file io - Can someone use non-static instance of struct file_operations - Stack Overflow

admin管理员组

文章数量:1302384

I am wondering if it is possible to write a Linux module along the following lines:

fops_impl.h

• Declare the function prototypes of various functions that can be used to initialize members of struct file_operations

fops_impl.c

• Define the various methods that are used to initialize members of struct file_operations

foo_module.c

• #include fops_impl.h
• Define and initialize static instance of struct file_operations
• Use the symbol of struct file_operations to create and register a char device

This code base builds a module i.e. one can load the module as determined by lsmod. However there is no char device and neither are printk statements in the kernel log.

Questions:

• Is it necessary for struct file_operations to be static?
• Is there a working example of a char device where:
• Device registration is one file
• Its file operations is defined in yet another file

I am wondering if it is possible to write a Linux module along the following lines:

fops_impl.h

• Declare the function prototypes of various functions that can be used to initialize members of struct file_operations

fops_impl.c

• Define the various methods that are used to initialize members of struct file_operations

foo_module.c

• #include fops_impl.h
• Define and initialize static instance of struct file_operations
• Use the symbol of struct file_operations to create and register a char device

This code base builds a module i.e. one can load the module as determined by lsmod. However there is no char device and neither are printk statements in the kernel log.

Questions:

• Is it necessary for struct file_operations to be static?
• Is there a working example of a char device where:
• Device registration is one file
• Its file operations is defined in yet another file

• file-io

Share Follow asked Feb 10 at 19:28 saidasasaidasa 1144 bronze badges 1

• Please clarify your specific problem or provide additional details to highlight exactly what you need. As it's currently written, it's hard to tell exactly what you're asking. – Community Bot Commented Feb 13 at 23:53

Add a comment  | 

1 Answer 1

Sorted by: Reset to default 0

I was able to build a "hello world" module with following properties:

file_module.c: Implements the following

• module_init
• Calls method to register char device
• module_exit
• Calls methods to deregister char device

file_chardev.c: Implements the following

• extern struct file_operations
• Method to register a char device
• Method to deregister a char device

file_fops_impl.h: Implements the following

• Declares prototypes of methods used to initialize members of struct file_operations

file_fops.c: Implements the following

• include header file: file_fops_impl.h
• struct file_operation fops = { - - - }

file_fops_impl.c: Implements the following

• include header file: file_fops_impl.h
• Methods that are used to initialize members of struct file_operations

My earlier question became moot when I tried again the same code after a reboot. What is strange is the call to module_init() didn't print any kernel log messages even though I had print statement with error mode.

本文标签： file ioCan someone use nonstatic instance of struct fileoperationsStack Overflow