netdev - [Patch V2 net 06/11] net: hns3: bugfix for is_valid_csq_clean

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Date:   Sat, 27 Oct 2018 16:10:13 +0800
From:   Huazhong Tan <tanhuazhong@...wei.com>
To:     <davem@...emloft.net>
CC:     <netdev@...r.kernel.org>, <linuxarm@...wei.com>,
        <salil.mehta@...wei.com>, <yisen.zhuang@...wei.com>,
        <lipeng321@...wei.com>, <linyunsheng@...wei.com>
Subject: [Patch V2 net 06/11] net: hns3: bugfix for is_valid_csq_clean_head()

The HEAD pointer of the hardware command queue maybe equal to the command
queue's next_to_use 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>
---
 drivers/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 68026a5..690f62e 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)
-- 
2.7.4