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
......@@ -251,3 +251,49 @@ struct dentry *debugfs_create_bool(const char *name, mode_t mode,
}
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);
......@@ -21,6 +21,11 @@
struct file_operations;
struct debugfs_blob_wrapper {
void *data;
unsigned long size;
};
#if defined(CONFIG_DEBUG_FS)
struct dentry *debugfs_create_file(const char *name, mode_t mode,
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 *parent, u32 *value);
struct dentry *debugfs_create_blob(const char *name, mode_t mode,
struct dentry *parent,
struct debugfs_blob_wrapper *blob);
#else
#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);
}
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
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