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Commit dd308bc3 authored by Michael Ellerman's avatar Michael Ellerman Committed by Greg Kroah-Hartman
Browse files

[PATCH] debugfs: Add debugfs_create_blob() helper for exporting binary data 



I wanted to export a binary blob via debugfs, and although it was pretty easy
it seems like it'd be easier if there was a helper for it. It's a pity we need
the wrapper struct but I can't see a cleaner way to do it.

Signed-off-by: default avatarMichael Ellerman <michael@ellerman.id.au>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent c516865c

fs/debugfs/file.c

+46 −0
Original line number Original line Diff line number Diff line
@@ -251,3 +251,49 @@ struct dentry *debugfs_create_bool(const char *name, mode_t mode, 
}

}

EXPORT_SYMBOL_GPL(debugfs_create_bool);

EXPORT_SYMBOL_GPL(debugfs_create_bool);





static ssize_t read_file_blob(struct file *file, char __user *user_buf,

			      size_t count, loff_t *ppos)

{

	struct debugfs_blob_wrapper *blob = file->private_data;

	return simple_read_from_buffer(user_buf, count, ppos, blob->data,

			blob->size);

}



static struct file_operations fops_blob = {

	.read =		read_file_blob,

	.open =		default_open,

};



/**

 * debugfs_create_blob - create a file in the debugfs filesystem that is

 * used to read and write a binary blob.

 *

 * @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 paramater is NULL, then the

 *          file will be created in the root of the debugfs filesystem.

 * @blob: a pointer to a struct debugfs_blob_wrapper which contains a pointer

 *        to the blob data and the size of the data.

 *

 * This function creates a file in debugfs with the given name that exports

 * @blob->data as a binary blob. If the @mode variable is so set it can be

 * read from. Writing is not supported.

 *

 * This function will return a pointer to a dentry if it succeeds.  This

 * pointer must be passed to the debugfs_remove() function when the file is

 * to be removed (no automatic cleanup happens if your module is unloaded,

 * you are responsible here.)  If an error occurs, NULL will be returned.

 *

 * If debugfs is not enabled in the kernel, the value -ENODEV will be

 * returned.  It is not wise to check for this value, but rather, check for

 * NULL or !NULL instead as to eliminate the need for #ifdef in the calling

 * code.

 */

struct dentry *debugfs_create_blob(const char *name, mode_t mode,

				   struct dentry *parent,

				   struct debugfs_blob_wrapper *blob)

{

	return debugfs_create_file(name, mode, parent, blob, &fops_blob);

}

EXPORT_SYMBOL_GPL(debugfs_create_blob);

include/linux/debugfs.h

+15 −0
Original line number Original line Diff line number Diff line
@@ -21,6 +21,11 @@ 




struct file_operations;

struct file_operations;





struct debugfs_blob_wrapper {

	void *data;

	unsigned long size;

};



#if defined(CONFIG_DEBUG_FS)

#if defined(CONFIG_DEBUG_FS)

struct dentry *debugfs_create_file(const char *name, mode_t mode,

struct dentry *debugfs_create_file(const char *name, mode_t mode,

				   struct dentry *parent, void *data,

				   struct dentry *parent, void *data,
@@ -39,6 +44,9 @@ struct dentry *debugfs_create_u32(const char *name, mode_t mode, 
struct dentry *debugfs_create_bool(const char *name, mode_t mode,

struct dentry *debugfs_create_bool(const char *name, mode_t mode,

				  struct dentry *parent, u32 *value);

				  struct dentry *parent, u32 *value);





struct dentry *debugfs_create_blob(const char *name, mode_t mode,

				  struct dentry *parent,

				  struct debugfs_blob_wrapper *blob);

#else

#else





#include <linux/err.h>

#include <linux/err.h>
@@ -94,6 +102,13 @@ static inline struct dentry *debugfs_create_bool(const char *name, mode_t mode, 
	return ERR_PTR(-ENODEV);

	return ERR_PTR(-ENODEV);

}

}





static inline struct dentry *debugfs_create_blob(const char *name, mode_t mode,

				  struct dentry *parent,

				  struct debugfs_blob_wrapper *blob)

{

	return ERR_PTR(-ENODEV);

}



#endif

#endif





#endif
 
#endif