On Sat, 21 Jul 2001 23:02:53 +0100, Steve Papacharalambous <stevep@lineo.com> wrote: >Are there any limitations or precautions needed with interrupt handlers >in loadable modules? There is a potential race condition when removing the module. rmmod will remove a module when its use count is zero. If the interrupt handler is invoked after the use count is tested but before the module cleanup routine is entered then the code can be removed while the interrupt handler is running. The 2.5 module load/unload system will remove this race. In 2.4, your best option is to set a can_unload() function in the module. Unregister the interrupt handler in can_unload(), wait until the interrupt count goes to zero (might be running on another cpu) then return 0. See drivers/char/ftape/compressor/zftape-compress.c for an example. Alternatively keep a use count for opens on the device. This assumes that the device does not generate interrupts while it is not open, not always true.
