staging: comedi: amplc_pc236: Fix PCI ref count

When attaching a PCI device manually via the comedi driver `attach` hook
(`pc236_attach()`) (called by the comedi core for the `COMEDI_DEVCONFIG`
ioctl), its reference count is incremented in the `for_each_pci_dev`
loop (in `pc236_find_pci_dev()`).  It is decremented when the `detach`
hook (`pc236_detach()`) is called to detach the device.  However, when
the PCI device is attached automatically via the `attach_pci` hook
(`pc236_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 `pc236_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>

1 files changed, 7 insertions, 0 deletions

diff --git a/drivers/staging/comedi/drivers/amplc_pc236.c b/drivers/staging/comedi/drivers/amplc_pc236.c
index aabba9886b7d..f50287903038 100644
--- a/drivers/staging/comedi/drivers/amplc_pc236.c
+++ b/drivers/staging/comedi/drivers/amplc_pc236.c
@@ -565,6 +565,13 @@ static int __devinit pc236_attach_pci(struct comedi_device *dev,
                 dev_err(dev->class_dev, "BUG! cannot determine board type!\n");
                 return -EINVAL;
         }
+        /*
+         * Need to 'get' the PCI device to match the 'put' in pc236_detach().
+         * TODO: Remove the pci_dev_get() and matching pci_dev_put() once
+         * support for manual attachment of PCI devices via pc236_attach()
+         * has been removed.
+         */
+        pci_dev_get(pci_dev);
         return pc236_pci_common_attach(dev, pci_dev);
 }