crypto: hisilicon/qm - flush all work before driver removed

Before removing the driver, flush inter-function communication
work, and subsequent communication work is not processed.
This prevents communication threads from accessing released memory.

Fixes: ("crypto: hisilicon/qm - enable PF and VFs communication")
Signed-off-by: Weili Qian <qianweili@huawei.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

drivers/crypto/hisilicon/qm.c

@@ -954,6 +954,11 @@ static irqreturn_t qm_mb_cmd_irq(int irq, void *data)
 	if (!val)
 		return IRQ_NONE;
 
+	if (test_bit(QM_DRIVER_REMOVING, &qm->misc_ctl)) {
+		dev_warn(&qm->pdev->dev, "Driver is down, message cannot be processed!\n");
+		return IRQ_HANDLED;
+	}
+
 	schedule_work(&qm->cmd_process);
 
 	return IRQ_HANDLED;
@@ -2743,6 +2748,9 @@ void hisi_qm_wait_task_finish(struct hisi_qm *qm, struct hisi_qm_list *qm_list)
 	       test_bit(QM_RESETTING, &qm->misc_ctl))
 		msleep(WAIT_PERIOD);
 
+	if (test_bit(QM_SUPPORT_MB_COMMAND, &qm->caps))
+		flush_work(&qm->cmd_process);
+
 	udelay(REMOVE_WAIT_DELAY);
 }
 EXPORT_SYMBOL_GPL(hisi_qm_wait_task_finish);