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Commit a6e2fe17 authored by Yang Yingliang's avatar Yang Yingliang Committed by David S. Miller
Browse files

sch_netem: replace magic numbers with enumerate 



Replace some magic numbers which describe states of 4-state model
loss generator with enumerate.

Signed-off-by: default avatarYang Yingliang <yangyingliang@huawei.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 6444f72b

net/sched/sch_netem.c

+28 −19
Original line number Diff line number Diff line
@@ -110,6 +110,13 @@ struct netem_sched_data { 
		CLG_GILB_ELL,

	} loss_model;



	enum {

		TX_IN_GAP_PERIOD = 1,

		TX_IN_BURST_PERIOD,

		LOST_IN_GAP_PERIOD,

		LOST_IN_BURST_PERIOD,

	} _4_state_model;



	/* Correlated Loss Generation models */

	struct clgstate {

		/* state of the Markov chain */
@@ -205,43 +212,45 @@ static bool loss_4state(struct netem_sched_data *q) 
	 * probabilities outgoing from the current state, then decides the

	 * next state and if the next packet has to be transmitted or lost.

	 * The four states correspond to:

	 *   1 => successfully transmitted packets within a gap period

	 *   4 => isolated losses within a gap period

	 *   3 => lost packets within a burst period

	 *   2 => successfully transmitted packets within a burst period

	 *   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

	 */

	switch (clg->state) {

	case 1:

	case TX_IN_GAP_PERIOD:

		if (rnd < clg->a4) {

			clg->state = 4;

			clg->state = LOST_IN_BURST_PERIOD;

			return true;

		} else if (clg->a4 < rnd && rnd < clg->a1 + clg->a4) {

			clg->state = 3;

			clg->state = LOST_IN_GAP_PERIOD;

			return true;

		} else if (clg->a1 + clg->a4 < rnd)

			clg->state = 1;

		} else if (clg->a1 + clg->a4 < rnd) {

			clg->state = TX_IN_GAP_PERIOD;

		}



		break;

	case 2:

	case TX_IN_BURST_PERIOD:

		if (rnd < clg->a5) {

			clg->state = 3;

			clg->state = LOST_IN_GAP_PERIOD;

			return true;

		} else

			clg->state = 2;

		} else {

			clg->state = TX_IN_BURST_PERIOD;

		}



		break;

	case 3:

	case LOST_IN_GAP_PERIOD:

		if (rnd < clg->a3)

			clg->state = 2;

			clg->state = TX_IN_BURST_PERIOD;

		else if (clg->a3 < rnd && rnd < clg->a2 + clg->a3) {

			clg->state = 1;

			clg->state = TX_IN_GAP_PERIOD;

		} else if (clg->a2 + clg->a3 < rnd) {

			clg->state = 3;

			clg->state = LOST_IN_GAP_PERIOD;

			return true;

		}

		break;

	case 4:

		clg->state = 1;

	case LOST_IN_BURST_PERIOD:

		clg->state = TX_IN_GAP_PERIOD;

		break;

	}