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

David Laight [off-list ref] writes:

From: Philippe Bergheaud

quoted

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.

...

quoted

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