Remove unsafe try_module_get(THIS_MODULE) #328
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linD026
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Aug 5, 2025
lkmpg.tex
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| It is important to keep the counter accurate; if you ever lose track of the correct usage count, you will never be able to unload the module; it is now reboot time. | ||
| This is bound to happen to you sooner or later during a module's development. | ||
| Note: The use of \cpp|try_module_get(THIS_MODULE)| and \cpp|module_put(THIS_MODULE)| within a module's own code is considered unsafe and should be avoided. | ||
| The kernel automatically manages the reference count when file operations are in progress, so manual reference counting is unnecessary and can lead to race conditions. |
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It would be better to have some external references to this, such as:
This commit removes all instances of try_module_get(THIS_MODULE) and corresponding module_put(THIS_MODULE) calls from example modules. This pattern is considered unsafe because: - The kernel automatically manages module reference counting during file operations - Manual reference counting within a module's own code can lead to race conditions - It is redundant and unnecessary for proper module operation It also updates documentation to: - Remove references to try_module_get/module_put functions - Add note explaining why these functions should be avoided - Keep only module_refcount() as a safe display function Close #52
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This commit removes all instances of try_module_get(THIS_MODULE) and corresponding module_put(THIS_MODULE) calls from example modules. This pattern is considered unsafe because:
It also updates documentation to:
Close #52
Summary by Bito
This pull request enhances kernel module safety by removing unsafe functions try_module_get(THIS_MODULE) and module_put(THIS_MODULE), which can cause race conditions. It promotes the use of the safe module_refcount() function and updates the documentation accordingly.