
 net/ipv4/udp_offload.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ipv4/udp_offload.c b/net/ipv4/udp_offload.c
index a0813d425b71..71df45f9488a 100644
--- a/net/ipv4/udp_offload.c
+++ b/net/ipv4/udp_offload.c
@@ -604,7 +604,7 @@ struct sk_buff *__udp_gso_segment(struct sk_buff *gso_skb,
 		       seg->data_len);
 	check = csum16_add(csum16_sub(uh->check, uh->len), newlen);
 
-	uh->len = newlen;
+	uh->len = skb_is_gso(seg) ? msslen : newlen;
 	uh->check = check;
 
 	if (seg->ip_summed == CHECKSUM_PARTIAL)
-- 
2.52.0

Re: [PATCH net] udp: Fix UDP length on last GSO_PARTIAL segment

[Alice Mikityanska]

On Wed, May 13, 2026, at 09:43, Gal Pressman wrote:
> Following the cited commit, __udp_gso_segment() writes single MSS length
> in the UDP header.
> The cited patch doesn't account for the fact that the last segment could
> be a GSO skb by itself. This could happen when the size of the packet is
> a multiple of MSS, hence the first segment is also the last one (there
> is no need for a remainder skb).
>
> When the post-loop segment is a GSO skb, assign the single MSS length in
> the UDP header.
>
> Fixes: b10b446ce7ad ("udp: gso: Use single MSS length in UDP header for 
> GSO_PARTIAL")
> Reported-by: Matthew Schwartz <matthew.schwartz@linux.dev>
> Closes: 
> https://lore.kernel.org/all/6c3fb15e-711d-4b8d-b152-e03d9b05293f@linux.dev/
> Tested-by: Matthew Schwartz <matthew.schwartz@linux.dev>
> Reviewed-by: Dragos Tatulea <dtatulea@nvidia.com>
> Signed-off-by: Gal Pressman <gal@nvidia.com>
> ---
>  net/ipv4/udp_offload.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/net/ipv4/udp_offload.c b/net/ipv4/udp_offload.c
> index a0813d425b71..71df45f9488a 100644
> --- a/net/ipv4/udp_offload.c
> +++ b/net/ipv4/udp_offload.c
> @@ -604,7 +604,7 @@ struct sk_buff *__udp_gso_segment(struct sk_buff *gso_skb,
>  		       seg->data_len);
>  	check = csum16_add(csum16_sub(uh->check, uh->len), newlen);
> 
> -	uh->len = newlen;
> +	uh->len = skb_is_gso(seg) ? msslen : newlen;
>  	uh->check = check;

This is going to have the same checksum bug as your first commit, which
I'm fixing in [1]. You should use the right value of either msslen or
newlen when modifying check a couple of lines above.

That said, maybe you can base your patch on top of my checksum fix? For
the last packet, it will then be:

if (!skb_is_gso(seg))
        newlen = /* the new value */;
/* keep newlen as is otherwise: my newlen is your msslen */
check = csum16_add(csum16_sub(uh->check, uh->len), newlen);
uh->len = newlen;
uh->check = check;

[1]: https://lore.kernel.org/netdev/20260512165648.386518-3-alice.kernel@fastmail.im/

> 
>  	if (seg->ip_summed == CHECKSUM_PARTIAL)
> -- 
> 2.52.0

Re: [PATCH net] udp: Fix UDP length on last GSO_PARTIAL segment

[Gal Pressman]

