A question about include/linux/socket.h

A question about include/linux/socket.h

[Sinan Akpolat]

Hi,

I am writing CAN bus userspace code and I get a compiler error stating 
"sa_family_t is not defined" for "include/linux/can.h". sa_family_t is 
defined in include/linux/socket.h but it is not carried to userspace 
kernel headers.

  When I searched about it I saw that a similar problem in 
include/linux/netlink.h and include/linux/socket.h is fixed by the patch:

https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/include?id=6602a4baf4d1a73cc4685a39ef859e1c5ddf654c. 


I also read about UAPI but I can't use newer kernels.

I searched the kernel git repo but couldn't find a similar patch for 
can.h. When you search for "sa_family_t" in include/linux directory you 
can see it is used in more than 10 files and I guess none of those files 
will compile since they won't be able to find typedef sa_family_t (just 
like can.h).

So my question is:
- Does anyone remember a patch fixing this issue?
- Should the typedef sa_family_t moved to userspace kernel headers? Or 
should structs containing sa_family_t type variables moved away from 
user space?

I have been using the file manually defining sa_family_t but I wanted to 
ask. I am using kernel version 2.6.37 but I guess can.h file was 
unchanged until 3.5.

Thanks

Re: A question about include/linux/socket.h

[Ben Hutchings]

On Wed, 2013-08-28 at 16:45 +0300, Sinan Akpolat wrote:
> Hi,
> 
> I am writing CAN bus userspace code and I get a compiler error stating 
> "sa_family_t is not defined" for "include/linux/can.h". sa_family_t is 
> defined in include/linux/socket.h but it is not carried to userspace 
> kernel headers.
> 
>   When I searched about it I saw that a similar problem in 
> include/linux/netlink.h and include/linux/socket.h is fixed by the patch:
> 
> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/include?id=6602a4baf4d1a73cc4685a39ef859e1c5ddf654c. 

You probably want commit bcb949b8847655516ba499ca75cd8529f167e360, which
fixed include/linux/can.h.

> I also read about UAPI but I can't use newer kernels.
> 
> I searched the kernel git repo but couldn't find a similar patch for 
> can.h. When you search for "sa_family_t" in include/linux directory you 
> can see it is used in more than 10 files and I guess none of those files 
> will compile since they won't be able to find typedef sa_family_t (just 
> like can.h).
> 
> So my question is:
> - Does anyone remember a patch fixing this issue?
> - Should the typedef sa_family_t moved to userspace kernel headers? Or 
> should structs containing sa_family_t type variables moved away from 
> user space?

No, sa_family_t is normally defined by the C library headers.  But
kernel headers generally don't include those (for good reasons).  So
kernel headers should instead define and use __kernel_sa_family_t, and
that's what they do now (mostly).

Ben.

> I have been using the file manually defining sa_family_t but I wanted to 
> ask. I am using kernel version 2.6.37 but I guess can.h file was 
> unchanged until 3.5.

-- 
Ben Hutchings, Staff Engineer, Solarflare
Not speaking for my employer; that's the marketing department's job.
They asked us to note that Solarflare product names are trademarked.

Re: A question about include/linux/socket.h

[Sinan Akpolat]

28.8.2013 17:27 tarihinde, Ben Hutchings yazdı:
> On Wed, 2013-08-28 at 16:45 +0300, Sinan Akpolat wrote:
>> Hi,
>>
>> I am writing CAN bus userspace code and I get a compiler error stating
>> "sa_family_t is not defined" for "include/linux/can.h". sa_family_t is
>> defined in include/linux/socket.h but it is not carried to userspace
>> kernel headers.
>>
>>    When I searched about it I saw that a similar problem in
>> include/linux/netlink.h and include/linux/socket.h is fixed by the patch:
>>
>> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/include?id=6602a4baf4d1a73cc4685a39ef859e1c5ddf654c.
> You probably want commit bcb949b8847655516ba499ca75cd8529f167e360, which
> fixed include/linux/can.h.
Yeah, that's the one. Thank you very much, I couldn't find it using cgit 
interface in git.kernel.org.
>
>> I also read about UAPI but I can't use newer kernels.
>>
>> I searched the kernel git repo but couldn't find a similar patch for
>> can.h. When you search for "sa_family_t" in include/linux directory you
>> can see it is used in more than 10 files and I guess none of those files
>> will compile since they won't be able to find typedef sa_family_t (just
>> like can.h).
>>
>> So my question is:
>> - Does anyone remember a patch fixing this issue?
>> - Should the typedef sa_family_t moved to userspace kernel headers? Or
>> should structs containing sa_family_t type variables moved away from
>> user space?
> No, sa_family_t is normally defined by the C library headers.  But
> kernel headers generally don't include those (for good reasons).  So
> kernel headers should instead define and use __kernel_sa_family_t, and
> that's what they do now (mostly).
>
> Ben.
Thanks for the info.
>
>> I have been using the file manually defining sa_family_t but I wanted to
>> ask. I am using kernel version 2.6.37 but I guess can.h file was
>> unchanged until 3.5.