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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: Kevin Darbyshire-Bryant <ldir@darbyshire-bryant.me.uk>
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
hifive-unleashed-5.1
Toke Høiland-Jørgensen 2019-03-01 16:04:05 +01:00 committed by David S. Miller
parent 0b5c7efdfc
commit 4976e3c683
1 changed files with 23 additions and 38 deletions
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61
net/sched/sch_cake.c
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@ -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;
@ -1558,33 +1544,32 @@ 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 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->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)
tin = q->tin_order[skb->mark - 1];
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];
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 */
skb->mark &&
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)];
if (unlikely(tin >= q->tin_cnt))
tin = 0;
}
} else {
tin = 0;
if (q->rate_flags & CAKE_FLAG_WASH)
cake_wash_diffserv(skb);
else {
tin = q->tin_index[dscp];
if (unlikely(tin >= q->tin_cnt))
tin = 0;
}
return &q->tins[tin];