On 13/05/2026 12:17, Alice Mikityanska wrote:
> On Wed, May 13, 2026, at 09:43, Gal Pressman wrote:
>> Following the cited commit, __udp_gso_segment() writes single MSS length
>> in the UDP header.
>> The cited patch doesn't account for the fact that the last segment could
>> be a GSO skb by itself. This could happen when the size of the packet is
>> a multiple of MSS, hence the first segment is also the last one (there
>> is no need for a remainder skb).
>>
>> When the post-loop segment is a GSO skb, assign the single MSS length in
>> the UDP header.
>>
>> Fixes: b10b446ce7ad ("udp: gso: Use single MSS length in UDP header for 
>> GSO_PARTIAL")
>> Reported-by: Matthew Schwartz <matthew.schwartz@linux.dev>
>> Closes: 
>> https://lore.kernel.org/all/6c3fb15e-711d-4b8d-b152-e03d9b05293f@linux.dev/
>> Tested-by: Matthew Schwartz <matthew.schwartz@linux.dev>
>> Reviewed-by: Dragos Tatulea <dtatulea@nvidia.com>
>> Signed-off-by: Gal Pressman <gal@nvidia.com>
>> ---
>>  net/ipv4/udp_offload.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/net/ipv4/udp_offload.c b/net/ipv4/udp_offload.c
>> index a0813d425b71..71df45f9488a 100644
>> --- a/net/ipv4/udp_offload.c
>> +++ b/net/ipv4/udp_offload.c
>> @@ -604,7 +604,7 @@ struct sk_buff *__udp_gso_segment(struct sk_buff *gso_skb,
>>  		       seg->data_len);
>>  	check = csum16_add(csum16_sub(uh->check, uh->len), newlen);
>>
>> -	uh->len = newlen;
>> +	uh->len = skb_is_gso(seg) ? msslen : newlen;
>>  	uh->check = check;
> 
> This is going to have the same checksum bug as your first commit, which
> I'm fixing in [1]. You should use the right value of either msslen or
> newlen when modifying check a couple of lines above.

I tend to agree that the checksum seems to have the wrong value, the
reason I chose not to change it is because my work only moved the UDP
length assignment from the drivers to the stack.

The "wrong" checksum value was used regardless of my change, and I
prefer not to change it as part of this work.

> 
> That said, maybe you can base your patch on top of my checksum fix? For
> the last packet, it will then be:
> 
> if (!skb_is_gso(seg))
>         newlen = /* the new value */;
> /* keep newlen as is otherwise: my newlen is your msslen */
> check = csum16_add(csum16_sub(uh->check, uh->len), newlen);
> uh->len = newlen;
