[SCSI] osduld: Ref-counting bug fix

If scsi has released the device (logout), and exofs has last
reference on the osduld_device it will be freed by
osd_uld_release() within the call to fput(). But this will
oops in cdev_release() which is called after the fops->release.
(cdev is embedded within osduld_device). __uld_get/put pair
makes sure we have a cdev for the duration of fput()

Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>

1 files changed, 8 insertions, 0 deletions

diff --git a/drivers/scsi/osd/osd_uld.c b/drivers/scsi/osd/osd_uld.c
index 0bdef3390902..1ea6447f9418 100644
--- a/drivers/scsi/osd/osd_uld.c
+++ b/drivers/scsi/osd/osd_uld.c
@@ -224,7 +224,15 @@ void osduld_put_device(struct osd_dev *od)
 
                 BUG_ON(od->scsi_device != oud->od.scsi_device);
 
+                /* If scsi has released the device (logout), and exofs has last
+                 * reference on oud it will be freed by above osd_uld_release
+                 * within fput below. But this will oops in cdev_release which
+                 * is called after the fops->release. __uld_get/put pair makes
+                 * sure we have a cdev for the duration of fput
+                 */
+                __uld_get(oud);
                 fput(od->file);
+                __uld_put(oud);
                 kfree(od);
         }
 }