[SCSI] hpsa: do not attempt to flush the cache on locked up controllers

There's no point in trying since it can't work, and if you do
try, it will just hang the system on shutdown.
Signed-off-by: Stephen M. Cameron <scameron@beardog.cce.hp.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

drivers/scsi/hpsa.c

@@ -4942,6 +4942,15 @@ static void hpsa_flush_cache(struct ctlr_info *h)
 {
 	char *flush_buf;
 	struct CommandList *c;
+	unsigned long flags;
+
+	/* Don't bother trying to flush the cache if locked up */
+	spin_lock_irqsave(&h->lock, flags);
+	if (unlikely(h->lockup_detected)) {
+		spin_unlock_irqrestore(&h->lock, flags);
+		return;
+	}
+	spin_unlock_irqrestore(&h->lock, flags);
 
 	flush_buf = kzalloc(4, GFP_KERNEL);
 	if (!flush_buf)