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Subject[PATCH 1/2] debugfs: update documented return values of debugfs helpers
Date
Since commit ff9fb72bc077 ("debugfs: return error values, not NULL")
these helper functions do not return NULL anymore (with the exception
of debugfs_create_u32_array()).

Signed-off-by: Ronald Tschalär <ronald@innovation.ch>
---
Documentation/filesystems/debugfs.txt | 16 +++---
fs/debugfs/file.c | 77 ++++++++++++---------------
2 files changed, 44 insertions(+), 49 deletions(-)

diff --git a/Documentation/filesystems/debugfs.txt b/Documentation/filesystems/debugfs.txt
index 4f45f71149cb..4a0a9c3f4af6 100644
--- a/Documentation/filesystems/debugfs.txt
+++ b/Documentation/filesystems/debugfs.txt
@@ -31,10 +31,10 @@ This call, if successful, will make a directory called name underneath the
indicated parent directory. If parent is NULL, the directory will be
created in the debugfs root. On success, the return value is a struct
dentry pointer which can be used to create files in the directory (and to
-clean it up at the end). A NULL return value indicates that something went
-wrong. If ERR_PTR(-ENODEV) is returned, that is an indication that the
-kernel has been built without debugfs support and none of the functions
-described below will work.
+clean it up at the end). An ERR_PTR(-ERROR) return value indicates that
+something went wrong. If ERR_PTR(-ENODEV) is returned, that is an
+indication that the kernel has been built without debugfs support and none
+of the functions described below will work.

The most general way to create a file within a debugfs directory is with:

@@ -48,8 +48,9 @@ should hold the file, data will be stored in the i_private field of the
resulting inode structure, and fops is a set of file operations which
implement the file's behavior. At a minimum, the read() and/or write()
operations should be provided; others can be included as needed. Again,
-the return value will be a dentry pointer to the created file, NULL for
-error, or ERR_PTR(-ENODEV) if debugfs support is missing.
+the return value will be a dentry pointer to the created file,
+ERR_PTR(-ERROR) on error, or ERR_PTR(-ENODEV) if debugfs support is
+missing.

Create a file with an initial size, the following function can be used
instead:
@@ -214,7 +215,8 @@ can be removed with:

void debugfs_remove(struct dentry *dentry);

-The dentry value can be NULL, in which case nothing will be removed.
+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
diff --git a/fs/debugfs/file.c b/fs/debugfs/file.c
index 4fce1da7db23..ddd708b09fa1 100644
--- a/fs/debugfs/file.c
+++ b/fs/debugfs/file.c
@@ -394,12 +394,11 @@ DEFINE_DEBUGFS_ATTRIBUTE(fops_u8_wo, NULL, debugfs_u8_set, "%llu\n");
* 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.
+ * you are responsible here.) If an error occurs, %ERR_PTR(-ERROR) 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.
+ * If debugfs is not enabled in the kernel, the value %ERR_PTR(-ENODEV) will
+ * be returned.
*/
struct dentry *debugfs_create_u8(const char *name, umode_t mode,
struct dentry *parent, u8 *value)
@@ -440,12 +439,11 @@ DEFINE_DEBUGFS_ATTRIBUTE(fops_u16_wo, NULL, debugfs_u16_set, "%llu\n");
* 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.
+ * you are responsible here.) If an error occurs, %ERR_PTR(-ERROR) 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.
+ * If debugfs is not enabled in the kernel, the value %ERR_PTR(-ENODEV) will
+ * be returned.
*/
struct dentry *debugfs_create_u16(const char *name, umode_t mode,
struct dentry *parent, u16 *value)
@@ -486,12 +484,11 @@ DEFINE_DEBUGFS_ATTRIBUTE(fops_u32_wo, NULL, debugfs_u32_set, "%llu\n");
* 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.
+ * you are responsible here.) If an error occurs, %ERR_PTR(-ERROR) 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.
+ * If debugfs is not enabled in the kernel, the value %ERR_PTR(-ENODEV) will
+ * be returned.
*/
struct dentry *debugfs_create_u32(const char *name, umode_t mode,
struct dentry *parent, u32 *value)
@@ -533,12 +530,11 @@ DEFINE_DEBUGFS_ATTRIBUTE(fops_u64_wo, NULL, debugfs_u64_set, "%llu\n");
* 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.
+ * you are responsible here.) If an error occurs, %ERR_PTR(-ERROR) 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.
+ * If debugfs is not enabled in the kernel, the value %ERR_PTR(-ENODEV) will
+ * be returned.
*/
struct dentry *debugfs_create_u64(const char *name, umode_t mode,
struct dentry *parent, u64 *value)
@@ -582,12 +578,11 @@ DEFINE_DEBUGFS_ATTRIBUTE(fops_ulong_wo, NULL, debugfs_ulong_set, "%llu\n");
* 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.
+ * you are responsible here.) If an error occurs, %ERR_PTR(-ERROR) 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.
+ * If debugfs is not enabled in the kernel, the value %ERR_PTR(-ENODEV) will
+ * be returned.
*/
struct dentry *debugfs_create_ulong(const char *name, umode_t mode,
struct dentry *parent, unsigned long *value)
@@ -850,12 +845,11 @@ static const struct file_operations fops_bool_wo = {
* 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.
+ * you are responsible here.) If an error occurs, %ERR_PTR(-ERROR) 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.
+ * If debugfs is not enabled in the kernel, the value %ERR_PTR(-ENODEV) will
+ * be returned.
*/
struct dentry *debugfs_create_bool(const char *name, umode_t mode,
struct dentry *parent, bool *value)
@@ -904,12 +898,11 @@ static const struct file_operations fops_blob = {
* 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.
+ * you are responsible here.) If an error occurs, %ERR_PTR(-ERROR) 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.
+ * If debugfs is not enabled in the kernel, the value %ERR_PTR(-ENODEV) will
+ * be returned.
*/
struct dentry *debugfs_create_blob(const char *name, umode_t mode,
struct dentry *parent,
@@ -1005,8 +998,9 @@ static const struct file_operations u32_array_fops = {
* Writing is not supported. Seek within the file is also not supported.
* Once array is created its size can not be changed.
*
- * The function returns a pointer to dentry on success. If debugfs is not
- * enabled in the kernel, the value -%ENODEV will be returned.
+ * The function returns a pointer to dentry on success. If an error occurs,
+ * %ERR_PTR(-ERROR) or NULL will be returned. If debugfs is not enabled in
+ * the kernel, the value %ERR_PTR(-ENODEV) will be returned.
*/
struct dentry *debugfs_create_u32_array(const char *name, umode_t mode,
struct dentry *parent,
@@ -1102,12 +1096,11 @@ static const struct file_operations fops_regset32 = {
* 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.
+ * you are responsible here.) If an error occurs, %ERR_PTR(-ERROR) 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.
+ * If debugfs is not enabled in the kernel, the value %ERR_PTR(-ENODEV) will
+ * be returned.
*/
struct dentry *debugfs_create_regset32(const char *name, umode_t mode,
struct dentry *parent,
--
2.20.1
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