> uh->check = check;
> 
> [1]: https://lore.kernel.org/netdev/20260512165648.386518-3-alice.kernel@fastmail.im/

As I mentioned in the other thread, this fix goes to net, I can't take
your patch.

Re: [PATCH net] udp: Fix UDP length on last GSO_PARTIAL segment

[Alice Mikityanska]

On Wed, May 13, 2026, at 11:43, Gal Pressman wrote:
> On 13/05/2026 12:17, Alice Mikityanska wrote:
>> On Wed, May 13, 2026, at 09:43, Gal Pressman wrote:
>>> Following the cited commit, __udp_gso_segment() writes single MSS length
>>> in the UDP header.
>>> The cited patch doesn't account for the fact that the last segment could
>>> be a GSO skb by itself. This could happen when the size of the packet is
>>> a multiple of MSS, hence the first segment is also the last one (there
>>> is no need for a remainder skb).
>>>
>>> When the post-loop segment is a GSO skb, assign the single MSS length in
>>> the UDP header.
>>>
>>> Fixes: b10b446ce7ad ("udp: gso: Use single MSS length in UDP header for 
>>> GSO_PARTIAL")
>>> Reported-by: Matthew Schwartz <matthew.schwartz@linux.dev>
>>> Closes: 
>>> https://lore.kernel.org/all/6c3fb15e-711d-4b8d-b152-e03d9b05293f@linux.dev/
>>> Tested-by: Matthew Schwartz <matthew.schwartz@linux.dev>
>>> Reviewed-by: Dragos Tatulea <dtatulea@nvidia.com>
>>> Signed-off-by: Gal Pressman <gal@nvidia.com>
>>> ---
>>>  net/ipv4/udp_offload.c | 2 +-
>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/net/ipv4/udp_offload.c b/net/ipv4/udp_offload.c
>>> index a0813d425b71..71df45f9488a 100644
>>> --- a/net/ipv4/udp_offload.c
>>> +++ b/net/ipv4/udp_offload.c
>>> @@ -604,7 +604,7 @@ struct sk_buff *__udp_gso_segment(struct sk_buff *gso_skb,
>>>  		       seg->data_len);
>>>  	check = csum16_add(csum16_sub(uh->check, uh->len), newlen);
>>>
>>> -	uh->len = newlen;
>>> +	uh->len = skb_is_gso(seg) ? msslen : newlen;
>>>  	uh->check = check;
>> 
>> This is going to have the same checksum bug as your first commit, which
>> I'm fixing in [1]. You should use the right value of either msslen or
>> newlen when modifying check a couple of lines above.
>
> I tend to agree that the checksum seems to have the wrong value, the
> reason I chose not to change it is because my work only moved the UDP
> length assignment from the drivers to the stack.
>
> The "wrong" checksum value was used regardless of my change,

