[dpdk-dev] [PATCH 04/12] net/hns3: fix potentially incorrect timing in MBX

[Min Hu (Connor)]

From: Chengchang Tang <tangchengchang at huawei.com>

Currently, when processing MBX messages, the system timestamp is obtained
to determine whether timeout occurs. However, the gettimeofday function
is not monotonically increasing. Therefore, this may lead to incorrect
judgment or difficulty exiting the loop. And actually, in this scenario,
it is not necessary to obatain the timestamp.

This patch deletes the call to the gettimeofday function during MBX
message processing.

Fixes: 463e748964f5 ("net/hns3: support mailbox")
Cc: stable at dpdk.org

Signed-off-by: Chengchang Tang <tangchengchang at huawei.com>
Signed-off-by: Min Hu (Connor) <humin29 at huawei.com>
---
 drivers/net/hns3/hns3_mbx.c | 13 +++++--------
 1 file changed, 5 insertions(+), 8 deletions(-)

diff --git a/drivers/net/hns3/hns3_mbx.c b/drivers/net/hns3/hns3_mbx.c
index c5b0856..eb202dd 100644
--- a/drivers/net/hns3/hns3_mbx.c
+++ b/drivers/net/hns3/hns3_mbx.c
@@ -61,13 +61,12 @@ static int
 hns3_get_mbx_resp(struct hns3_hw *hw, uint16_t code, uint16_t subcode,
 		  uint8_t *resp_data, uint16_t resp_len)
 {
-#define HNS3_MAX_RETRY_MS	500
+#define HNS3_MAX_RETRY_US	500000
 #define HNS3_WAIT_RESP_US	100
 	struct hns3_adapter *hns = HNS3_DEV_HW_TO_ADAPTER(hw);
 	struct hns3_mbx_resp_status *mbx_resp;
+	uint32_t wait_time = 0;
 	bool received;
-	uint64_t now;
-	uint64_t end;
 
 	if (resp_len > HNS3_MBX_MAX_RESP_DATA_SIZE) {
 		hns3_err(hw, "VF mbx response len(=%u) exceeds maximum(=%d)",
@@ -75,9 +74,7 @@ hns3_get_mbx_resp(struct hns3_hw *hw, uint16_t code, uint16_t subcode,
 		return -EINVAL;
 	}
 
-	now = get_timeofday_ms();
-	end = now + HNS3_MAX_RETRY_MS;
-	while (now < end) {
+	while (wait_time < HNS3_MAX_RETRY_US) {
 		if (__atomic_load_n(&hw->reset.disable_cmd, __ATOMIC_RELAXED)) {
 			hns3_err(hw, "Don't wait for mbx respone because of "
 				 "disable_cmd");
@@ -103,10 +100,10 @@ hns3_get_mbx_resp(struct hns3_hw *hw, uint16_t code, uint16_t subcode,
 		if (received)
 			break;
 
-		now = get_timeofday_ms();
+		wait_time += HNS3_WAIT_RESP_US;
 	}
 	hw->mbx_resp.req_msg_data = 0;
-	if (now >= end) {
+	if (wait_time >= HNS3_MAX_RETRY_US) {
 		hns3_mbx_proc_timeout(hw, code, subcode);
 		return -ETIME;
 	}
-- 
2.7.4