Fix incorrect conditional usage of .owner #349
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EricccTaiwan
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Sep 18, 2025
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Hmm. So it looks like the new kernel even removed the .owner field from struct class? I’ll double-check. |
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jserv
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Sep 19, 2025
The examples code wrapped .owner = THIS_MODULE inside version checks,
suggesting that it is no longer needed after v6.4. This is only true
for driver types where the driver core sets .owner automatically (e.g.
platform and i2c drivers).
For structures such as struct file_operations, .owner must still be set
explicitly by the user. Without it, module reference counting will be
broken, allowing a module to be unloaded while still in use, which can
lead to kernel panics.
struct class is a special case: its .owner field was removed in
upstream Linux commit 6e30a66433af ("driver core: class: remove struct
module owner out of struct class"). Explicitly setting .owner for
struct class is safe on older kernels but must be conditionally
compiled out on newer kernels.
Remove the unnecessary version guards and unconditionally sets
.owner = THIS_MODULE in the affected example code.
Closes: sysprog21#348
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The examples code wrapped .owner = THIS_MODULE inside version checks, suggesting that it is no longer needed after v6.4. This is only true for driver types where the driver core sets .owner automatically (e.g. platform and i2c drivers).
For structures such as struct file_operations, .owner must still be set explicitly by the user. Without it, module reference counting will be broken, allowing a module to be unloaded while still in use, which can lead to kernel panics.
struct class is a special case: its .owner field was removed in upstream Linux commit 6e30a66433af ("driver core: class: remove struct module owner out of struct class"). Explicitly setting .owner for struct class is safe on older kernels but must be conditionally compiled out on newer kernels.
Remove the unnecessary version guards and unconditionally sets .owner = THIS_MODULE in the affected example code.
Closes: #348
Summary by cubic
Remove version guards and always set .owner = THIS_MODULE in example drivers to fix module refcounting and avoid unload panics. This also makes the examples clearer.