qlcnic: Flush mailbox command list when mailbox is not available

o Driver was hitting a panic at the time of adapter reset due to invalid command
  access from the list which had been already freed by the queuing thread.
  Flush all the pending commands from the list before proceeding with adapter reset
Signed-off-by: Manish Chopra <manish.chopra@qlogic.com>
Signed-off-by: Sucheta Chakraborty <sucheta.chakraborty@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/qlogic/qlcnic/qlcnic_83xx_hw.c

@@ -3515,6 +3515,8 @@ static inline void qlcnic_83xx_flush_mbx_queue(struct qlcnic_adapter *adapter)
 
 	while (!list_empty(head)) {
 		cmd = list_entry(head->next, struct qlcnic_cmd_args, list);
+		dev_info(&adapter->pdev->dev, "%s: Mailbox command 0x%x\n",
+			 __func__, cmd->cmd_op);
 		list_del(&cmd->list);
 		mbx->num_cmds--;
 		qlcnic_83xx_notify_cmd_completion(adapter, cmd);
@@ -3534,6 +3536,7 @@ static inline int qlcnic_83xx_check_mbx_status(struct qlcnic_adapter *adapter)
 
 	host_mbx_ctrl = QLCRDX(ahw, QLCNIC_HOST_MBX_CTRL);
 	if (host_mbx_ctrl) {
+		clear_bit(QLC_83XX_MBX_READY, &mbx->status);
 		ahw->idc.collect_dump = 1;
 		return -EIO;
 	}
@@ -3704,8 +3707,10 @@ static void qlcnic_83xx_mailbox_worker(struct work_struct *work)
 	ahw = adapter->ahw;
 
 	while (true) {
-		if (qlcnic_83xx_check_mbx_status(adapter))
+		if (qlcnic_83xx_check_mbx_status(adapter)) {
+			qlcnic_83xx_flush_mbx_queue(adapter);
 			return;
+		}
 
 		atomic_set(rsp_status, QLC_83XX_MBX_RESPONSE_WAIT);