The wrong checksum was visible only inside the driver, and since the
hardware didn't care (due to the offload), it worked well. It was the
driver business to make sure the corresponding hardware likes the
packet. After commit b10b446ce7ad ("udp: gso: Use single MSS length in
UDP header for GSO_PARTIAL"), however, the wrong checksum moved one
abstraction layer higher - to the networking stack, which attempts to
keep the checksum correct for a more generic case. It's not the same,
and while I'm trying to fix one occurrence, I'd prefer not to
introduce more.

> and I
> prefer not to change it as part of this work.
>
>> 
>> That said, maybe you can base your patch on top of my checksum fix? For
>> the last packet, it will then be:
>> 
>> if (!skb_is_gso(seg))
>>         newlen = /* the new value */;
>> /* keep newlen as is otherwise: my newlen is your msslen */
>> check = csum16_add(csum16_sub(uh->check, uh->len), newlen);
>> uh->len = newlen;
>> uh->check = check;
>> 
>> [1]: https://lore.kernel.org/netdev/20260512165648.386518-3-alice.kernel@fastmail.im/
>
> As I mentioned in the other thread, this fix goes to net, I can't take
> your patch.

Ah, that's right. Still, I guess you can take mine to net for the
checksum fix.

Re: [PATCH net] udp: Fix UDP length on last GSO_PARTIAL segment

[Gal Pressman]

On 13/05/2026 13:08, Alice Mikityanska wrote:
> On Wed, May 13, 2026, at 11:43, Gal Pressman wrote:
>> On 13/05/2026 12:17, Alice Mikityanska wrote:
>>> On Wed, May 13, 2026, at 09:43, Gal Pressman wrote:
>>>> Following the cited commit, __udp_gso_segment() writes single MSS length
>>>> in the UDP header.
>>>> The cited patch doesn't account for the fact that the last segment could
>>>> be a GSO skb by itself. This could happen when the size of the packet is
>>>> a multiple of MSS, hence the first segment is also the last one (there
>>>> is no need for a remainder skb).
>>>>
>>>> When the post-loop segment is a GSO skb, assign the single MSS length in
>>>> the UDP header.
>>>>
>>>> Fixes: b10b446ce7ad ("udp: gso: Use single MSS length in UDP header for 
>>>> GSO_PARTIAL")
>>>> Reported-by: Matthew Schwartz <matthew.schwartz@linux.dev>
>>>> Closes: 
>>>> https://lore.kernel.org/all/6c3fb15e-711d-4b8d-b152-e03d9b05293f@linux.dev/
>>>> Tested-by: Matthew Schwartz <matthew.schwartz@linux.dev>
>>>> Reviewed-by: Dragos Tatulea <dtatulea@nvidia.com>
>>>> Signed-off-by: Gal Pressman <gal@nvidia.com>
>>>> ---
>>>>  net/ipv4/udp_offload.c | 2 +-
>>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>>>
>>>> diff --git a/net/ipv4/udp_offload.c b/net/ipv4/udp_offload.c
>>>> index a0813d425b71..71df45f9488a 100644
>>>> --- a/net/ipv4/udp_offload.c
>>>> +++ b/net/ipv4/udp_offload.c
>>>> @@ -604,7 +604,7 @@ struct sk_buff *__udp_gso_segment(struct sk_buff *gso_skb,
>>>>  		       seg->data_len);
>>>>  	check = csum16_add(csum16_sub(uh->check, uh->len), newlen);
>>>>
>>>> -	uh->len = newlen;
>>>> +	uh->len = skb_is_gso(seg) ? msslen : newlen;
>>>>  	uh->check = check;
>>>
>>> This is going to have the same checksum bug as your first commit, which
>>> I'm fixing in [1]. You should use the right value of either msslen or
>>> newlen when modifying check a couple of lines above.
>>
>> I tend to agree that the checksum seems to have the wrong value, the
>> reason I chose not to change it is because my work only moved the UDP
>> length assignment from the drivers to the stack.
>>
>> The "wrong" checksum value was used regardless of my change,
> 
> The wrong checksum was visible only inside the driver, and since the
> hardware didn't care (due to the offload), it worked well. It was the
> driver business to make sure the corresponding hardware likes the
> packet. After commit b10b446ce7ad ("udp: gso: Use single MSS length in
> UDP header for GSO_PARTIAL"), however, the wrong checksum moved one
> abstraction layer higher - to the networking stack, which attempts to
> keep the checksum correct for a more generic case. It's not the same,
> and while I'm trying to fix one occurrence, I'd prefer not to
> introduce more.
> 
>> and I
>> prefer not to change it as part of this work.
>>
>>>
>>> That said, maybe you can base your patch on top of my checksum fix? For
>>> the last packet, it will then be:
>>>
>>> if (!skb_is_gso(seg))
>>>         newlen = /* the new value */;
>>> /* keep newlen as is otherwise: my newlen is your msslen */
>>> check = csum16_add(csum16_sub(uh->check, uh->len), newlen);
>>> uh->len = newlen;
>>> uh->check = check;
>>>
>>> [1]: https://lore.kernel.org/netdev/20260512165648.386518-3-alice.kernel@fastmail.im/
>>
>> As I mentioned in the other thread, this fix goes to net, I can't take
>> your patch.
> 
> Ah, that's right. Still, I guess you can take mine to net for the
> checksum fix.

