staging: comedi: amplc_pci224: Fix PCI ref count

When attaching a PCI device manually via the comedi driver `attach` hook
(`pci224_attach()`) (called by the comedi core for the
`COMEDI_DEVCONFIG` ioctl), its reference count is incremented in the
`for_each_pci_dev` loop (in `pci224_find_pci_dev()`).  It is decremented
when the `detach` hook (`pci224_detach()`) is called to detach the
device.  However, when the PCI device is attached automatically via the
`attach_pci` hook (`pci224_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 `pci224_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.

Cc: stable <stable@vger.kernel.org> # 3.5.x
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 7 insertions, 0 deletions

diff --git a/drivers/staging/comedi/drivers/amplc_pci224.c b/drivers/staging/comedi/drivers/amplc_pci224.c
index 4e17f13e57f6..8bf109e7bb05 100644
--- a/drivers/staging/comedi/drivers/amplc_pci224.c
+++ b/drivers/staging/comedi/drivers/amplc_pci224.c
@@ -1503,6 +1503,13 @@ pci224_attach_pci(struct comedi_device *dev, struct pci_dev *pci_dev)
                         DRIVER_NAME ": BUG! cannot determine board type!\n");
                 return -EINVAL;
         }
+        /*
+         * Need to 'get' the PCI device to match the 'put' in pci224_detach().
+         * TODO: Remove the pci_dev_get() and matching pci_dev_put() once
+         * support for manual attachment of PCI devices via pci224_attach()
+         * has been removed.
+         */
+        pci_dev_get(pci_dev);
         return pci224_attach_common(dev, pci_dev, NULL);
 }