commit e4650d7ae4252f67e997a632adfae0dd74d3a99a upstream.
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: Eric Dumazet edumazet@google.com Reviewed-by: Toke Høiland-Jørgensen toke@redhat.com Link: https://patch.msgid.link/20241008111603.653140-1-edumazet@google.com Signed-off-by: Jakub Kicinski kuba@kernel.org --- net/sched/sch_sfq.c | 39 +++++++++++++-------------------------- 1 file changed, 13 insertions(+), 26 deletions(-)
diff --git a/net/sched/sch_sfq.c b/net/sched/sch_sfq.c index d6299eb12a8164bcaa0594d3ac2829531bfac588..714bdc2c5a682a9767ce5e8a404aa7b4889604a6 100644 --- a/net/sched/sch_sfq.c +++ b/net/sched/sch_sfq.c @@ -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) */ @@ -456,7 +449,7 @@ 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; @@ -493,7 +486,7 @@ 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); @@ -512,7 +505,7 @@ 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; } @@ -595,7 +588,7 @@ 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; @@ -625,7 +618,8 @@ 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); @@ -643,14 +637,10 @@ 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) - return -EINVAL; + 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; @@ -660,10 +650,8 @@ 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); @@ -759,12 +747,11 @@ 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; } @@ -875,7 +862,7 @@ 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; }