Do you think it is suitable for net? Would you like to rephrase the
commit message accordingly?

If you can send me an updated version I will take it and submit both (or
you can submit mine if you prefer).

Re: [PATCH net] udp: Fix UDP length on last GSO_PARTIAL segment

[Alice Mikityanska]

On Wed, May 13, 2026, at 13:28, Gal Pressman wrote:
> On 13/05/2026 13:08, Alice Mikityanska wrote:
>> On Wed, May 13, 2026, at 11:43, Gal Pressman wrote:
>>> On 13/05/2026 12:17, Alice Mikityanska wrote:
>>>> On Wed, May 13, 2026, at 09:43, Gal Pressman wrote:
>>>>> Following the cited commit, __udp_gso_segment() writes single MSS length
>>>>> in the UDP header.
>>>>> The cited patch doesn't account for the fact that the last segment could
>>>>> be a GSO skb by itself. This could happen when the size of the packet is
>>>>> a multiple of MSS, hence the first segment is also the last one (there
>>>>> is no need for a remainder skb).
>>>>>
>>>>> When the post-loop segment is a GSO skb, assign the single MSS length in
>>>>> the UDP header.
>>>>>
>>>>> Fixes: b10b446ce7ad ("udp: gso: Use single MSS length in UDP header for 
>>>>> GSO_PARTIAL")
>>>>> Reported-by: Matthew Schwartz <matthew.schwartz@linux.dev>
>>>>> Closes: 
>>>>> https://lore.kernel.org/all/6c3fb15e-711d-4b8d-b152-e03d9b05293f@linux.dev/
>>>>> Tested-by: Matthew Schwartz <matthew.schwartz@linux.dev>
>>>>> Reviewed-by: Dragos Tatulea <dtatulea@nvidia.com>
>>>>> Signed-off-by: Gal Pressman <gal@nvidia.com>
>>>>> ---
>>>>>  net/ipv4/udp_offload.c | 2 +-
>>>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>>>>
>>>>> diff --git a/net/ipv4/udp_offload.c b/net/ipv4/udp_offload.c
>>>>> index a0813d425b71..71df45f9488a 100644
>>>>> --- a/net/ipv4/udp_offload.c
>>>>> +++ b/net/ipv4/udp_offload.c
>>>>> @@ -604,7 +604,7 @@ struct sk_buff *__udp_gso_segment(struct sk_buff *gso_skb,
>>>>>  		       seg->data_len);
>>>>>  	check = csum16_add(csum16_sub(uh->check, uh->len), newlen);
>>>>>
>>>>> -	uh->len = newlen;
>>>>> +	uh->len = skb_is_gso(seg) ? msslen : newlen;
>>>>>  	uh->check = check;
>>>>
>>>> This is going to have the same checksum bug as your first commit, which
>>>> I'm fixing in [1]. You should use the right value of either msslen or
>>>> newlen when modifying check a couple of lines above.
>>>
>>> I tend to agree that the checksum seems to have the wrong value, the
>>> reason I chose not to change it is because my work only moved the UDP
>>> length assignment from the drivers to the stack.
>>>
>>> The "wrong" checksum value was used regardless of my change,
>> 
>> The wrong checksum was visible only inside the driver, and since the
>> hardware didn't care (due to the offload), it worked well. It was the
>> driver business to make sure the corresponding hardware likes the
>> packet. After commit b10b446ce7ad ("udp: gso: Use single MSS length in
>> UDP header for GSO_PARTIAL"), however, the wrong checksum moved one
>> abstraction layer higher - to the networking stack, which attempts to
>> keep the checksum correct for a more generic case. It's not the same,
>> and while I'm trying to fix one occurrence, I'd prefer not to
>> introduce more.
>> 
>>> and I
>>> prefer not to change it as part of this work.
>>>
>>>>
>>>> That said, maybe you can base your patch on top of my checksum fix? For
>>>> the last packet, it will then be:
>>>>
>>>> if (!skb_is_gso(seg))
>>>>         newlen = /* the new value */;
>>>> /* keep newlen as is otherwise: my newlen is your msslen */
>>>> check = csum16_add(csum16_sub(uh->check, uh->len), newlen);
>>>> uh->len = newlen;
>>>> uh->check = check;
>>>>
>>>> [1]: https://lore.kernel.org/netdev/20260512165648.386518-3-alice.kernel@fastmail.im/
>>>
>>> As I mentioned in the other thread, this fix goes to net, I can't take
>>> your patch.
>> 
>> Ah, that's right. Still, I guess you can take mine to net for the
>> checksum fix.
>
> Do you think it is suitable for net?

This is always a mystery to me... I've had different experiences:
sometimes I am asked to resubmit less important fixes to -next,
sometimes a fix is a fix and must go to net. This one is a refactoring
useful for my further patches + the checksum fix, which we get for free
and which I considered not important enough to submit to net (hardware
offload fixes the checksum in most cases anyway). Following the "a fix
is a fix" logic, we may try sending it to net. What do you think?

> Would you like to rephrase the
> commit message accordingly?
>
> If you can send me an updated version I will take it and submit both (or
> you can submit mine if you prefer).

Re: [PATCH net] udp: Fix UDP length on last GSO_PARTIAL segment

[Gal Pressman]

