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authorNicolai Stange <nicstange@gmail.com>2016-03-22 16:11:15 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2016-04-13 00:14:21 +0300
commitc64688081490321f2d23a292ef24e60bb321f3f1 (patch)
treea2fb5072922a286d0161b9125ca7c04ecf79fa0b /include/linux/debugfs.h
parent49d200deaa680501f19a247b1fffb29301e51d2b (diff)
downloadlinux-c64688081490321f2d23a292ef24e60bb321f3f1.tar.xz
debugfs: add support for self-protecting attribute file fops
In order to protect them against file removal issues, debugfs_create_file() creates a lifetime managing proxy around each struct file_operations handed in. In cases where this struct file_operations is able to manage file lifetime by itself already, the proxy created by debugfs is a waste of resources. The most common class of struct file_operations given to debugfs are those defined by means of the DEFINE_SIMPLE_ATTRIBUTE() macro. Introduce a DEFINE_DEBUGFS_ATTRIBUTE() macro to allow any struct file_operations of this class to be easily made file lifetime aware and thus, to be operated unproxied. Specifically, introduce debugfs_attr_read() and debugfs_attr_write() which wrap simple_attr_read() and simple_attr_write() under the protection of a debugfs_use_file_start()/debugfs_use_file_finish() pair. Make DEFINE_DEBUGFS_ATTRIBUTE() set the defined struct file_operations' ->read() and ->write() members to these wrappers. Export debugfs_create_file_unsafe() in order to allow debugfs users to create their files in non-proxying operation mode. Signed-off-by: Nicolai Stange <nicstange@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'include/linux/debugfs.h')
-rw-r--r--include/linux/debugfs.h26
1 files changed, 26 insertions, 0 deletions
diff --git a/include/linux/debugfs.h b/include/linux/debugfs.h
index a63e6ea3321c..1438e2322d5c 100644
--- a/include/linux/debugfs.h
+++ b/include/linux/debugfs.h
@@ -50,6 +50,9 @@ extern struct srcu_struct debugfs_srcu;
struct dentry *debugfs_create_file(const char *name, umode_t mode,
struct dentry *parent, void *data,
const struct file_operations *fops);
+struct dentry *debugfs_create_file_unsafe(const char *name, umode_t mode,
+ struct dentry *parent, void *data,
+ const struct file_operations *fops);
struct dentry *debugfs_create_file_size(const char *name, umode_t mode,
struct dentry *parent, void *data,
@@ -74,6 +77,26 @@ int debugfs_use_file_start(const struct dentry *dentry, int *srcu_idx)
void debugfs_use_file_finish(int srcu_idx) __releases(&debugfs_srcu);
+ssize_t debugfs_attr_read(struct file *file, char __user *buf,
+ size_t len, loff_t *ppos);
+ssize_t debugfs_attr_write(struct file *file, const char __user *buf,
+ size_t len, loff_t *ppos);
+
+#define DEFINE_DEBUGFS_ATTRIBUTE(__fops, __get, __set, __fmt) \
+static int __fops ## _open(struct inode *inode, struct file *file) \
+{ \
+ __simple_attr_check_format(__fmt, 0ull); \
+ return simple_attr_open(inode, file, __get, __set, __fmt); \
+} \
+static const struct file_operations __fops = { \
+ .owner = THIS_MODULE, \
+ .open = __fops ## _open, \
+ .release = simple_attr_release, \
+ .read = debugfs_attr_read, \
+ .write = debugfs_attr_write, \
+ .llseek = generic_file_llseek, \
+}
+
struct dentry *debugfs_rename(struct dentry *old_dir, struct dentry *old_dentry,
struct dentry *new_dir, const char *new_name);
@@ -193,6 +216,9 @@ static inline void debugfs_use_file_finish(int srcu_idx)
__releases(&debugfs_srcu)
{ }
+#define DEFINE_DEBUGFS_ATTRIBUTE(__fops, __get, __set, __fmt) \
+ static const struct file_operations __fops = { 0 }
+
static inline struct dentry *debugfs_rename(struct dentry *old_dir, struct dentry *old_dentry,
struct dentry *new_dir, char *new_name)
{