Patchwork datapath: Fix build breakage on kernel 2.6.40

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Submitter Zhiyong Wu
Date Nov. 23, 2011, 9:58 a.m.
Message ID <1322042318-4809-1-git-send-email-zwu.kernel@gmail.com>
Download mbox | patch
Permalink /patch/127244/
State Not Applicable
Delegated to: David Miller
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Comments

Zhiyong Wu - Nov. 23, 2011, 9:58 a.m.
From: Zhi Yong Wu <wuzhy@linux.vnet.ibm.com>

Today i played with openvswitch on my workstation with kernel 2.6.40 and found that it break when i built. The issue is introduced by commit ceb176fdb72bb7ce90debc66e1eeb1d25823d30a

Below is the error log.

                 from /home/zwu/work/virt/openvswitch/datapath/linux/genetlink-brcompat.c:10:
/home/zwu/work/virt/openvswitch/datapath/linux/compat/include/linux/skbuff.h:243:20: error: redefinition of ‘skb_reset_mac_len’
include/linux/skbuff.h:1259:20: note: previous definition of ‘skb_reset_mac_len’ was here
make[5]: *** [/home/zwu/work/virt/openvswitch/datapath/linux/genetlink-brcompat.o] Error 1
make[4]: *** [_module_/home/zwu/work/virt/openvswitch/datapath/linux] Error 2
make[4]: Leaving directory `/usr/src/kernels/2.6.40.6-0.fc15.x86_64'
make[3]: *** [default] Error 2
make[3]: Leaving directory `/home/zwu/work/virt/openvswitch/datapath/linux'
make[2]: *** [all-recursive] Error 1
make[2]: Leaving directory `/home/zwu/work/virt/openvswitch/datapath'
make[1]: *** [all-recursive] Error 1
make[1]: Leaving directory `/home/zwu/work/virt/openvswitch'
make: *** [all] Error 2

After this patch is applied, i can successfully do one build and be happy to see that multiple VMs can communicate with each other.


Signed-off-by: Zhi Yong Wu <wuzhy@linux.vnet.ibm.com>
---
 acinclude.m4                                 |    2 ++
 datapath/linux/compat/include/linux/skbuff.h |    2 +-
 2 files changed, 3 insertions(+), 1 deletions(-)
Jesse Gross - Nov. 30, 2011, 9:55 p.m.
On Wed, Nov 23, 2011 at 1:58 AM, Zhi Yong Wu <zwu.kernel@gmail.com> wrote:
> diff --git a/datapath/linux/compat/include/linux/skbuff.h b/datapath/linux/compat/include/linux/skbuff.h
> index 311bfdb..22ba2e6 100644
> --- a/datapath/linux/compat/include/linux/skbuff.h
> +++ b/datapath/linux/compat/include/linux/skbuff.h
> @@ -239,7 +239,7 @@ static inline struct page *skb_frag_page(const skb_frag_t *frag)
>  }
>  #endif
>
> -#if LINUX_VERSION_CODE < KERNEL_VERSION(3,0,0)
> +#ifndef HAVE_SKB_RESET_MAC_LEN

2.6.40 is the early name for 3.0.  Does it work if you just replace
the check with KERNEL_VERSION(2,6,40)?
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Zhiyong Wu - Dec. 2, 2011, 2:25 a.m.
On Thu, Dec 1, 2011 at 5:55 AM, Jesse Gross <jesse@nicira.com> wrote:
> On Wed, Nov 23, 2011 at 1:58 AM, Zhi Yong Wu <zwu.kernel@gmail.com> wrote:
>> diff --git a/datapath/linux/compat/include/linux/skbuff.h b/datapath/linux/compat/include/linux/skbuff.h
>> index 311bfdb..22ba2e6 100644
>> --- a/datapath/linux/compat/include/linux/skbuff.h
>> +++ b/datapath/linux/compat/include/linux/skbuff.h
>> @@ -239,7 +239,7 @@ static inline struct page *skb_frag_page(const skb_frag_t *frag)
>>  }
>>  #endif
>>
>> -#if LINUX_VERSION_CODE < KERNEL_VERSION(3,0,0)
>> +#ifndef HAVE_SKB_RESET_MAC_LEN
>
> 2.6.40 is the early name for 3.0.  Does it work if you just replace
> the check with KERNEL_VERSION(2,6,40)?
Yeah, it can work now, but i don't know if this issue exist on other
old kernel version < 2.6.40.

