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Commit 4976e3c6 authored by Toke Høiland-Jørgensen's avatar Toke Høiland-Jørgensen Committed by David S. Miller
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sch_cake: Simplify logic in cake_select_tin() 



With more modes added the logic in cake_select_tin() was getting a bit
hairy, and it turns out we can actually simplify it quite a bit. This also
allows us to get rid of one of the two diffserv parsing functions, which
has the added benefit that already-zeroed DSCP fields won't get re-written.

Suggested-by: default avatarKevin Darbyshire-Bryant <ldir@darbyshire-bryant.me.uk>
Signed-off-by: default avatarToke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 0b5c7efd

net/sched/sch_cake.c

+23 −38
Original line number Diff line number Diff line
@@ -1513,20 +1513,6 @@ static unsigned int cake_drop(struct Qdisc *sch, struct sk_buff **to_free) 
	return idx + (tin << 16);

}



static void cake_wash_diffserv(struct sk_buff *skb)

{

	switch (skb->protocol) {

	case htons(ETH_P_IP):

		ipv4_change_dsfield(ip_hdr(skb), INET_ECN_MASK, 0);

		break;

	case htons(ETH_P_IPV6):

		ipv6_change_dsfield(ipv6_hdr(skb), INET_ECN_MASK, 0);

		break;

	default:

		break;

	}

}



static u8 cake_handle_diffserv(struct sk_buff *skb, u16 wash)

{

	u8 dscp;
@@ -1558,34 +1544,33 @@ static struct cake_tin_data *cake_select_tin(struct Qdisc *sch, 
{

	struct cake_sched_data *q = qdisc_priv(sch);

	u32 tin;

	u8 dscp;



	if (TC_H_MAJ(skb->priority) == sch->handle &&

	    TC_H_MIN(skb->priority) > 0 &&

	    TC_H_MIN(skb->priority) <= q->tin_cnt) {

		tin = q->tin_order[TC_H_MIN(skb->priority) - 1];

	/* Tin selection: Default to diffserv-based selection, allow overriding

	 * using firewall marks or skb->priority.

	 */

	dscp = cake_handle_diffserv(skb,

				    q->rate_flags & CAKE_FLAG_WASH);



		if (q->rate_flags & CAKE_FLAG_WASH)

			cake_wash_diffserv(skb);

	} else if (q->tin_mode != CAKE_DIFFSERV_BESTEFFORT) {

		if (q->rate_flags & CAKE_FLAG_FWMARK && /* use fw mark */

	if (q->tin_mode == CAKE_DIFFSERV_BESTEFFORT)

		tin = 0;



	else if (q->rate_flags & CAKE_FLAG_FWMARK && /* use fw mark */

		 skb->mark &&

		    skb->mark <= q->tin_cnt) {

		 skb->mark <= q->tin_cnt)

		tin = q->tin_order[skb->mark - 1];

			if (q->rate_flags & CAKE_FLAG_WASH)

				cake_wash_diffserv(skb);

		} else {

			/* extract the Diffserv Precedence field, if it exists */

			/* and clear DSCP bits if washing */

			tin = q->tin_index[cake_handle_diffserv(skb,

					q->rate_flags & CAKE_FLAG_WASH)];



	else if (TC_H_MAJ(skb->priority) == sch->handle &&

		 TC_H_MIN(skb->priority) > 0 &&

		 TC_H_MIN(skb->priority) <= q->tin_cnt)

		tin = q->tin_order[TC_H_MIN(skb->priority) - 1];



	else {

		tin = q->tin_index[dscp];



		if (unlikely(tin >= q->tin_cnt))

			tin = 0;

	}

	} else {

		tin = 0;

		if (q->rate_flags & CAKE_FLAG_WASH)

			cake_wash_diffserv(skb);

	}



	return &q->tins[tin];

}