When compiling inside the kernel include linux/stddef.h instead of
stddef.h. When I compile this header file in backports for power PC I
run into a conflict with ptrdiff_t. I was unable to reproduce this in
mainline kernel. I still would like to fix this problem in the kernel.
Fixes: 6989310f5d43 ("wireless: Use offsetof instead of custom macro.")
Signed-off-by: Hauke Mehrtens <[email protected]>
---
include/uapi/linux/wireless.h | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/include/uapi/linux/wireless.h b/include/uapi/linux/wireless.h
index a2c006a364e0..24f3371ad826 100644
--- a/include/uapi/linux/wireless.h
+++ b/include/uapi/linux/wireless.h
@@ -74,7 +74,11 @@
#include <linux/socket.h> /* for "struct sockaddr" et al */
#include <linux/if.h> /* for IFNAMSIZ and co... */
-#include <stddef.h> /* for offsetof */
+#ifdef __KERNEL__
+# include <linux/stddef.h> /* for offsetof */
+#else
+# include <stddef.h> /* for offsetof */
+#endif
/***************************** VERSION *****************************/
/*
--
2.20.1
On Thursday 21 May 2020 22:14:22 CEST Hauke Mehrtens wrote:
> When compiling inside the kernel include linux/stddef.h instead of
> stddef.h. When I compile this header file in backports for power PC I
> run into a conflict with ptrdiff_t. I was unable to reproduce this in
> mainline kernel. I still would like to fix this problem in the kernel.
>
> Fixes: 6989310f5d43 ("wireless: Use offsetof instead of custom macro.")
> Signed-off-by: Hauke Mehrtens <[email protected]>
> ---
> include/uapi/linux/wireless.h | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/include/uapi/linux/wireless.h b/include/uapi/linux/wireless.h
> index a2c006a364e0..24f3371ad826 100644
> --- a/include/uapi/linux/wireless.h
> +++ b/include/uapi/linux/wireless.h
> @@ -74,7 +74,11 @@
> #include <linux/socket.h> /* for "struct sockaddr" et al */
> #include <linux/if.h> /* for IFNAMSIZ and co... */
>
> -#include <stddef.h> /* for offsetof */
> +#ifdef __KERNEL__
> +# include <linux/stddef.h> /* for offsetof */
> +#else
> +# include <stddef.h> /* for offsetof */
> +#endif
Hello,
This patch also solves a warning I encountered when I launched sparse
(with make C=1):
/usr/lib/gcc-cross/arm-linux-gnueabihf/9/include/stddef.h:406:9: warning: preprocessor token offsetof redefined
./include/linux/stddef.h:17:9: this was the original definition
However, I wonder if it useful to keep 'include <stddef.h>' when this file
is included from userspace. If it does not compile anymore, there is
problem somewhere else, no?
(Globally, I always find suspicious a kernel source that includes a system
header)
--
J?r?me Pouiller
On 5/25/20 11:35 AM, Jérôme Pouiller wrote:
> On Thursday 21 May 2020 22:14:22 CEST Hauke Mehrtens wrote:
>> When compiling inside the kernel include linux/stddef.h instead of
>> stddef.h. When I compile this header file in backports for power PC I
>> run into a conflict with ptrdiff_t. I was unable to reproduce this in
>> mainline kernel. I still would like to fix this problem in the kernel.
>>
>> Fixes: 6989310f5d43 ("wireless: Use offsetof instead of custom macro.")
