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OSKextReleaseKextWithLoadTag

Release a loaded kext based on its load tag.

Declaration

OSReturn OSKextReleaseKextWithLoadTag(OSKextLoadTag loadTag);

Parameters

Return Value

kOSReturnSuccess if the kext was released. kOSKextReturnNotFound if the kext was not found. kOSKextReturnInvalidArgument if loadTag is kOSKextInvalidLoadTag.

Discussion

The kext should have been retained previously via OSKextRetainKextWithLoadTag.

This function schedules an autounload scan for all kexts. When that scan occurs, if a kext has autounload enabled, it will be unloaded if there are no outstanding references to it and there are no instances of its Libkern C++ classes (if any).

Kexts that define subclasses of IOService have autounload enabled automatically. Other kexts can use the reference count to manage automatic unload without having to define and create Libkern C++ objects. For example, a filesystem kext can be retained whenever a new mount is created, and released when a mount is removed. When the last mount is removed, the kext will be unloaded after a brief delay.

While the autounload scan takes place after a delay of at least a minute, a kext that manages its own reference counts for autounload should be prepared to have its module stop function called even while the function calling this function is still running.

A kext can get its own load tag using the OSKextGetCurrentLoadTag.

Kexts should not retain and release other kexts; linkage references are accounted for internally.

See Also

kext