linux-kernel - [PATCH net 4/7] net: hns3: use appropriate barrier function after setting a bit value

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Date: Mon, 22 Apr 2024 21:43:24 +0800
From: Jijie Shao <shaojijie@...wei.com>
To: <yisen.zhuang@...wei.com>, <salil.mehta@...wei.com>,
	<davem@...emloft.net>, <edumazet@...gle.com>, <kuba@...nel.org>,
	<pabeni@...hat.com>
CC: <shenjian15@...wei.com>, <wangjie125@...wei.com>,
	<liuyonglong@...wei.com>, <shaojijie@...wei.com>, <chenhao418@...wei.com>,
	<netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: [PATCH net 4/7] net: hns3: use appropriate barrier function after setting a bit value

From: Peiyang Wang <wangpeiyang1@...wei.com>

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: ff200099d271 ("net: hns3: remove unnecessary work in hclgevf_main")
Fixes: 1c6dfe6fc6f7 ("net: hns3: remove mailbox and reset work in hclge_main")
Signed-off-by: Peiyang Wang <wangpeiyang1@...wei.com>
Signed-off-by: Jijie Shao <shaojijie@...wei.com>
---
 drivers/net/ethernet/hisilicon/hns3/hns3pf/hclge_main.c   | 3 +--
 drivers/net/ethernet/hisilicon/hns3/hns3vf/hclgevf_main.c | 3 +--
 2 files changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/hisilicon/hns3/hns3pf/hclge_main.c b/drivers/net/ethernet/hisilicon/hns3/hns3pf/hclge_main.c
index a068cd745eb4..6eda73f1e6ad 100644
--- a/drivers/net/ethernet/hisilicon/hns3/hns3pf/hclge_main.c
+++ b/drivers/net/ethernet/hisilicon/hns3/hns3pf/hclge_main.c
@@ -7954,8 +7954,7 @@ 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);
 	}
 }
diff --git a/drivers/net/ethernet/hisilicon/hns3/hns3vf/hclgevf_main.c b/drivers/net/ethernet/hisilicon/hns3/hns3vf/hclgevf_main.c
index b57111252d07..08db8e84be4e 100644
--- a/drivers/net/ethernet/hisilicon/hns3/hns3vf/hclgevf_main.c
+++ b/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);
 	}
 }
-- 
2.30.0