updates for CFQ oops fix

- add a comment to the device structure that the device_busy field
  is now protected by the request_queue->queue_lock
- null out sdev->request_queue after the queue is released to trap
  any (and there shouldn't be any) use after the queue is freed.

Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

2 files changed, 4 insertions, 0 deletions

diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
index 134d3a3e4222..e75ee4671ee3 100644
--- a/drivers/scsi/scsi_sysfs.c
+++ b/drivers/scsi/scsi_sysfs.c
@@ -171,6 +171,9 @@ void scsi_device_dev_release(struct device *dev)
         if (sdev->request_queue) {
                 sdev->request_queue->queuedata = NULL;
                 scsi_free_queue(sdev->request_queue);
+                /* temporary expedient, try to catch use of queue lock
+                 * after free of sdev */
+                sdev->request_queue = NULL;
         }
 
         scsi_target_reap(scsi_target(sdev));
diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h
index f6d051318299..fe9571d2e306 100644
--- a/include/scsi/scsi_device.h
+++ b/include/scsi/scsi_device.h
@@ -43,6 +43,7 @@ struct scsi_device {
         struct list_head    siblings;   /* list of all devices on this host */
         struct list_head    same_target_siblings; /* just the devices sharing same target id */
 
+        /* this is now protected by the request_queue->queue_lock */
         volatile unsigned short device_busy;    /* commands actually active on low-level */
         spinlock_t list_lock;
         struct list_head cmd_list;      /* queue of in use SCSI Command structures */