[PATCH] p00001_scsi_tcq_queue_lock

[Brian King <brking@us.ibm.com>]

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-- 
Brian King
eServer Storage I/O
IBM Linux Technology Center

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Add locking to scsi_activate_tcq and scsi_deactivate_tcq to fix a race
condition that can occur when disabling tcqing with commands in flight.

Signed-off-by: Brian King <brking@us.ibm.com>
---

 linux-2.6.8-rc2-bjking1/include/scsi/scsi_tcq.h |    8 ++++++++
 1 files changed, 8 insertions(+)

diff -puN include/scsi/scsi_tcq.h~scsi_tcq_queue_lock include/scsi/scsi_tcq.h
--- linux-2.6.8-rc2/include/scsi/scsi_tcq.h~scsi_tcq_queue_lock	2004-08-03 11:05:28.000000000 -0500
+++ linux-2.6.8-rc2-bjking1/include/scsi/scsi_tcq.h	2004-08-03 11:12:19.000000000 -0500
@@ -25,9 +25,13 @@
  **/
 static inline void scsi_activate_tcq(struct scsi_device *sdev, int depth)
 {
+	unsigned long flags;
+
         if (sdev->tagged_supported) {
+		spin_lock_irqsave(sdev->request_queue->queue_lock, flags);
 		if (!blk_queue_tagged(sdev->request_queue))
 			blk_queue_init_tags(sdev->request_queue, depth, NULL);
+		spin_unlock_irqrestore(sdev->request_queue->queue_lock, flags);
 		scsi_adjust_queue_depth(sdev, MSG_ORDERED_TAG, depth);
         }
 }
@@ -38,8 +42,12 @@ static inline void scsi_activate_tcq(str
  **/
 static inline void scsi_deactivate_tcq(struct scsi_device *sdev, int depth)
 {
+	unsigned long flags;
+
+	spin_lock_irqsave(sdev->request_queue->queue_lock, flags);
 	if (blk_queue_tagged(sdev->request_queue))
 		blk_queue_free_tags(sdev->request_queue);
+	spin_unlock_irqrestore(sdev->request_queue->queue_lock, flags);
 	scsi_adjust_queue_depth(sdev, 0, depth);
 }
 
_