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: Paul Gortmaker <paul.gortmaker@windriver.com>

diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
index 38518b0880739a5d2dded941e5b6cfbdb85c131d..91d1724e27f36666cc127f58ba333fefaaac7971 100644 (file)
--- a/drivers/scsi/scsi_scan.c
+++ b/drivers/scsi/scsi_scan.c
@@ -295,7 +295,7 @@ 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 ed3b52fba62b201adeb091273a4a6f62ff1476fc..f01117eb43a2decc1fa356d1f6aae51ed0ef0bda 100644 (file)
--- a/drivers/scsi/scsi_sysfs.c
+++ b/drivers/scsi/scsi_sysfs.c
@@ -319,6 +319,7 @@ 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;