linux-kernel - [PATCH 1/2] debugfs: Remove redundant access mode checks

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Message-ID: <20251120102222.18371-2-dev@null.aaront.org>
Date: Thu, 20 Nov 2025 10:26:32 +0000
From: Aaron Thompson <dev@...ont.org>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	"Rafael J. Wysocki" <rafael@...nel.org>,
	Danilo Krummrich <dakr@...nel.org>
Cc: Jonathan Corbet <corbet@....net>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-doc@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Aaron Thompson <dev@...ont.org>
Subject: [PATCH 1/2] debugfs: Remove redundant access mode checks

debugfs_get_tree() can only be called if debugfs itself calls
simple_pin_fs() or register_filesystem(), and those call paths also
check the access mode.

debugfs_start_creating() checks the access mode so the checks in the
debugfs_create_* functions are unnecessary.

An upcoming change will affect debugfs_allow, so doing this cleanup
first will make that change simpler.

Signed-off-by: Aaron Thompson <dev@...ont.org>
---
 fs/debugfs/inode.c | 18 ------------------
 1 file changed, 18 deletions(-)

diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c
index 661a99a7dfbe..b6e401c46b6b 100644
--- a/fs/debugfs/inode.c
+++ b/fs/debugfs/inode.c
@@ -287,9 +287,6 @@ static int debugfs_get_tree(struct fs_context *fc)
 {
 	int err;
 
-	if (!(debugfs_allow & DEBUGFS_ALLOW_API))
-		return -EPERM;
-
 	err = get_tree_single(fc, debugfs_fill_super);
 	if (err)
 		return err;
@@ -434,11 +431,6 @@ static struct dentry *__debugfs_create_file(const char *name, umode_t mode,
 	if (IS_ERR(dentry))
 		return dentry;
 
-	if (!(debugfs_allow & DEBUGFS_ALLOW_API)) {
-		failed_creating(dentry);
-		return ERR_PTR(-EPERM);
-	}
-
 	inode = debugfs_get_inode(dentry->d_sb);
 	if (unlikely(!inode)) {
 		pr_err("out of free dentries, can not create file '%s'\n",
@@ -584,11 +576,6 @@ struct dentry *debugfs_create_dir(const char *name, struct dentry *parent)
 	if (IS_ERR(dentry))
 		return dentry;
 
-	if (!(debugfs_allow & DEBUGFS_ALLOW_API)) {
-		failed_creating(dentry);
-		return ERR_PTR(-EPERM);
-	}
-
 	inode = debugfs_get_inode(dentry->d_sb);
 	if (unlikely(!inode)) {
 		pr_err("out of free dentries, can not create directory '%s'\n",
@@ -631,11 +618,6 @@ struct dentry *debugfs_create_automount(const char *name,
 	if (IS_ERR(dentry))
 		return dentry;
 
-	if (!(debugfs_allow & DEBUGFS_ALLOW_API)) {
-		failed_creating(dentry);
-		return ERR_PTR(-EPERM);
-	}
-
 	inode = debugfs_get_inode(dentry->d_sb);
 	if (unlikely(!inode)) {
 		pr_err("out of free dentries, can not create automount '%s'\n",
-- 
2.47.3