net: hns3: add a check to pointer in error_detected and slot_reset

If we add a VF without loading hclgevf.ko and then there is a RAS error
occurs, PCIe AER will call error_detected and slot_reset of all functions,
and will get a NULL pointer when we check ad_dev->ops->handle_hw_ras_error.
This will cause a call trace and failures on handling of follow-up RAS
errors.

This patch check ae_dev and ad_dev->ops at first to solve above issues.
Signed-off-by: Weihang Li <liweihang@hisilicon.com>
Signed-off-by: Peng Li <lipeng321@huawei.com>
Signed-off-by: Huazhong Tan <tanhuazhong@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/hisilicon/hns3/hns3_enet.c

@@ -1920,9 +1920,9 @@ static pci_ers_result_t hns3_error_detected(struct pci_dev *pdev,
 	if (state == pci_channel_io_perm_failure)
 		return PCI_ERS_RESULT_DISCONNECT;
 
-	if (!ae_dev) {
+	if (!ae_dev || !ae_dev->ops) {
 		dev_err(&pdev->dev,
-			"Can't recover - error happened during device init\n");
+			"Can't recover - error happened before device initialized\n");
 		return PCI_ERS_RESULT_NONE;
 	}
 
@@ -1941,6 +1941,9 @@ static pci_ers_result_t hns3_slot_reset(struct pci_dev *pdev)
 
 	dev_info(dev, "requesting reset due to PCI error\n");
 
+	if (!ae_dev || !ae_dev->ops)
+		return PCI_ERS_RESULT_NONE;
+
 	/* request the reset */
 	if (ae_dev->ops->reset_event) {
 		if (!ae_dev->override_pci_need_reset)