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Diffstat (limited to 'Documentation/filesystems/debugfs.rst')
| -rw-r--r-- | Documentation/filesystems/debugfs.rst | 57 |
1 files changed, 26 insertions, 31 deletions
diff --git a/Documentation/filesystems/debugfs.rst b/Documentation/filesystems/debugfs.rst index 1da7a4b7383d..55f807293924 100644 --- a/Documentation/filesystems/debugfs.rst +++ b/Documentation/filesystems/debugfs.rst @@ -120,8 +120,8 @@ and hexadecimal:: Boolean values can be placed in debugfs with:: - struct dentry *debugfs_create_bool(const char *name, umode_t mode, - struct dentry *parent, bool *value); + void debugfs_create_bool(const char *name, umode_t mode, + struct dentry *parent, bool *value); A read on the resulting file will yield either Y (for non-zero values) or N, followed by a newline. If written to, it will accept either upper- or @@ -155,8 +155,8 @@ any code which does so in the mainline. Note that all files created with debugfs_create_blob() are read-only. If you want to dump a block of registers (something that happens quite -often during development, even if little such code reaches mainline. -Debugfs offers two functions: one to make a registers-only file, and +often during development, even if little such code reaches mainline), +debugfs offers two functions: one to make a registers-only file, and another to insert a register block in the middle of another sequential file:: @@ -183,19 +183,23 @@ The "base" argument may be 0, but you may want to build the reg32 array using __stringify, and a number of register names (macros) are actually byte offsets over a base for the register block. -If you want to dump an u32 array in debugfs, you can create file with:: +If you want to dump a u32 array in debugfs, you can create a file with:: + + struct debugfs_u32_array { + u32 *array; + u32 n_elements; + }; void debugfs_create_u32_array(const char *name, umode_t mode, struct dentry *parent, - u32 *array, u32 elements); + struct debugfs_u32_array *array); -The "array" argument provides data, and the "elements" argument is -the number of elements in the array. Note: Once array is created its -size can not be changed. +The "array" argument wraps a pointer to the array's data and the number +of its elements. Note: Once array is created its size can not be changed. -There is a helper function to create device related seq_file:: +There is a helper function to create a device-related seq_file:: - struct dentry *debugfs_create_devm_seqfile(struct device *dev, + void debugfs_create_devm_seqfile(struct device *dev, const char *name, struct dentry *parent, int (*read_fn)(struct seq_file *s, @@ -207,18 +211,16 @@ seq_file content. There are a couple of other directory-oriented helper functions:: - struct dentry *debugfs_rename(struct dentry *old_dir, - struct dentry *old_dentry, - struct dentry *new_dir, - const char *new_name); + struct dentry *debugfs_change_name(struct dentry *dentry, + const char *fmt, ...); struct dentry *debugfs_create_symlink(const char *name, struct dentry *parent, const char *target); -A call to debugfs_rename() will give a new name to an existing debugfs -file, possibly in a different directory. The new_name must not exist prior -to the call; the return value is old_dentry with updated information. +A call to debugfs_change_name() will give a new name to an existing debugfs +file, always in the same directory. The new_name must not exist prior +to the call; the return value is 0 on success and -E... on failure. Symbolic links can be created with debugfs_create_symlink(). There is one important thing that all debugfs users must take into account: @@ -227,22 +229,15 @@ module is unloaded without explicitly removing debugfs entries, the result will be a lot of stale pointers and no end of highly antisocial behavior. So all debugfs users - at least those which can be built as modules - must be prepared to remove all files and directories they create there. A file -can be removed with:: +or directory can be removed with:: void debugfs_remove(struct dentry *dentry); The dentry value can be NULL or an error value, in which case nothing will -be removed. - -Once upon a time, debugfs users were required to remember the dentry -pointer for every debugfs file they created so that all files could be -cleaned up. We live in more civilized times now, though, and debugfs users -can call:: - - void debugfs_remove_recursive(struct dentry *dentry); - -If this function is passed a pointer for the dentry corresponding to the -top-level directory, the entire hierarchy below that directory will be -removed. +be removed. Note that this function will recursively remove all files and +directories underneath it. Previously, debugfs_remove_recursive() was used +to perform that task, but this function is now just an alias to +debugfs_remove(). debugfs_remove_recursive() should be considered +deprecated. .. [1] http://lwn.net/Articles/309298/ |