[PATCH] selftests/fpu: fix debugfs_simple_attr.cocci warnings

[PATCH] selftests/fpu: fix debugfs_simple_attr.cocci warnings

[Julia Lawall]

From: kernel test robot <lkp@intel.com>

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().

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

Fixes: 4185b3b92792 ("selftests/fpu: Add an FPU selftest")
CC: Petteri Aimonen <jpa@git.mail.kapsi.fi>
Signed-off-by: kernel test robot <lkp@intel.com>
Signed-off-by: Julia Lawall <julia.lawall@inria.fr>
---

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   b6f96e75ae121ead54da3f58c545d68184079f90
commit: 4185b3b92792eaec5869266e594338343421ffb0 selftests/fpu: Add an FPU selftest
:::::: branch date: 2 hours ago
:::::: commit date: 4 months ago

I don't know much about this issue, but I'm passing the warning along.
The original commit of the semantic patch contains some more information:

    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.

 test_fpu.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

--- a/lib/test_fpu.c
+++ b/lib/test_fpu.c
@@ -63,7 +63,7 @@ static int test_fpu_get(void *data, u64
 	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;
 }

[tip: x86/misc] selftests/fpu: Fix debugfs_simple_attr.cocci warning

[tip-bot2 for kernel test robot]

The following commit has been merged into the x86/misc branch of tip:

Commit-ID:     443121b3ebb9025fd99ff11851d3537cb756d456
Gitweb:        https://git.kernel.org/tip/443121b3ebb9025fd99ff11851d3537cb756d456
Author:        kernel test robot <lkp@intel.com>
AuthorDate:    Sun, 25 Oct 2020 11:20:04 +01:00
Committer:     Borislav Petkov <bp@suse.de>
CommitterDate: Mon, 18 Jan 2021 11:03:26 +01:00

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: 4185b3b92792 ("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 | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/lib/test_fpu.c b/lib/test_fpu.c
index c33764a..e82db19 100644
--- a/lib/test_fpu.c
+++ b/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;
 }