Fix oops caused by queue refcounting failure

commit e73e079bf128d68284efedeba1fbbc18d78610f9 upstream.

In certain circumstances, we can get an oops from a torn down device.
Most notably this is from CD roms trying to call scsi_ioctl.  The root
cause of the problem is the fact that after scsi_remove_device() has
been called, the queue is fully torn down.  This is actually wrong
since the queue can be used until the sdev release function is called.
Therefore, we add an extra reference to the queue which is released in
sdev->release, so the queue always exists.

Reported-by: Parag Warudkar <parag.lkml@gmail.com>
Signed-off-by: James Bottomley <jbottomley@parallels.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
index ed1dfa9174520b342144412128a77e2e88497008..04830e8fc62c24c2522262690e455146c13efc7d 100644 (file)
--- a/drivers/scsi/scsi_scan.c
+++ b/drivers/scsi/scsi_scan.c
@@ -293,7 +293,7 @@ static struct scsi_device *scsi_alloc_sdev(struct scsi_target *starget,
                kfree(sdev);
                goto out;
        }
-
+       blk_get_queue(sdev->request_queue);
        sdev->request_queue->queuedata = sdev;
        scsi_adjust_queue_depth(sdev, 0, sdev->host->cmd_per_lun);
 

diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
index 66d33c38af774e2d801715637fe8f69eaaa0bad8..91a93e0ed67a4f3a7853b9a2956419b9fd99c2a3 100644 (file)
--- a/drivers/scsi/scsi_sysfs.c
+++ b/drivers/scsi/scsi_sysfs.c
@@ -318,6 +318,7 @@ static void scsi_device_dev_release_usercontext(struct work_struct *work)
                kfree(evt);
        }
 
+       blk_put_queue(sdev->request_queue);
        /* NULL queue means the device can't be used */
        sdev->request_queue = NULL;