netdev - [PATCH AUTOSEL 4.19 170/237] net: hns3: bugfix for is_valid_csq_clean

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Date:   Sat, 16 Nov 2019 10:40:05 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Huazhong Tan <tanhuazhong@...wei.com>,
        "David S . Miller" <davem@...emloft.net>,
        Sasha Levin <sashal@...nel.org>, netdev@...r.kernel.org
Subject: [PATCH AUTOSEL 4.19 170/237] net: hns3: bugfix for is_valid_csq_clean_head()

From: Huazhong Tan <tanhuazhong@...wei.com>

[ Upstream commit 6d71ec6cbf74ac9c2823ef751b1baa5b889bb3ac ]

The HEAD pointer of the hardware command queue maybe equal to the command
queue's next_to_use in the driver, so that does not belong to the invalid
HEAD pointer, since the hardware may not process the command in time,
causing the HEAD pointer to be too late to update. The variables' name
in this function is unreadable, so give them a more readable one.

Fixes: 3ff504908f95 ("net: hns3: fix a dead loop in hclge_cmd_csq_clean")
Signed-off-by: Huazhong Tan <tanhuazhong@...wei.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 .../net/ethernet/hisilicon/hns3/hns3pf/hclge_cmd.c   | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/net/ethernet/hisilicon/hns3/hns3pf/hclge_cmd.c b/drivers/net/ethernet/hisilicon/hns3/hns3pf/hclge_cmd.c
index 68026a5ad7e77..690f62ed87dca 100644
--- a/drivers/net/ethernet/hisilicon/hns3/hns3pf/hclge_cmd.c
+++ b/drivers/net/ethernet/hisilicon/hns3/hns3pf/hclge_cmd.c
@@ -24,15 +24,15 @@ static int hclge_ring_space(struct hclge_cmq_ring *ring)
 	return ring->desc_num - used - 1;
 }
 
-static int is_valid_csq_clean_head(struct hclge_cmq_ring *ring, int h)
+static int is_valid_csq_clean_head(struct hclge_cmq_ring *ring, int head)
 {
-	int u = ring->next_to_use;
-	int c = ring->next_to_clean;
+	int ntu = ring->next_to_use;
+	int ntc = ring->next_to_clean;
 
-	if (unlikely(h >= ring->desc_num))
-		return 0;
+	if (ntu > ntc)
+		return head >= ntc && head <= ntu;
 
-	return u > c ? (h > c && h <= u) : (h > c || h <= u);
+	return head >= ntc || head <= ntu;
 }
 
 static int hclge_alloc_cmd_desc(struct hclge_cmq_ring *ring)
-- 
2.20.1