From: Huazhong Tan <tanhuazhong@huawei.com>
Date: Tue, 30 Oct 2018 21:50:48 +0800
Subject: net: hns3: bugfix for is_valid_csq_clean_head()
Patch-mainline: v4.20-rc1
Git-commit: 6d71ec6cbf74ac9c2823ef751b1baa5b889bb3ac
References: bsc#1104353 FATE#326415

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@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 drivers/net/ethernet/hisilicon/hns3/hns3pf/hclge_cmd.c |   12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

--- 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
 	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)