[PATCH] selftests: cgroup: give the O_TMPFILE open in get_temp_fd() a mode

[Eva Kurchatova <eva.kurchatova@virtuozzo.com>]

O_TMPFILE, like O_CREAT, needs the third argument. Without it glibc
refuses the call at compile time as soon as fortification is on:

  In function 'open',
      inlined from 'get_temp_fd' at test_memcontrol.c:33:9:
  /usr/include/bits/fcntl2.h:52:11: error: call to '__open_missing_mode'
    declared with attribute error: open with O_CREAT or O_TMPFILE in
    second argument needs 3 arguments

The fortify checks take effect only once the compiler optimises, and
cgroup/Makefile builds with "-Wall -pthread" alone, so this goes
unnoticed in a plain build. Building the tests with the flags
distributions commonly use, -O2 -D_FORTIFY_SOURCE=3, loses
test_memcontrol entirely.

Fixes: 84092dbcf901 ("selftests: cgroup: add memory controller self-tests")
Signed-off-by: Eva Kurchatova <eva.kurchatova@virtuozzo.com>
---
 tools/testing/selftests/cgroup/test_memcontrol.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/testing/selftests/cgroup/test_memcontrol.c b/tools/testing/selftests/cgroup/test_memcontrol.c
index 3a84d068fbf3..0ed82347044e 100644
--- a/tools/testing/selftests/cgroup/test_memcontrol.c
+++ b/tools/testing/selftests/cgroup/test_memcontrol.c
@@ -30,7 +30,7 @@ static int page_size;
 
 int get_temp_fd(void)
 {
-	return open(".", O_TMPFILE | O_RDWR | O_EXCL);
+	return open(".", O_TMPFILE | O_RDWR | O_EXCL, 0600);
 }
 
 int alloc_pagecache(int fd, size_t size)
-- 
2.55.0