linux-kernel - [PATCH v2] net: sched: sch_netem: Refactor code in 4-state loss generator

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Message-Id: <20211112213647.18062-1-harshit.m.mogalapalli@oracle.com>
Date:   Fri, 12 Nov 2021 13:36:47 -0800
From:   Harshit Mogalapalli <harshit.m.mogalapalli@...cle.com>
To:     unlisted-recipients:; (no To-header on input)
Cc:     harshit.m.mogalapalli@...cle.com,
        Stephen Hemminger <stephen@...workplumber.org>,
        Jamal Hadi Salim <jhs@...atatu.com>,
        Cong Wang <xiyou.wangcong@...il.com>,
        Jiri Pirko <jiri@...nulli.us>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Yang Yingliang <yangyingliang@...wei.com>,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v2] net: sched: sch_netem: Refactor code in 4-state loss generator

Fixed comments to match description with variable names and
refactored code to match the convention as per [1].

To match the convention mapping is done as follows:
State 3 - LOST_IN_BURST_PERIOD
State 4 - LOST_IN_GAP_PERIOD

[1] S. Salsano, F. Ludovici, A. Ordine, "Definition of a general
and intuitive loss model for packet networks and its implementation
in the Netem module in the Linux kernel"

Fixes: a6e2fe17eba4 ("sch_netem: replace magic numbers with enumerate")
Signed-off-by: Harshit Mogalapalli <harshit.m.mogalapalli@...cle.com>
---
 net/sched/sch_netem.c | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/net/sched/sch_netem.c b/net/sched/sch_netem.c
index ecbb10db1111..ed4ccef5d6a8 100644
--- a/net/sched/sch_netem.c
+++ b/net/sched/sch_netem.c
@@ -208,17 +208,17 @@ static bool loss_4state(struct netem_sched_data *q)
 	 * next state and if the next packet has to be transmitted or lost.
 	 * The four states correspond to:
 	 *   TX_IN_GAP_PERIOD => successfully transmitted packets within a gap period
-	 *   LOST_IN_BURST_PERIOD => isolated losses within a gap period
-	 *   LOST_IN_GAP_PERIOD => lost packets within a burst period
-	 *   TX_IN_GAP_PERIOD => successfully transmitted packets within a burst period
+	 *   LOST_IN_GAP_PERIOD => isolated losses within a gap period
+	 *   LOST_IN_BURST_PERIOD => lost packets within a burst period
+	 *   TX_IN_BURST_PERIOD => successfully transmitted packets within a burst period
 	 */
 	switch (clg->state) {
 	case TX_IN_GAP_PERIOD:
 		if (rnd < clg->a4) {
-			clg->state = LOST_IN_BURST_PERIOD;
+			clg->state = LOST_IN_GAP_PERIOD;
 			return true;
 		} else if (clg->a4 < rnd && rnd < clg->a1 + clg->a4) {
-			clg->state = LOST_IN_GAP_PERIOD;
+			clg->state = LOST_IN_BURST_PERIOD;
 			return true;
 		} else if (clg->a1 + clg->a4 < rnd) {
 			clg->state = TX_IN_GAP_PERIOD;
@@ -227,24 +227,24 @@ static bool loss_4state(struct netem_sched_data *q)
 		break;
 	case TX_IN_BURST_PERIOD:
 		if (rnd < clg->a5) {
-			clg->state = LOST_IN_GAP_PERIOD;
+			clg->state = LOST_IN_BURST_PERIOD;
 			return true;
 		} else {
 			clg->state = TX_IN_BURST_PERIOD;
 		}
 
 		break;
-	case LOST_IN_GAP_PERIOD:
+	case LOST_IN_BURST_PERIOD:
 		if (rnd < clg->a3)
 			clg->state = TX_IN_BURST_PERIOD;
 		else if (clg->a3 < rnd && rnd < clg->a2 + clg->a3) {
 			clg->state = TX_IN_GAP_PERIOD;
 		} else if (clg->a2 + clg->a3 < rnd) {
-			clg->state = LOST_IN_GAP_PERIOD;
+			clg->state = LOST_IN_BURST_PERIOD;
 			return true;
 		}
 		break;
-	case LOST_IN_BURST_PERIOD:
+	case LOST_IN_GAP_PERIOD:
 		clg->state = TX_IN_GAP_PERIOD;
 		break;
 	}
-- 
2.27.0