linux-kernel - [tip: x86/misc] selftests/fpu: Fix debugfs_simple

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Date:   Mon, 18 Jan 2021 11:50:11 -0000
From:   "tip-bot2 for kernel test robot" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     kernel test robot <lkp@...el.com>,
        Julia Lawall <julia.lawall@...ia.fr>,
        Borislav Petkov <bp@...e.de>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [tip: x86/misc] selftests/fpu: Fix debugfs_simple_attr.cocci warning

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@...el.com>
AuthorDate:    Sun, 25 Oct 2020 11:20:04 +01:00
Committer:     Borislav Petkov <bp@...e.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@...el.com>
Signed-off-by: Julia Lawall <julia.lawall@...ia.fr>
Signed-off-by: Borislav Petkov <bp@...e.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;
 }