i5000-edac: hold reference to mci kobject

It turns out that edac_mc_del_mc will kobject_put the last kref on the
mci object.

If the timing is just right, that means that the mci object is freed
before before i5000_remove_one has a chance to free the resources
associated with it, causing a null pointer exceptions when unloading the
driver.  Insert a kobject_{get,put} pair so that this doesn't happen.
Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Cc: Doug Thompson <norsk5@yahoo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/edac/i5000_edac.c

@@ -1381,6 +1381,7 @@ static int i5000_probe1(struct pci_dev *pdev, int dev_idx)
 	if (mci == NULL)
 		return -ENOMEM;
 
+	kobject_get(&mci->edac_mci_kobj);
 	debugf0("MC: " __FILE__ ": %s(): mci = %p\n", __func__, mci);
 
 	mci->dev = &pdev->dev;	/* record ptr  to the generic device */
@@ -1453,6 +1454,7 @@ static int i5000_probe1(struct pci_dev *pdev, int dev_idx)
 	i5000_put_devices(mci);
 
 fail0:
+	kobject_put(&mci->edac_mci_kobj);
 	edac_mc_free(mci);
 	return -ENODEV;
 }
@@ -1498,7 +1500,7 @@ static void __devexit i5000_remove_one(struct pci_dev *pdev)
 
 	/* retrieve references to resources, and free those resources */
 	i5000_put_devices(mci);
-
+	kobject_put(&mci->edac_mci_kobj);
 	edac_mc_free(mci);
 }