The patch titled
doc: add documentation for debugfs
has been added to the -mm tree. Its filename is
doc-add-documentation-for-debugfs.patch
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------------------------------------------------------
Subject: doc: add documentation for debugfs
From: Shen Feng <shen@xxxxxxxxxxxxxx>
debugfs is used as a virtual filesystem devoted to debugging information.
But it's not documented in Documentation/filesystems. Add one for it.
The content is mainly from http://lwn.net/Articles/115405/
Signed-off-by: Shen Feng <shen@xxxxxxxxxxxxxx>
Cc: Greg KH <greg@xxxxxxxxx>
Cc: Jonathan Corbet <corbet@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
Documentation/filesystems/debugfs.txt | 51 ++++++++++++++++++++++++
1 file changed, 51 insertions(+)
diff -puN /dev/null Documentation/filesystems/debugfs.txt
--- /dev/null
+++ a/Documentation/filesystems/debugfs.txt
@@ -0,0 +1,51 @@
+ Debugfs - a virtual filesystem devoted to debugging information
+
+Debugfs is a virtual filesystem devoted to debugging information. Debugfs is
+intended to be a relatively easy and lightweight subsystem which gracefully
+disappears when configured out of the kernel.
+
+Traditionally debugfs is supposed to be mounted at /sys/kernel/debug with the
+following command:
+
+ # mount -t debugfs none /sys/kernel/debug/
+
+A developer wishing to use debugfs starts by creating a directory within the
+filesystem:
+
+ struct dentry *debugfs_create_dir(const char *name,
+ struct dentry *parent);
+
+The parent argument will usually be NULL, causing the directory to be created
+in the debugfs root. If debugfs is not configured into the system, the return
+value is -ENODEV; a NULL return, instead, indicates some other sort of error.
+
+The general-purpose function for creating a file in debugfs is:
+
+ struct dentry *debugfs_create_file(const char *name, mode_t mode,
+ struct dentry *parent, void *data,
+ struct file_operations *fops);
+
+The structure pointed to by fops should, of course, contain pointers to the
+functions which implement the actual operations on the file. In many cases,
+most of those functions can be the helpers provided by seq_file, making the
+task of exporting a file easy.
+
+Some additional helpers have been provided to make exporting a single value as
+easy as possible:
+
+ struct dentry *debugfs_create_u8(const char *name, mode_t mode,
+ struct dentry *parent, u8 *value);
+ struct dentry *debugfs_create_u16(const char *name, mode_t mode,
+ struct dentry *parent, u16 *value);
+ struct dentry *debugfs_create_u32(const char *name, mode_t mode,
+ struct dentry *parent, u32 *value);
+ struct dentry *debugfs_create_bool(const char *name, mode_t mode,
+ struct dentry *parent, u32 *value);
+
+Debugfs does not automatically clean up files when a module shuts down, so,
+for every file or directory created with the above functions, there must be a
+call to:
+
+ void debugfs_remove(struct dentry *dentry);
+
+See Documentation/DocBook/filesystems for more details.
_
Patches currently in -mm which might be from shen@xxxxxxxxxxxxxx are
doc-add-documentation-for-debugfs.patch
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