selftests/fpu: Fix debugfs_simple_attr.cocci warning

lib/test_fpu.c:66:0-23: WARNING: test_fpu_fops should be defined with DEFINE_DEBUGFS_ATTRIBUTE

 Use DEFINE_DEBUGFS_ATTRIBUTE rather than DEFINE_SIMPLE_ATTRIBUTE
 for debugfs files.

Semantic patch information:

 Rationale: DEFINE_SIMPLE_ATTRIBUTE + debugfs_create_file()
 imposes some significant overhead as compared to
 DEFINE_DEBUGFS_ATTRIBUTE + debugfs_create_file_unsafe().

In order to protect against file removal races, debugfs files created
via debugfs_create_file() now get wrapped by a struct file_operations
at their opening.

If the original struct file_operations are known to be safe against
removal races by themselves already, the proxy creation may be bypassed
by creating the files through debugfs_create_file_unsafe().

In order to help debugfs users who use the common
DEFINE_SIMPLE_ATTRIBUTE() + debugfs_create_file() idiom to
transition to removal safe struct file_operations, the helper macro
DEFINE_DEBUGFS_ATTRIBUTE() has been introduced.

Thus, the preferred strategy is to use
  DEFINE_DEBUGFS_ATTRIBUTE() + debugfs_create_file_unsafe()
now.

Generated by: scripts/coccinelle/api/debugfs/debugfs_simple_attr.cocci

Fixes: 4185b3b9 ("selftests/fpu: Add an FPU selftest")
Signed-off-by: kernel test robot <lkp@intel.com>
Signed-off-by: Julia Lawall <julia.lawall@inria.fr>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/alpine.DEB.2.22.394.2010251117180.2714@hadrien

lib/test_fpu.c

@@ -63,7 +63,7 @@ static int test_fpu_get(void *data, u64 *val)
 	return status;
 }
 
-DEFINE_SIMPLE_ATTRIBUTE(test_fpu_fops, test_fpu_get, NULL, "%lld\n");
+DEFINE_DEBUGFS_ATTRIBUTE(test_fpu_fops, test_fpu_get, NULL, "%lld\n");
 static struct dentry *selftest_dir;
 
 static int __init test_fpu_init(void)
@@ -72,8 +72,8 @@ static int __init test_fpu_init(void)
 	if (!selftest_dir)
 		return -ENOMEM;
 
-	debugfs_create_file("test_fpu", 0444, selftest_dir, NULL,
-			    &test_fpu_fops);
+	debugfs_create_file_unsafe("test_fpu", 0444, selftest_dir, NULL,
+				   &test_fpu_fops);
 
 	return 0;
 }