[SCSI] hpsa: do not give up retry of driver cmds after only 3 retries

Instead of giving up after 3 immediate retries of driver initiated
commands, back off the rate of retries and retry a bunch more times.
Signed-off-by: NStephen M. Cameron <scameron@beardog.cce.hp.com>
Reviewed-by: Andi Shyti <andi.shyti@gmail.com> 
Signed-off-by: NJames Bottomley <JBottomley@Parallels.com>

drivers/scsi/hpsa.c

@@ -1380,17 +1380,24 @@ static void hpsa_scsi_do_simple_cmd_core_if_no_lockup(struct ctlr_info *h,
 	}
 }
 
+#define MAX_DRIVER_CMD_RETRIES 25
 static void hpsa_scsi_do_simple_cmd_with_retry(struct ctlr_info *h,
 	struct CommandList *c, int data_direction)
 {
-	int retry_count = 0;
+	int backoff_time = 10, retry_count = 0;
 
 	do {
 		memset(c->err_info, 0, sizeof(*c->err_info));
 		hpsa_scsi_do_simple_cmd_core(h, c);
 		retry_count++;
+		if (retry_count > 3) {
+			msleep(backoff_time);
+			if (backoff_time < 1000)
+				backoff_time *= 2;
+		}
 	} while ((check_for_unit_attention(h, c) ||
-			check_for_busy(h, c)) && retry_count <= 3);
+			check_for_busy(h, c)) &&
+			retry_count <= MAX_DRIVER_CMD_RETRIES);
 	hpsa_pci_unmap(h->pdev, c, 1, data_direction);
 }