"Trying to free already-free IRQ 9", but it wasn't freed by me

[nils.stec@googlemail.com (nils.stec)]

Hi,

atm I'm writing a kernel module for an embedded ARM device.
This module uses IRQ9.

If i remove the module, the kernel tells me that:

------------[ cut here ]------------
WARNING: at kernel/irq/manage.c:858 __free_irq+0x84/0x154()
Trying to free already-free IRQ 9
Modules linked in: adc_demo_irq(P-) g_ether pegasus mii
[<c0028794>] (unwind_backtrace+0x0/0xd0) from [<c003b504>] 
(warn_slowpath_common+0x48/0x60)
[<c003b504>] (warn_slowpath_common+0x48/0x60) from [<c003b554>] 
(warn_slowpath_fmt+0x24/0x30)
[<c003b554>] (warn_slowpath_fmt+0x24/0x30) from [<c005fa00>] 
(__free_irq+0x84/0x154)
[<c005fa00>] (__free_irq+0x84/0x154) from [<c005fb0c>] (free_irq+0x3c/0x5c)
[<c005fb0c>] (free_irq+0x3c/0x5c) from [<bf01e18c>] 
(cleanup_module+0x4c/0x60 [adc_demo_irq])
[<bf01e18c>] (cleanup_module+0x4c/0x60 [adc_demo_irq]) from [<c005b898>] 
(sys_delete_module+0x1c4/0x238)
[<c005b898>] (sys_delete_module+0x1c4/0x238) from [<c0022dc0>] 
(ret_fast_syscall+0x0/0x28)
---[ end trace 60d7a16d878ac0b3 ]---
adc testing module removed
------------[ cut here ]------------

The message "adc testing module removed" comes from my module *after* 
free_irq() via printk, so the module exit routine works till the end.

This is my code (only the IRQ related part):

irqreturn_t adc_irq_handler(int irq, void *dev_id) {

     ... do someting ...

     return IRQ_HANDLED;
}

int init_module(void) {
     int32_t retval;
     ...
     retval = request_irq(ADC_IRQ, adc_irq_handler, IRQF_SHARED, 
"lpc313x adc irq", (void *)(adc_irq_handler));
     ...
     return retval;
}

void cleanup_module(void) {
     ...
     free_irq(ADC_IRQ, NULL);        /* remove interrupt handler */
     ...
     return;
}


I hope anyone of you can help me with that problem. If you need more 
information, i'll send it

Greetings,
Nils
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