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Subject[PATCH next 2/3] debugfs: introduce debugfs_create_single[,_data]
Date
Like proc_create_single[,_data] in procfs, introduce a similar
debugfs_create_single[,_data] function, which could drastically
reduces the boilerplate code.

Rename debugfs_devm_entry to debugfs_entry, and reuse debugfs_entry_ops
code. The struct debugfs_entry instance is dynamically allocated
and taken as data in debugfs_create_single_data, which need to be
freed when calling debugfs_remove, using lowest bit of inode->i_private
to distinguish it.

Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
---
fs/debugfs/file.c | 58 ++++++++++++++++++++++++++++++++++-------
fs/debugfs/inode.c | 4 +++
include/linux/debugfs.h | 18 +++++++++++++
3 files changed, 70 insertions(+), 10 deletions(-)

diff --git a/fs/debugfs/file.c b/fs/debugfs/file.c
index 38c17a99eb17..68f0c4b19bef 100644
--- a/fs/debugfs/file.c
+++ b/fs/debugfs/file.c
@@ -1106,21 +1106,24 @@ EXPORT_SYMBOL_GPL(debugfs_create_regset32);

#endif /* CONFIG_HAS_IOMEM */

-struct debugfs_devm_entry {
+struct debugfs_entry {
int (*read)(struct seq_file *seq, void *data);
- struct device *dev;
+ void *data;
};

-static int debugfs_devm_entry_open(struct inode *inode, struct file *f)
+static int debugfs_entry_open(struct inode *inode, struct file *f)
{
- struct debugfs_devm_entry *entry = inode->i_private;
+ struct debugfs_entry *entry = inode->i_private;

- return single_open(f, entry->read, entry->dev);
+ if (debugfs_test_lowest_bit(entry))
+ entry = debugfs_clear_lowest_bit(entry);
+
+ return single_open(f, entry->read, entry->data);
}

-static const struct file_operations debugfs_devm_entry_ops = {
+static const struct file_operations debugfs_entry_ops = {
.owner = THIS_MODULE,
- .open = debugfs_devm_entry_open,
+ .open = debugfs_entry_open,
.release = single_release,
.read = seq_read,
.llseek = seq_lseek
@@ -1141,7 +1144,7 @@ struct dentry *debugfs_create_devm_seqfile(struct device *dev, const char *name,
int (*read_fn)(struct seq_file *s,
void *data))
{
- struct debugfs_devm_entry *entry;
+ struct debugfs_entry *entry;

if (IS_ERR(parent))
return ERR_PTR(-ENOENT);
@@ -1151,10 +1154,45 @@ struct dentry *debugfs_create_devm_seqfile(struct device *dev, const char *name,
return ERR_PTR(-ENOMEM);

entry->read = read_fn;
- entry->dev = dev;
+ entry->data = dev;

return debugfs_create_file(name, S_IRUGO, parent, entry,
- &debugfs_devm_entry_ops);
+ &debugfs_entry_ops);
}
EXPORT_SYMBOL_GPL(debugfs_create_devm_seqfile);

+/**
+ * debugfs_create_single_data - create a file in the debugfs filesystem
+ * @name: a pointer to a string containing the name of the file to create.
+ * @mode: the permission that the file should have.
+ * @parent: a pointer to the parent dentry for this file. This should be a
+ * directory dentry if set. If this parameter is NULL, then the
+ * file will be created in the root of the debugfs filesystem.
+ * @data: a pointer to something that the caller will want to get to later
+ * on. The inode.i_private pointer will point to this value on
+ * the open() call.
+ * @read_fn: function pointer called to print the seq_file content.
+ *
+ * This function creates a file in debugfs with the extra data and a seq_file
+ * show callback.
+ */
+struct dentry *debugfs_create_single_data(const char *name, umode_t mode,
+ struct dentry *parent, void *data,
+ int (*read_fn)(struct seq_file *s,
+ void *data))
+{
+ struct debugfs_entry *entry;
+
+ entry = kzalloc(sizeof(*entry), GFP_KERNEL);
+ if (!entry)
+ return ERR_PTR(-ENOMEM);
+
+ entry->read = read_fn;
+ entry->data = data;
+
+ entry = debugfs_set_lowest_bit(entry);
+
+ return debugfs_create_file(name, mode, parent, entry,
+ &debugfs_entry_ops);
+}
+EXPORT_SYMBOL_GPL(debugfs_create_single_data);
diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c
index cc24e97686d0..58cbb7af2a55 100644
--- a/fs/debugfs/inode.c
+++ b/fs/debugfs/inode.c
@@ -197,6 +197,10 @@ static void debugfs_free_inode(struct inode *inode)
{
if (S_ISLNK(inode->i_mode))
kfree(inode->i_link);
+
+ if (debugfs_test_lowest_bit(inode->i_private))
+ kfree(debugfs_clear_lowest_bit(inode->i_private));
+
free_inode_nonrcu(inode);
}

diff --git a/include/linux/debugfs.h b/include/linux/debugfs.h
index bf9b6cafa4c2..82171f183e93 100644
--- a/include/linux/debugfs.h
+++ b/include/linux/debugfs.h
@@ -142,6 +142,11 @@ struct dentry *debugfs_create_devm_seqfile(struct device *dev, const char *name,
int (*read_fn)(struct seq_file *s,
void *data));

+struct dentry *debugfs_create_single_data(const char *name, umode_t mode,
+ struct dentry *parent, void *data,
+ int (*read_fn)(struct seq_file *s,
+ void *data));
+
bool debugfs_initialized(void);

ssize_t debugfs_read_file_bool(struct file *file, char __user *user_buf,
@@ -336,6 +341,16 @@ static inline struct dentry *debugfs_create_devm_seqfile(struct device *dev,
return ERR_PTR(-ENODEV);
}

+static inline struct dentry *debugfs_create_single_data(const char *name,
+ umode_t mode,
+ struct dentry *parent,
+ void *data,
+ int (*read_fn)(struct seq_file *s,
+ void *data))
+{
+ return ERR_PTR(-ENODEV);
+}
+
static inline ssize_t debugfs_read_file_bool(struct file *file,
char __user *user_buf,
size_t count, loff_t *ppos)
@@ -352,6 +367,9 @@ static inline ssize_t debugfs_write_file_bool(struct file *file,

#endif

+#define debugfs_create_single(name, mode, parent, read) \
+ debugfs_create_single_data(name, mode, parent, NULL, read)
+
/**
* debugfs_create_xul - create a debugfs file that is used to read and write an
* unsigned long value, formatted in hexadecimal
--
2.20.1
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