Commit cb3ef7b0 authored by Harshit Mogalapalli's avatar Harshit Mogalapalli Committed by David S. Miller
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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: a6e2fe17 ("sch_netem: replace magic numbers with enumerate")
Signed-off-by: default avatarHarshit Mogalapalli <harshit.m.mogalapalli@oracle.com>
Acked-by: default avatarStephen Hemminger <stephen@networkplumber.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent e99fa423

net/sched/sch_netem.c

+9 −9
Original line number Diff line number Diff line
@@ -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;

	}