Linux Device Drivers Development

Module unload

The usual command to unload a module is rmmod. You should prefer using this to unload a module loaded with the insmod command. The command should be given the module name to unload as a parameter. Module unloading is a kernel feature that you can enable or disable, according to the value of the CONFIG_MODULE_UNLOAD config option. Without this option, you will not be able to unload any modules. Let's enable module unloading support:

CONFIG_MODULE_UNLOAD=y 

At runtime, the kernel will prevent you from unloading modules that may break things, even if you ask it to do so. This is because the kernel keeps a reference count on module usage, so that it knows whether a module is actually in use or not. If the kernel believes it is unsafe ...