Commit c9afbec2 authored by Nicolai Stange's avatar Nicolai Stange Committed by Greg Kroah-Hartman

debugfs: purge obsolete SRCU based removal protection

Purge the SRCU based file removal race protection in favour of the new,
refcount based debugfs_file_get()/debugfs_file_put() API.

Fixes: 49d200de ("debugfs: prevent access to removed files' private data")
Signed-off-by: default avatarNicolai Stange <nicstange@gmail.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 7cda7b8f
...@@ -22,7 +22,6 @@ ...@@ -22,7 +22,6 @@
#include <linux/slab.h> #include <linux/slab.h>
#include <linux/atomic.h> #include <linux/atomic.h>
#include <linux/device.h> #include <linux/device.h>
#include <linux/srcu.h>
#include <asm/poll.h> #include <asm/poll.h>
#include "internal.h" #include "internal.h"
...@@ -48,53 +47,6 @@ const struct file_operations debugfs_noop_file_operations = { ...@@ -48,53 +47,6 @@ const struct file_operations debugfs_noop_file_operations = {
.llseek = noop_llseek, .llseek = noop_llseek,
}; };
/**
* debugfs_use_file_start - mark the beginning of file data access
* @dentry: the dentry object whose data is being accessed.
* @srcu_idx: a pointer to some memory to store a SRCU index in.
*
* Up to a matching call to debugfs_use_file_finish(), any
* successive call into the file removing functions debugfs_remove()
* and debugfs_remove_recursive() will block. Since associated private
* file data may only get freed after a successful return of any of
* the removal functions, you may safely access it after a successful
* call to debugfs_use_file_start() without worrying about
* lifetime issues.
*
* If -%EIO is returned, the file has already been removed and thus,
* it is not safe to access any of its data. If, on the other hand,
* it is allowed to access the file data, zero is returned.
*
* Regardless of the return code, any call to
* debugfs_use_file_start() must be followed by a matching call
* to debugfs_use_file_finish().
*/
int debugfs_use_file_start(const struct dentry *dentry, int *srcu_idx)
__acquires(&debugfs_srcu)
{
*srcu_idx = srcu_read_lock(&debugfs_srcu);
barrier();
if (d_unlinked(dentry))
return -EIO;
return 0;
}
EXPORT_SYMBOL_GPL(debugfs_use_file_start);
/**
* debugfs_use_file_finish - mark the end of file data access
* @srcu_idx: the SRCU index "created" by a former call to
* debugfs_use_file_start().
*
* Allow any ongoing concurrent call into debugfs_remove() or
* debugfs_remove_recursive() blocked by a former call to
* debugfs_use_file_start() to proceed and return to its caller.
*/
void debugfs_use_file_finish(int srcu_idx) __releases(&debugfs_srcu)
{
srcu_read_unlock(&debugfs_srcu, srcu_idx);
}
EXPORT_SYMBOL_GPL(debugfs_use_file_finish);
#define F_DENTRY(filp) ((filp)->f_path.dentry) #define F_DENTRY(filp) ((filp)->f_path.dentry)
const struct file_operations *debugfs_real_fops(const struct file *filp) const struct file_operations *debugfs_real_fops(const struct file *filp)
......
...@@ -27,14 +27,11 @@ ...@@ -27,14 +27,11 @@
#include <linux/parser.h> #include <linux/parser.h>
#include <linux/magic.h> #include <linux/magic.h>
#include <linux/slab.h> #include <linux/slab.h>
#include <linux/srcu.h>
#include "internal.h" #include "internal.h"
#define DEBUGFS_DEFAULT_MODE 0700 #define DEBUGFS_DEFAULT_MODE 0700
DEFINE_SRCU(debugfs_srcu);
static struct vfsmount *debugfs_mount; static struct vfsmount *debugfs_mount;
static int debugfs_mount_count; static int debugfs_mount_count;
static bool debugfs_registered; static bool debugfs_registered;