>> Signed-off-by: Hauke Mehrtens <[email protected]>
>> ---
>> include/uapi/linux/wireless.h | 6 +++++-
>> 1 file changed, 5 insertions(+), 1 deletion(-)
>>
>> diff --git a/include/uapi/linux/wireless.h b/include/uapi/linux/wireless.h
>> index a2c006a364e0..24f3371ad826 100644
>> --- a/include/uapi/linux/wireless.h
>> +++ b/include/uapi/linux/wireless.h
>> @@ -74,7 +74,11 @@
>> #include <linux/socket.h> /* for "struct sockaddr" et al */
>> #include <linux/if.h> /* for IFNAMSIZ and co... */
>>
>> -#include <stddef.h> /* for offsetof */
>> +#ifdef __KERNEL__
>> +# include <linux/stddef.h> /* for offsetof */
>> +#else
>> +# include <stddef.h> /* for offsetof */
>> +#endif
>
> Hello,
>
> This patch also solves a warning I encountered when I launched sparse
> (with make C=1):
>
> /usr/lib/gcc-cross/arm-linux-gnueabihf/9/include/stddef.h:406:9: warning: preprocessor token offsetof redefined
> ./include/linux/stddef.h:17:9: this was the original definition
>
> However, I wonder if it useful to keep 'include <stddef.h>' when this file
> is included from userspace. If it does not compile anymore, there is
> problem somewhere else, no?
>
> (Globally, I always find suspicious a kernel source that includes a system
> header)
Hi,
The wireless.h makes use of offsetof and this is defined in system
stddef.h and in include/linux/stddef.h. When we only include
linux/stddef.h it will work fine when compiled inside the kernel, but it
could cause problems when used in user space, because this would include
./include/uapi/linux/stddef.h which does not define offsetof.
I think we need the #ifdef __KERNEL__ to make this work in the kernel
and in the user space.
Hauke
On Tuesday 26 May 2020 23:02:56 CEST Hauke Mehrtens wrote:
> On 5/25/20 11:35 AM, J?r?me Pouiller wrote:
> > On Thursday 21 May 2020 22:14:22 CEST Hauke Mehrtens wrote:
> >> When compiling inside the kernel include linux/stddef.h instead of
> >> stddef.h. When I compile this header file in backports for power PC I
> >> run into a conflict with ptrdiff_t. I was unable to reproduce this in
> >> mainline kernel. I still would like to fix this problem in the kernel.
> >>
> >> Fixes: 6989310f5d43 ("wireless: Use offsetof instead of custom macro.")
> >> Signed-off-by: Hauke Mehrtens <[email protected]>
> >> ---
> >> include/uapi/linux/wireless.h | 6 +++++-
> >> 1 file changed, 5 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/include/uapi/linux/wireless.h b/include/uapi/linux/wireless.h
> >> index a2c006a364e0..24f3371ad826 100644
> >> --- a/include/uapi/linux/wireless.h
> >> +++ b/include/uapi/linux/wireless.h
> >> @@ -74,7 +74,11 @@
> >> #include <linux/socket.h> /* for "struct sockaddr" et al */
> >> #include <linux/if.h> /* for IFNAMSIZ and co... */
> >>
> >> -#include <stddef.h> /* for offsetof */
> >> +#ifdef __KERNEL__
> >> +# include <linux/stddef.h> /* for offsetof */
> >> +#else
> >> +# include <stddef.h> /* for offsetof */
> >> +#endif
> >
> > Hello,
> >
> > This patch also solves a warning I encountered when I launched sparse
> > (with make C=1):
> >
> > /usr/lib/gcc-cross/arm-linux-gnueabihf/9/include/stddef.h:406:9: warning: preprocessor token offsetof redefined
> > ./include/linux/stddef.h:17:9: this was the original definition
> >
> > However, I wonder if it useful to keep 'include <stddef.h>' when this file
> > is included from userspace. If it does not compile anymore, there is
> > problem somewhere else, no?
> >
> > (Globally, I always find suspicious a kernel source that includes a system
> > header)
> Hi,
>
> The wireless.h makes use of offsetof and this is defined in system
> stddef.h and in include/linux/stddef.h. When we only include
> linux/stddef.h it will work fine when compiled inside the kernel, but it
> could cause problems when used in user space, because this would include
> ./include/uapi/linux/stddef.h which does not define offsetof.
>
> I think we need the #ifdef __KERNEL__ to make this work in the kernel
> and in the user space.
In this case, maybe the problem should be resolved directly in
uapi/linux/stddef.h?
