Re: free free irq and Oops on cat /proc/interrupts (2)

[Sergey Vlasov <vsu@altlinux.ru>]

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On Sat, Sep 17, 2005 at 10:25:23PM +0400, Manu Abraham wrote:
[skip]
> static int __devinit mantis_pci_probe(struct pci_dev *pdev,
> 				const struct pci_device_id *mantis_pci_table)
> {
> 	u8 revision, latency;
> 	struct mantis_pci *mantis;
> 
> 	mantis = (struct mantis_pci *)
> 				kmalloc(sizeof (struct mantis_pci), GFP_KERNEL);
> 	if (mantis == NULL) {
> 		dprintk(verbose, MANTIS_ERROR, 1, "Out of memory");
> 		return -ENOMEM;
> 	}
> 	if (pci_enable_device(pdev)) {
> 		dprintk(verbose, MANTIS_ERROR, 1, "Mantis PCI enable failed");
> 		goto err;
> 	}
> 	dprintk(verbose, MANTIS_ERROR, 1, "<2:>IRQ=%d", pdev->irq);
> 
> 	dprintk(verbose, MANTIS_ERROR, 1, "Got a device");
> 	if (request_irq(pdev->irq, mantis_pci_irq, SA_SHIRQ | SA_INTERRUPT, 
> 						DRIVER_NAME, mantis) < 0) {

Some code is obviously missing here...

> 	dprintk(verbose, MANTIS_DEBUG, 1, "We got an IRQ");
> 	return 0;
> 
> err:
> 	dprintk(verbose, MANTIS_DEBUG, 1, "<freak out>");
> 	kfree(mantis);
> 	return -ENODEV;
> }
> 
> 
> 
> static void __devexit mantis_pci_remove(struct pci_dev *pdev)
> {
> 	free_irq(pdev->irq, pdev);

Here is the next problem - you must give free_irq() the same pointer
that you have passed to request_irq().  So you need a way to get from
a struct pci_dev for your device to the corresponding struct
mantis_pci.  This is done as follows:

1) In your mantis_pci_probe(), when you have initialized the device
successfully, put the pointer to you data structure into the PCI
device structure:

	pci_set_drvdata(pdev, mantis);

2) In mantis_pci_remove() (and later in other PCI driver functions,
like suspend/resume) get this pointer back:

	struct mantis_pci *mantis = pci_get_drvdata(pdev);

Then use that pointer where you need it (e.g., in free_irq()).

3) mantis_pci_remove() should also clear out the pointer to the driver
data:

	pci_set_drvdata(pdev, NULL);

> 	pci_disable_device(pdev);
> }

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