[dpdk-stable] [PATCH] latency: clear mbuf timestamp after latency calculation

[longtb5 at viettel.com.vn]

The timestamp of a mbuf should be cleared after that mbuf was used for
latency calculation, otherwise future packets which reuse the same mbuf
would inherit that previous timestamp. The latencystats library looks
for mbuf with non-zero timestamp, thus incorrectly inherited value would
result in incorrect latency measurement.

Cc: stable at dpdk.org

Signed-off-by: Bao-Long Tran <longtb5 at viettel.com.vn>
---
 lib/librte_latencystats/rte_latencystats.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/lib/librte_latencystats/rte_latencystats.c b/lib/librte_latencystats/rte_latencystats.c
index 1fdec68..2d5384e 100644
--- a/lib/librte_latencystats/rte_latencystats.c
+++ b/lib/librte_latencystats/rte_latencystats.c
@@ -156,8 +156,10 @@ calc_latency(uint16_t pid __rte_unused,
 
 	now = rte_rdtsc();
 	for (i = 0; i < nb_pkts; i++) {
-		if (pkts[i]->timestamp)
+		if (pkts[i]->timestamp) {
 			latency[cnt++] = now - pkts[i]->timestamp;
+			pkts[i]->timestamp = 0;
+		}
 	}
 
 	for (i = 0; i < cnt; i++) {
-- 
2.7.4