diff options
Diffstat (limited to 'kernel/Documentation/filesystems/sysfs.txt')
| -rw-r--r-- | kernel/Documentation/filesystems/sysfs.txt | 14 |
1 files changed, 9 insertions, 5 deletions
diff --git a/kernel/Documentation/filesystems/sysfs.txt b/kernel/Documentation/filesystems/sysfs.txt index b35a64b82..24da7b32c 100644 --- a/kernel/Documentation/filesystems/sysfs.txt +++ b/kernel/Documentation/filesystems/sysfs.txt @@ -40,7 +40,7 @@ ancestors of object hierarchies; i.e. the subsystems the objects belong to. Sysfs internally stores a pointer to the kobject that implements a -directory in the sysfs_dirent object associated with the directory. In +directory in the kernfs_node object associated with the directory. In the past this kobject pointer has been used by sysfs to do reference counting directly on the kobject whenever the file is opened or closed. With the current sysfs implementation the kobject reference count is @@ -191,9 +191,10 @@ implementations: be called again, rearmed, to fill the buffer. - On write(2), sysfs expects the entire buffer to be passed during the - first write. Sysfs then passes the entire buffer to the store() - method. - + first write. Sysfs then passes the entire buffer to the store() method. + A terminating null is added after the data on stores. This makes + functions like sysfs_streq() safe to use. + When writing sysfs files, userspace processes should first read the entire file, modify the values it wishes to change, then write the entire buffer back. @@ -212,7 +213,10 @@ Other notes: - show() methods should return the number of bytes printed into the buffer. This is the return value of scnprintf(). -- show() should always use scnprintf(). +- show() must not use snprintf() when formatting the value to be + returned to user space. If you can guarantee that an overflow + will never happen you can use sprintf() otherwise you must use + scnprintf(). - store() should return the number of bytes used from the buffer. If the entire buffer has been used, just return the count argument. |