I have found other headers that use offsetof and may have the same problem
(currently, they do not include stddef.h. So, some of the macros do not
compile):
- include/uapi/linux/fuse.h
- include/uapi/linux/genwqe/genwqe_card.h
- include/uapi/linux/gfs2_ondisk.h
--
J?r?me Pouiller
On 5/27/20 4:03 PM, Jérôme Pouiller wrote:
> On Tuesday 26 May 2020 23:02:56 CEST Hauke Mehrtens wrote:
>> On 5/25/20 11:35 AM, Jérôme Pouiller wrote:
>>> On Thursday 21 May 2020 22:14:22 CEST Hauke Mehrtens wrote:
>>>> When compiling inside the kernel include linux/stddef.h instead of
>>>> stddef.h. When I compile this header file in backports for power PC I
>>>> run into a conflict with ptrdiff_t. I was unable to reproduce this in
>>>> mainline kernel. I still would like to fix this problem in the kernel.
>>>>
>>>> Fixes: 6989310f5d43 ("wireless: Use offsetof instead of custom macro.")
>>>> Signed-off-by: Hauke Mehrtens <[email protected]>
>>>> ---
>>>> include/uapi/linux/wireless.h | 6 +++++-
>>>> 1 file changed, 5 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/include/uapi/linux/wireless.h b/include/uapi/linux/wireless.h
>>>> index a2c006a364e0..24f3371ad826 100644
>>>> --- a/include/uapi/linux/wireless.h
>>>> +++ b/include/uapi/linux/wireless.h
>>>> @@ -74,7 +74,11 @@
>>>> #include <linux/socket.h> /* for "struct sockaddr" et al */
>>>> #include <linux/if.h> /* for IFNAMSIZ and co... */
>>>>
>>>> -#include <stddef.h> /* for offsetof */
>>>> +#ifdef __KERNEL__
>>>> +# include <linux/stddef.h> /* for offsetof */
>>>> +#else
>>>> +# include <stddef.h> /* for offsetof */
>>>> +#endif
>>>
>>> Hello,
>>>
>>> This patch also solves a warning I encountered when I launched sparse
>>> (with make C=1):
>>>
>>> /usr/lib/gcc-cross/arm-linux-gnueabihf/9/include/stddef.h:406:9: warning: preprocessor token offsetof redefined
>>> ./include/linux/stddef.h:17:9: this was the original definition
>>>
>>> However, I wonder if it useful to keep 'include <stddef.h>' when this file
>>> is included from userspace. If it does not compile anymore, there is
>>> problem somewhere else, no?
>>>
>>> (Globally, I always find suspicious a kernel source that includes a system
>>> header)
>> Hi,
>>
>> The wireless.h makes use of offsetof and this is defined in system
>> stddef.h and in include/linux/stddef.h. When we only include
>> linux/stddef.h it will work fine when compiled inside the kernel, but it
>> could cause problems when used in user space, because this would include
>> ./include/uapi/linux/stddef.h which does not define offsetof.
>>
>> I think we need the #ifdef __KERNEL__ to make this work in the kernel
>> and in the user space.
>
> In this case, maybe the problem should be resolved directly in
> uapi/linux/stddef.h?
>
> I have found other headers that use offsetof and may have the same problem
> (currently, they do not include stddef.h. So, some of the macros do not
> compile):
> - include/uapi/linux/fuse.h
> - include/uapi/linux/genwqe/genwqe_card.h
> - include/uapi/linux/gfs2_ondisk.h
>
Hi,
Would you prefer to add this to include/uapi/linux/stddef.h:
#ifndef offsetof
#define offsetof(TYPE, MEMBER) ((size_t)&((TYPE *)0)->MEMBER)
#endif
and then include linux/stddef.h in all header files which use offsetof?
include/uapi/linux/fuse.h checks for __KERNEL__ and then includes
linux/types.h or stdint.h, my initial approach would be to do this in a
similar way for stddef.h.
What is the kernel policy of including system header files like stddef.h?
Hauke