linux-kernel - [PATCH net 3/4] net: hns3: fix one incorrect value of page pool info when queried by debugfs

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Message-ID: <20211126120318.33921-4-huangguangbin2@huawei.com>
Date:   Fri, 26 Nov 2021 20:03:17 +0800
From:   Guangbin Huang <huangguangbin2@...wei.com>
To:     <davem@...emloft.net>, <kuba@...nel.org>, <wangjie125@...wei.com>
CC:     <netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <lipeng321@...wei.com>, <huangguangbin2@...wei.com>,
        <chenhao288@...ilicon.com>
Subject: [PATCH net 3/4] net: hns3: fix one incorrect value of page pool info when queried by debugfs

From: Hao Chen <chenhao288@...ilicon.com>

Currently, when user queries page pool info by debugfs command
"cat page_pool_info", the cnt of allocated page for page pool may be
incorrect because of memory inconsistency problem caused by compiler
optimization.

So this patch uses READ_ONCE() to read value of pages_state_hold_cnt to
fix this problem.

Fixes: 850bfb912a6d ("net: hns3: debugfs add support dumping page pool info")
Signed-off-by: Hao Chen <chenhao288@...ilicon.com>
Signed-off-by: Guangbin Huang <huangguangbin2@...wei.com>
---
 drivers/net/ethernet/hisilicon/hns3/hns3_debugfs.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/hisilicon/hns3/hns3_debugfs.c b/drivers/net/ethernet/hisilicon/hns3/hns3_debugfs.c
index fbb8a5f08222..081295bff765 100644
--- a/drivers/net/ethernet/hisilicon/hns3/hns3_debugfs.c
+++ b/drivers/net/ethernet/hisilicon/hns3/hns3_debugfs.c
@@ -1081,7 +1081,8 @@ static void hns3_dump_page_pool_info(struct hns3_enet_ring *ring,
 	u32 j = 0;
 
 	sprintf(result[j++], "%u", index);
-	sprintf(result[j++], "%u", ring->page_pool->pages_state_hold_cnt);
+	sprintf(result[j++], "%u",
+		READ_ONCE(ring->page_pool->pages_state_hold_cnt));
 	sprintf(result[j++], "%u",
 		atomic_read(&ring->page_pool->pages_state_release_cnt));
 	sprintf(result[j++], "%u", ring->page_pool->p.pool_size);
-- 
2.33.0