IB/hfi1: Do not free hfi1 cdev parent structure early

The deletion of a cdev is not a fence for holding off references to the
structure. The driver attempts to delete the cdev and then proceeds to
free the parent structure, the hfi1_devdata, or dd. This can potentially
lead to a kernel panic in situations where a user has an FD for the cdev
open, and the pci device gets removed. If the user then closes the FD
there will be a NULL dereference when trying to do put on the cdev's
kobject.

Fix this by pointing the cdev's kobject.parent at a new kobject embedded
in its parent structure. Also take a reference when the device is opened
and put it back when it is closed.

Reviewed-by: Mitko Haralanov <mitko.haralanov@intel.com>
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/drivers/staging/rdma/hfi1/device.h b/drivers/staging/rdma/hfi1/device.h
index 5bb3e83cf2da..c3ec19cb0ac9 100644
--- a/drivers/staging/rdma/hfi1/device.h
+++ b/drivers/staging/rdma/hfi1/device.h
@@ -50,7 +50,8 @@
 int hfi1_cdev_init(int minor, const char *name,
 		   const struct file_operations *fops,
 		   struct cdev *cdev, struct device **devp,
-		   bool user_accessible);
+		   bool user_accessible,
+		   struct kobject *parent);
 void hfi1_cdev_cleanup(struct cdev *cdev, struct device **devp);
 const char *class_name(void);
 int __init dev_init(void);