selftests/vm: use a common gup_test.h

Avoid the need to copy-paste the gup_test ioctl commands and the struct
gup_test definition, between the kernel and the user space application, by
providing a new header file for these.  This allows easier and safer
adding of new ioctl calls, as well as reducing the overall line count.

Details: The header file has to be able to compile independently, because
of the arguably unfortunate way that the Makefile is written: the Makefile
tries to build all of its prerequisites, when really it should be only
building the .c files, and leaving the other prerequisites (LOCAL_HDRS) as
pure dependencies.

That Makefile limitation is probably not worth fixing, but it explains why
one of the includes had to be moved into the new header file.

Also: simplify the ioctl struct (struct gup_test), by deleting the unused
__expansion[10] field.  This sort of thing is what you might see in a
stable ABI, but this low-level, kernel-developer-oriented selftests/vm
system is very much not subject to ABI stability.  So "expansion" and
"reserved" fields are unnecessary here.

Link: https://lkml.kernel.org/r/20201026064021.3545418-3-jhubbard@nvidia.com
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 1 insertions, 16 deletions

diff --git a/mm/gup_test.c b/mm/gup_test.c
index 59472ea6aa39..4c2d70d88f24 100644
--- a/mm/gup_test.c
+++ b/mm/gup_test.c
@@ -4,22 +4,7 @@
 #include <linux/uaccess.h>
 #include <linux/ktime.h>
 #include <linux/debugfs.h>
-
-#define GUP_FAST_BENCHMARK	_IOWR('g', 1, struct gup_test)
-#define GUP_BENCHMARK		_IOWR('g', 2, struct gup_test)
-#define PIN_FAST_BENCHMARK	_IOWR('g', 3, struct gup_test)
-#define PIN_BENCHMARK		_IOWR('g', 4, struct gup_test)
-#define PIN_LONGTERM_BENCHMARK	_IOWR('g', 5, struct gup_test)
-
-struct gup_test {
-	__u64 get_delta_usec;
-	__u64 put_delta_usec;
-	__u64 addr;
-	__u64 size;
-	__u32 nr_pages_per_call;
-	__u32 flags;
-	__u64 expansion[10];	/* For future use */
-};
+#include "gup_test.h"
 
 static void put_back_pages(unsigned int cmd, struct page **pages,
 			   unsigned long nr_pages)