On 13/05/2026 14:48, Alice Mikityanska wrote:
> On Wed, May 13, 2026, at 13:28, Gal Pressman wrote:
>> On 13/05/2026 13:08, Alice Mikityanska wrote:
>>> On Wed, May 13, 2026, at 11:43, Gal Pressman wrote:
>>>> On 13/05/2026 12:17, Alice Mikityanska wrote:
>>>>> On Wed, May 13, 2026, at 09:43, Gal Pressman wrote:
>>>>>> Following the cited commit, __udp_gso_segment() writes single MSS length
>>>>>> in the UDP header.
>>>>>> The cited patch doesn't account for the fact that the last segment could
>>>>>> be a GSO skb by itself. This could happen when the size of the packet is
>>>>>> a multiple of MSS, hence the first segment is also the last one (there
>>>>>> is no need for a remainder skb).
>>>>>>
>>>>>> When the post-loop segment is a GSO skb, assign the single MSS length in
>>>>>> the UDP header.
>>>>>>
>>>>>> Fixes: b10b446ce7ad ("udp: gso: Use single MSS length in UDP header for 
>>>>>> GSO_PARTIAL")
>>>>>> Reported-by: Matthew Schwartz <matthew.schwartz@linux.dev>
>>>>>> Closes: 
>>>>>> https://lore.kernel.org/all/6c3fb15e-711d-4b8d-b152-e03d9b05293f@linux.dev/
>>>>>> Tested-by: Matthew Schwartz <matthew.schwartz@linux.dev>
>>>>>> Reviewed-by: Dragos Tatulea <dtatulea@nvidia.com>
>>>>>> Signed-off-by: Gal Pressman <gal@nvidia.com>
>>>>>> ---
>>>>>>  net/ipv4/udp_offload.c | 2 +-
>>>>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>>>>>
>>>>>> diff --git a/net/ipv4/udp_offload.c b/net/ipv4/udp_offload.c
>>>>>> index a0813d425b71..71df45f9488a 100644
>>>>>> --- a/net/ipv4/udp_offload.c
>>>>>> +++ b/net/ipv4/udp_offload.c
>>>>>> @@ -604,7 +604,7 @@ struct sk_buff *__udp_gso_segment(struct sk_buff *gso_skb,
>>>>>>  		       seg->data_len);
>>>>>>  	check = csum16_add(csum16_sub(uh->check, uh->len), newlen);
>>>>>>
>>>>>> -	uh->len = newlen;
>>>>>> +	uh->len = skb_is_gso(seg) ? msslen : newlen;
>>>>>>  	uh->check = check;
>>>>>
>>>>> This is going to have the same checksum bug as your first commit, which
>>>>> I'm fixing in [1]. You should use the right value of either msslen or
>>>>> newlen when modifying check a couple of lines above.
>>>>
>>>> I tend to agree that the checksum seems to have the wrong value, the
>>>> reason I chose not to change it is because my work only moved the UDP
>>>> length assignment from the drivers to the stack.
>>>>
>>>> The "wrong" checksum value was used regardless of my change,
>>>
>>> The wrong checksum was visible only inside the driver, and since the
>>> hardware didn't care (due to the offload), it worked well. It was the
>>> driver business to make sure the corresponding hardware likes the
>>> packet. After commit b10b446ce7ad ("udp: gso: Use single MSS length in
>>> UDP header for GSO_PARTIAL"), however, the wrong checksum moved one
>>> abstraction layer higher - to the networking stack, which attempts to
>>> keep the checksum correct for a more generic case. It's not the same,
>>> and while I'm trying to fix one occurrence, I'd prefer not to
>>> introduce more.
>>>
>>>> and I
>>>> prefer not to change it as part of this work.
>>>>
>>>>>
>>>>> That said, maybe you can base your patch on top of my checksum fix? For
>>>>> the last packet, it will then be:
>>>>>
>>>>> if (!skb_is_gso(seg))
>>>>>         newlen = /* the new value */;
>>>>> /* keep newlen as is otherwise: my newlen is your msslen */
>>>>> check = csum16_add(csum16_sub(uh->check, uh->len), newlen);
>>>>> uh->len = newlen;
>>>>> uh->check = check;
>>>>>
>>>>> [1]: https://lore.kernel.org/netdev/20260512165648.386518-3-alice.kernel@fastmail.im/
>>>>
>>>> As I mentioned in the other thread, this fix goes to net, I can't take
>>>> your patch.
>>>
>>> Ah, that's right. Still, I guess you can take mine to net for the
>>> checksum fix.
>>
>> Do you think it is suitable for net?
> 
> This is always a mystery to me... I've had different experiences:
> sometimes I am asked to resubmit less important fixes to -next,
> sometimes a fix is a fix and must go to net. This one is a refactoring
> useful for my further patches + the checksum fix, which we get for free
> and which I considered not important enough to submit to net (hardware
> offload fixes the checksum in most cases anyway). Following the "a fix
> is a fix" logic, we may try sending it to net. What do you think?

IMHO, the motivation you provided in your previous message for the
checksum fix is convincing, but as I said, I think the commit message
should be phrased to explain the bug rather than the refactoring (and
add a Fixes tag).