...@@ -693,8 +690,6 @@ void debugfs_remove(struct dentry *dentry) ...@@ -693,8 +690,6 @@ void debugfs_remove(struct dentry *dentry)
inode_unlock(d_inode(parent)); inode_unlock(d_inode(parent));
if (!ret) if (!ret)
simple_release_fs(&debugfs_mount, &debugfs_mount_count); simple_release_fs(&debugfs_mount, &debugfs_mount_count);
synchronize_srcu(&debugfs_srcu);
} }
EXPORT_SYMBOL_GPL(debugfs_remove); EXPORT_SYMBOL_GPL(debugfs_remove);
...@@ -768,8 +763,6 @@ void debugfs_remove_recursive(struct dentry *dentry) ...@@ -768,8 +763,6 @@ void debugfs_remove_recursive(struct dentry *dentry)
if (!__debugfs_remove(child, parent)) if (!__debugfs_remove(child, parent))
simple_release_fs(&debugfs_mount, &debugfs_mount_count); simple_release_fs(&debugfs_mount, &debugfs_mount_count);
inode_unlock(d_inode(parent)); inode_unlock(d_inode(parent));
synchronize_srcu(&debugfs_srcu);
} }
EXPORT_SYMBOL_GPL(debugfs_remove_recursive); EXPORT_SYMBOL_GPL(debugfs_remove_recursive);
......
...@@ -23,7 +23,6 @@ ...@@ -23,7 +23,6 @@
struct device; struct device;
struct file_operations; struct file_operations;
struct srcu_struct;
struct debugfs_blob_wrapper { struct debugfs_blob_wrapper {
void *data; void *data;
...@@ -43,8 +42,6 @@ struct debugfs_regset32 { ...@@ -43,8 +42,6 @@ struct debugfs_regset32 {
extern struct dentry *arch_debugfs_dir; extern struct dentry *arch_debugfs_dir;
extern struct srcu_struct debugfs_srcu;
#define DEFINE_DEBUGFS_ATTRIBUTE(__fops, __get, __set, __fmt) \ #define DEFINE_DEBUGFS_ATTRIBUTE(__fops, __get, __set, __fmt) \
static int __fops ## _open(struct inode *inode, struct file *file) \ static int __fops ## _open(struct inode *inode, struct file *file) \
{ \ { \
...@@ -90,11 +87,6 @@ struct dentry *debugfs_create_automount(const char *name, ...@@ -90,11 +87,6 @@ struct dentry *debugfs_create_automount(const char *name,
void debugfs_remove(struct dentry *dentry); void debugfs_remove(struct dentry *dentry);
void debugfs_remove_recursive(struct dentry *dentry); void debugfs_remove_recursive(struct dentry *dentry);
int debugfs_use_file_start(const struct dentry *dentry, int *srcu_idx)
__acquires(&debugfs_srcu);
void debugfs_use_file_finish(int srcu_idx) __releases(&debugfs_srcu);
const struct file_operations *debugfs_real_fops(const struct file *filp); const struct file_operations *debugfs_real_fops(const struct file *filp);
int debugfs_file_get(struct dentry *dentry); int debugfs_file_get(struct dentry *dentry);
...@@ -227,17 +219,6 @@ static inline void debugfs_remove(struct dentry *dentry) ...@@ -227,17 +219,6 @@ static inline void debugfs_remove(struct dentry *dentry)
static inline void debugfs_remove_recursive(struct dentry *dentry) static inline void debugfs_remove_recursive(struct dentry *dentry)
{ } { }
static inline int debugfs_use_file_start(const struct dentry *dentry,
int *srcu_idx)
__acquires(&debugfs_srcu)
{
return 0;
}
static inline void debugfs_use_file_finish(int srcu_idx)
__releases(&debugfs_srcu)
{ }
static inline int debugfs_file_get(struct dentry *dentry) static inline int debugfs_file_get(struct dentry *dentry)
{ {
return 0; return 0;
......
...@@ -280,7 +280,6 @@ config PAGE_OWNER ...@@ -280,7 +280,6 @@ config PAGE_OWNER
config DEBUG_FS config DEBUG_FS
bool "Debug Filesystem" bool "Debug Filesystem"
select SRCU
help help
debugfs is a virtual file system that kernel developers use to put debugfs is a virtual file system that kernel developers use to put
debugging files into. Enable this option to be able to read and debugging files into. Enable this option to be able to read and
......
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