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Commit 843cacb8 authored by Eric Dumazet's avatar Eric Dumazet Committed by Greg Kroah-Hartman
Browse files

net_sched: sch_sfq: handle bigger packets 



[ Upstream commit e4650d7ae4252f67e997a632adfae0dd74d3a99a ]

SFQ has an assumption on dealing with packets smaller than 64KB.

Even before BIG TCP, TCA_STAB can provide arbitrary big values
in qdisc_pkt_len(skb)

It is time to switch (struct sfq_slot)->allot to a 32bit field.

sizeof(struct sfq_slot) is now 64 bytes, giving better cache locality.

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Reviewed-by: default avatarToke Høiland-Jørgensen <toke@redhat.com>
Link: https://patch.msgid.link/20241008111603.653140-1-edumazet@google.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
Signed-off-by: default avatarHarshit Mogalapalli <harshit.m.mogalapalli@oracle.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 74d5d257

net/sched/sch_sfq.c

+13 −26
Original line number Diff line number Diff line
@@ -77,12 +77,6 @@ 
#define SFQ_EMPTY_SLOT		0xffff

#define SFQ_DEFAULT_HASH_DIVISOR 1024



/* We use 16 bits to store allot, and want to handle packets up to 64K

 * Scale allot by 8 (1<<3) so that no overflow occurs.

 */

#define SFQ_ALLOT_SHIFT		3

#define SFQ_ALLOT_SIZE(X)	DIV_ROUND_UP(X, 1 << SFQ_ALLOT_SHIFT)



/* This type should contain at least SFQ_MAX_DEPTH + 1 + SFQ_MAX_FLOWS values */

typedef u16 sfq_index;
@@ -104,7 +98,7 @@ struct sfq_slot { 
	sfq_index	next; /* next slot in sfq RR chain */

	struct sfq_head dep; /* anchor in dep[] chains */

	unsigned short	hash; /* hash value (index in ht[]) */

	short		allot; /* credit for this slot */

	int		allot; /* credit for this slot */



	unsigned int    backlog;

	struct red_vars vars;
@@ -120,7 +114,6 @@ struct sfq_sched_data { 
	siphash_key_t 	perturbation;

	u8		cur_depth;	/* depth of longest slot */

	u8		flags;

	unsigned short  scaled_quantum; /* SFQ_ALLOT_SIZE(quantum) */

	struct tcf_proto __rcu *filter_list;

	struct tcf_block *block;

	sfq_index	*ht;		/* Hash table ('divisor' slots) */
@@ -459,7 +452,7 @@ sfq_enqueue(struct sk_buff *skb, struct Qdisc *sch, struct sk_buff **to_free) 
		 */

		q->tail = slot;

		/* We could use a bigger initial quantum for new flows */

		slot->allot = q->scaled_quantum;

		slot->allot = q->quantum;

	}

	if (++sch->q.qlen <= q->limit)

		return NET_XMIT_SUCCESS;
@@ -496,7 +489,7 @@ sfq_dequeue(struct Qdisc *sch) 
	slot = &q->slots[a];

	if (slot->allot <= 0) {

		q->tail = slot;

		slot->allot += q->scaled_quantum;

		slot->allot += q->quantum;

		goto next_slot;

	}

	skb = slot_dequeue_head(slot);
@@ -515,7 +508,7 @@ sfq_dequeue(struct Qdisc *sch) 
		}

		q->tail->next = next_a;

	} else {

		slot->allot -= SFQ_ALLOT_SIZE(qdisc_pkt_len(skb));

		slot->allot -= qdisc_pkt_len(skb);

	}

	return skb;

}
@@ -598,7 +591,7 @@ static void sfq_rehash(struct Qdisc *sch) 
				q->tail->next = x;

			}

			q->tail = slot;

			slot->allot = q->scaled_quantum;

			slot->allot = q->quantum;

		}

	}

	sch->q.qlen -= dropped;
@@ -628,7 +621,8 @@ static void sfq_perturbation(struct timer_list *t) 
		mod_timer(&q->perturb_timer, jiffies + period);

}



static int sfq_change(struct Qdisc *sch, struct nlattr *opt)

static int sfq_change(struct Qdisc *sch, struct nlattr *opt,

		      struct netlink_ext_ack *extack)

{

	struct sfq_sched_data *q = qdisc_priv(sch);

	struct tc_sfq_qopt *ctl = nla_data(opt);
@@ -646,14 +640,10 @@ static int sfq_change(struct Qdisc *sch, struct nlattr *opt) 
	    (!is_power_of_2(ctl->divisor) || ctl->divisor > 65536))

		return -EINVAL;



	/* slot->allot is a short, make sure quantum is not too big. */

	if (ctl->quantum) {

		unsigned int scaled = SFQ_ALLOT_SIZE(ctl->quantum);



		if (scaled <= 0 || scaled > SHRT_MAX)

	if ((int)ctl->quantum < 0) {

		NL_SET_ERR_MSG_MOD(extack, "invalid quantum");

		return -EINVAL;

	}



	if (ctl_v1 && !red_check_params(ctl_v1->qth_min, ctl_v1->qth_max,

					ctl_v1->Wlog, ctl_v1->Scell_log, NULL))

		return -EINVAL;
@@ -663,10 +653,8 @@ static int sfq_change(struct Qdisc *sch, struct nlattr *opt) 
			return -ENOMEM;

	}

	sch_tree_lock(sch);

	if (ctl->quantum) {

	if (ctl->quantum)

		q->quantum = ctl->quantum;

		q->scaled_quantum = SFQ_ALLOT_SIZE(q->quantum);

	}

	WRITE_ONCE(q->perturb_period, ctl->perturb_period * HZ);

	if (ctl->flows)

		q->maxflows = min_t(u32, ctl->flows, SFQ_MAX_FLOWS);
@@ -762,12 +750,11 @@ static int sfq_init(struct Qdisc *sch, struct nlattr *opt, 
	q->divisor = SFQ_DEFAULT_HASH_DIVISOR;

	q->maxflows = SFQ_DEFAULT_FLOWS;

	q->quantum = psched_mtu(qdisc_dev(sch));

	q->scaled_quantum = SFQ_ALLOT_SIZE(q->quantum);

	q->perturb_period = 0;

	get_random_bytes(&q->perturbation, sizeof(q->perturbation));



	if (opt) {

		int err = sfq_change(sch, opt);

		int err = sfq_change(sch, opt, extack);

		if (err)

			return err;

	}
@@ -878,7 +865,7 @@ static int sfq_dump_class_stats(struct Qdisc *sch, unsigned long cl, 
	if (idx != SFQ_EMPTY_SLOT) {

		const struct sfq_slot *slot = &q->slots[idx];



		xstats.allot = slot->allot << SFQ_ALLOT_SHIFT;

		xstats.allot = slot->allot;

		qs.qlen = slot->qlen;

		qs.backlog = slot->backlog;

	}