Should we send one updated patch for this based on your suggestion?
Jesse Gross - Dec. 2, 2011, 11:38 p.m.
On Thu, Dec 1, 2011 at 6:25 PM, Zhi Yong Wu <zwu.kernel@gmail.com> wrote:
> On Thu, Dec 1, 2011 at 5:55 AM, Jesse Gross <jesse@nicira.com> wrote:
>> On Wed, Nov 23, 2011 at 1:58 AM, Zhi Yong Wu <zwu.kernel@gmail.com> wrote:
>>> diff --git a/datapath/linux/compat/include/linux/skbuff.h b/datapath/linux/compat/include/linux/skbuff.h
>>> index 311bfdb..22ba2e6 100644
>>> --- a/datapath/linux/compat/include/linux/skbuff.h
>>> +++ b/datapath/linux/compat/include/linux/skbuff.h
>>> @@ -239,7 +239,7 @@ static inline struct page *skb_frag_page(const skb_frag_t *frag)
>>>  }
>>>  #endif
>>>
>>> -#if LINUX_VERSION_CODE < KERNEL_VERSION(3,0,0)
>>> +#ifndef HAVE_SKB_RESET_MAC_LEN
>>
>> 2.6.40 is the early name for 3.0.  Does it work if you just replace
>> the check with KERNEL_VERSION(2,6,40)?
> Yeah, it can work now, but i don't know if this issue exist on other
> old kernel version < 2.6.40.

Usually we just do these types of checks as we see examples of actual
backporting to avoid having hundreds of tests at configure time.  In
this case, I think the issue is just a difference in how the same
kernel is numbered not backporting, so there isn't really a reason to
believe that this is a bigger problem.

> Should we send one updated patch for this based on your suggestion?

That would be great, thanks.
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Patch

diff --git a/acinclude.m4 b/acinclude.m4
index 648132a..32cdf17 100644
--- a/acinclude.m4
+++ b/acinclude.m4
@@ -233,6 +233,8 @@  AC_DEFUN([OVS_CHECK_LINUX_COMPAT], [
   OVS_GREP_IFELSE([$KSRC/include/linux/skbuff.h], [skb_cow_head])
   OVS_GREP_IFELSE([$KSRC/include/linux/skbuff.h], [skb_transport_header],
                   [OVS_DEFINE([HAVE_SKBUFF_HEADER_HELPERS])])
+  OVS_GREP_IFELSE([$KSRC/include/linux/skbuff.h], [skb_reset_mac_len],
+                  [OVS_DEFINE([HAVE_SKB_RESET_MAC_LEN])])
   OVS_GREP_IFELSE([$KSRC/include/linux/icmpv6.h], [icmp6_hdr],
                   [OVS_DEFINE([HAVE_ICMP6_HDR])])
   OVS_GREP_IFELSE([$KSRC/include/linux/skbuff.h], [skb_warn_if_lro],
diff --git a/datapath/linux/compat/include/linux/skbuff.h b/datapath/linux/compat/include/linux/skbuff.h
index 311bfdb..22ba2e6 100644
--- a/datapath/linux/compat/include/linux/skbuff.h
+++ b/datapath/linux/compat/include/linux/skbuff.h
@@ -239,7 +239,7 @@  static inline struct page *skb_frag_page(const skb_frag_t *frag)
 }
 #endif
 
-#if LINUX_VERSION_CODE < KERNEL_VERSION(3,0,0)
+#ifndef HAVE_SKB_RESET_MAC_LEN
 static inline void skb_reset_mac_len(struct sk_buff *skb)
 {
 	skb->mac_len = skb->network_header - skb->mac_header;