net: hns3: use appropriate barrier function after setting a bit value

There is a memory barrier in followed case. When set the port down,
hclgevf_set_timmer will set DOWN in state. Meanwhile, the service task has
different behaviour based on whether the state is DOWN. Thus, to make sure
service task see DOWN, use smp_mb__after_atomic after calling set_bit().

          CPU0                        CPU1
========================== ===================================
hclgevf_set_timer_task()    hclgevf_periodic_service_task()
  set_bit(DOWN,state)         test_bit(DOWN,state)

pf also has this issue.

Fixes: ff20009 ("net: hns3: remove unnecessary work in hclgevf_main")
Fixes: 1c6dfe6 ("net: hns3: remove mailbox and reset work in hclge_main")
Signed-off-by: Peiyang Wang <wangpeiyang1@huawei.com>
Signed-off-by: Jijie Shao <shaojijie@huawei.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

Author: Peiyang Wang

drivers/net/ethernet/hisilicon/hns3/hns3pf/hclge_main.c

@@ -7957,8 +7957,7 @@ static void hclge_set_timer_task(struct hnae3_handle *handle, bool enable)
 		/* Set the DOWN flag here to disable link updating */
 		set_bit(HCLGE_STATE_DOWN, &hdev->state);
 
-		/* flush memory to make sure DOWN is seen by service task */
-		smp_mb__before_atomic();
+		smp_mb__after_atomic(); /* flush memory to make sure DOWN is seen by service task */
 		hclge_flush_link_update(hdev);
 	}
 }

drivers/net/ethernet/hisilicon/hns3/hns3vf/hclgevf_main.c

@@ -2181,8 +2181,7 @@ static void hclgevf_set_timer_task(struct hnae3_handle *handle, bool enable)
 	} else {
 		set_bit(HCLGEVF_STATE_DOWN, &hdev->state);
 
-		/* flush memory to make sure DOWN is seen by service task */
-		smp_mb__before_atomic();
+		smp_mb__after_atomic(); /* flush memory to make sure DOWN is seen by service task */
 		hclgevf_flush_link_update(hdev);
 	}
 }