[SCSI] aic94xx SCSI timeout fix: SMP retry fix.

Updating DDB0 inside aic94xx driver itself caused SMP command timeout. I
hit this SMP timeout problem twice but I am not able to reproduce it since
then. Here is a fix that retries an SMP command.
Signed-off-by: Malahal Naineni <malahal@us.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

drivers/scsi/libsas/sas_expander.c

@@ -71,11 +71,13 @@ static void smp_task_done(struct sas_task *task)
 static int smp_execute_task(struct domain_device *dev, void *req, int req_size,
 			    void *resp, int resp_size)
 {
-	int res;
-	struct sas_task *task = sas_alloc_task(GFP_KERNEL);
+	int res, retry;
+	struct sas_task *task = NULL;
 	struct sas_internal *i =
 		to_sas_internal(dev->port->ha->core.shost->transportt);
 
+	for (retry = 0; retry < 3; retry++) {
+		task = sas_alloc_task(GFP_KERNEL);
 		if (!task)
 			return -ENOMEM;
 
@@ -110,16 +112,24 @@ static int smp_execute_task(struct domain_device *dev, void *req, int req_size,
 			}
 		}
 		if (task->task_status.resp == SAS_TASK_COMPLETE &&
-	    task->task_status.stat == SAM_GOOD)
+		    task->task_status.stat == SAM_GOOD) {
 			res = 0;
-	else
+			break;
+		} else {
 			SAS_DPRINTK("%s: task to dev %016llx response: 0x%x "
 				    "status 0x%x\n", __FUNCTION__,
 				    SAS_ADDR(dev->sas_addr),
 				    task->task_status.resp,
 				    task->task_status.stat);
+			sas_free_task(task);
+			task = NULL;
+		}
+	}
 ex_err:
+	BUG_ON(retry == 3 && task != NULL);
+	if (task != NULL) {
 		sas_free_task(task);
+	}
 	return res;
 }