[PATCH] cxl: Use fixed width predefined types in data structure.

[PATCH] cxl: Use fixed width predefined types in data structure.

[Philippe Bergheaud]

This patch fixes a regression introduced by commit b810253.
It substitutes the type __u8 to u8 in the uapi header cxl.h,
because the latter is not always defined in userland build
environments, in particular when cross-compiling libcxl on
x86_64 linux machines (RHEL6.7 and Ubuntu 16.04).

It also makes the definition of cxl_event_afu_driver_reserved
more consistent with the other definitions in the header file.

Signed-off-by: Philippe Bergheaud <felix@linux.vnet.ibm.com>
---
 include/uapi/misc/cxl.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/uapi/misc/cxl.h b/include/uapi/misc/cxl.h
index cbae529..180d526 100644
--- a/include/uapi/misc/cxl.h
+++ b/include/uapi/misc/cxl.h
@@ -136,8 +136,8 @@ struct cxl_event_afu_driver_reserved {
 	 *
 	 * Of course the contents will be ABI, but that's up the AFU driver.
 	 */
-	size_t data_size;
-	u8 data[];
+	__u32 data_size;
+	__u8 data[];
 };
 
 struct cxl_event {
-- 
2.8.0

RE: [PATCH] cxl: Use fixed width predefined types in data structure.

[David Laight]

From: Philippe Bergheaud
> Sent: 04 August 2016 14:56
> This patch fixes a regression introduced by commit b810253.
> It substitutes the type __u8 to u8 in the uapi header cxl.h,
> because the latter is not always defined in userland build
> environments, in particular when cross-compiling libcxl on
> x86_64 linux machines (RHEL6.7 and Ubuntu 16.04).
>=20
> It also makes the definition of cxl_event_afu_driver_reserved
> more consistent with the other definitions in the header file.
...
> diff --git a/include/uapi/misc/cxl.h b/include/uapi/misc/cxl.h
> index cbae529..180d526 100644
> --- a/include/uapi/misc/cxl.h
> +++ b/include/uapi/misc/cxl.h
> @@ -136,8 +136,8 @@ struct cxl_event_afu_driver_reserved {
>  	 *
>  	 * Of course the contents will be ABI, but that's up the AFU driver.
>  	 */
> -	size_t data_size;
> -	u8 data[];
> +	__u32 data_size;
> +	__u8 data[];
>  };

You've just changed 'data_size' from 64bit to 32bit (on 64bit systems).
This isn't mentioned in the commit message and changes the API.

I've NFI what it need to be...

	David

RE: [PATCH] cxl: Use fixed width predefined types in data structure.

[Michael Ellerman]

David Laight <David.Laight@ACULAB.COM> writes:

> From: Philippe Bergheaud
>> Sent: 04 August 2016 14:56
>> This patch fixes a regression introduced by commit b810253.
>> It substitutes the type __u8 to u8 in the uapi header cxl.h,
>> because the latter is not always defined in userland build
>> environments, in particular when cross-compiling libcxl on
>> x86_64 linux machines (RHEL6.7 and Ubuntu 16.04).
>> 
>> It also makes the definition of cxl_event_afu_driver_reserved
>> more consistent with the other definitions in the header file.
> ...
>> diff --git a/include/uapi/misc/cxl.h b/include/uapi/misc/cxl.h
>> index cbae529..180d526 100644
>> --- a/include/uapi/misc/cxl.h
>> +++ b/include/uapi/misc/cxl.h
>> @@ -136,8 +136,8 @@ struct cxl_event_afu_driver_reserved {
>>  	 *
>>  	 * Of course the contents will be ABI, but that's up the AFU driver.
>>  	 */
>> -	size_t data_size;
>> -	u8 data[];
>> +	__u32 data_size;
>> +	__u8 data[];
>>  };
>
> You've just changed 'data_size' from 64bit to 32bit (on 64bit systems).
> This isn't mentioned in the commit message and changes the API.

Yeah that's pretty fishy.

In practice I suspect there aren't thousands of users of that API, the
commit is only a month old, so we can probably still change it. But
please call it out in the change log.

cheers