staging: comedi: das08: Fix PCI ref count

When attaching a PCI device manually via the comedi driver `attach` hook
(`das08_attach()`) (called by the comedi core for the `COMEDI_DEVCONFIG`
ioctl), its reference count is incremented in the `for_each_pci_dev`
loop (in `das08_find_pci()`).  It is decremented when the `detach` hook
(`das08_detach()`) is called to detach the device.  However, when the
PCI device is attached automatically via the `attach_pci` hook
(`das08_attach_pci()`, called at probe time via
`comedi_pci_auto_config()`) it's reference count is not incremented so
there will be an unmatched decrement when detaching the device.

Increment the PCI device reference count in `das08_attach_pci()` to
correct the mismatch.

Once support for manual configuration has been removed from this driver,
the calls to `pci_dev_get()` and `pci_dev_put()` can be removed.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/comedi/drivers/das08.c

@@ -922,6 +922,13 @@ das08_attach_pci(struct comedi_device *dev, struct pci_dev *pdev)
 		dev_err(dev->class_dev, "BUG! cannot determine board type!\n");
 		return -EINVAL;
 	}
+	/*
+	 * Need to 'get' the PCI device to match the 'put' in das08_detach().
+	 * TODO: Remove the pci_dev_get() and matching pci_dev_put() once
+	 * support for manual attachment of PCI devices via das08_attach()
+	 * has been removed.
+	 */
+	pci_dev_get(pdev);
 	return das08_pci_attach_common(dev, pdev);
 }