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debugfs: add debugfs_lookup_and_remove() 

There is a very common pattern of using
debugfs_remove(debufs_lookup(..)) which results in a dentry leak of the
dentry that was looked up.  Instead of having to open-code the correct
pattern of calling dput() on the dentry, create
debugfs_lookup_and_remove() to handle this pattern automatically and
properly without any memory leaks.

Cc: stable <stable@kernel.org>
Reported-by: Kuyo Chang <kuyo.chang@mediatek.com>
Tested-by: Kuyo Chang <kuyo.chang@mediatek.com>
Link: https://lore.kernel.org/r/YxIaQ8cSinDR881k@kroah.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Greg Kroah-Hartman 2022-09-02 16:59:15 +02:00
parent 5666a274a6
commit dec9b2f1e0
2 changed files with 28 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

22
fs/debugfs/inode.c
View File

@ -744,6 +744,28 @@ void debugfs_remove(struct dentry *dentry)
}
EXPORT_SYMBOL_GPL(debugfs_remove);
/**
* debugfs_lookup_and_remove - lookup a directory or file and recursively remove it
* @name: a pointer to a string containing the name of the item to look up.
* @parent: a pointer to the parent dentry of the item.
*
* This is the equlivant of doing something like
* debugfs_remove(debugfs_lookup(..)) but with the proper reference counting
* handled for the directory being looked up.
*/
void debugfs_lookup_and_remove(const char *name, struct dentry *parent)
{
struct dentry *dentry;
dentry = debugfs_lookup(name, parent);
if (!dentry)
return;
debugfs_remove(dentry);
dput(dentry);
}
EXPORT_SYMBOL_GPL(debugfs_lookup_and_remove);
/**
* debugfs_rename - rename a file/directory in the debugfs filesystem
* @old_dir: a pointer to the parent dentry for the renamed object. This

6
include/linux/debugfs.h
View File

@ -91,6 +91,8 @@ struct dentry *debugfs_create_automount(const char *name,
void debugfs_remove(struct dentry *dentry);
#define debugfs_remove_recursive debugfs_remove
void debugfs_lookup_and_remove(const char *name, struct dentry *parent);
const struct file_operations *debugfs_real_fops(const struct file *filp);
int debugfs_file_get(struct dentry *dentry);
@ -225,6 +227,10 @@ static inline void debugfs_remove(struct dentry *dentry)
static inline void debugfs_remove_recursive(struct dentry *dentry)
{ }
static inline void debugfs_lookup_and_remove(const char *name,
struct dentry *parent)
{ }
const struct file_operations *debugfs_real_fops(const struct file *filp);
static inline int debugfs_file_get(struct dentry *dentry)