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A sorted flow list is only needed to drop packets in the biggest flow when hitting the overmemory condition. By scanning flows only when needed, we can avoid paying the cost of maintaining the list under normal conditions In order to avoid scanning lots of empty flows and touching too many cold cache lines, a bitmap of flows with backlog is maintained Signed-off-by: Felix Fietkau <nbd@nbd.name> Link: https://lore.kernel.org/r/20201218184718.93650-3-nbd@nbd.name Signed-off-by: Johannes Berg <johannes.berg@intel.com>
391 lines
7.9 KiB
C
391 lines
7.9 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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* Copyright (c) 2016 Qualcomm Atheros, Inc
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*
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* Based on net/sched/sch_fq_codel.c
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*/
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#ifndef __NET_SCHED_FQ_IMPL_H
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#define __NET_SCHED_FQ_IMPL_H
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#include <net/fq.h>
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/* functions that are embedded into includer */
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static void
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__fq_adjust_removal(struct fq *fq, struct fq_flow *flow, unsigned int packets,
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unsigned int bytes, unsigned int truesize)
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{
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struct fq_tin *tin = flow->tin;
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int idx;
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tin->backlog_bytes -= bytes;
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tin->backlog_packets -= packets;
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flow->backlog -= bytes;
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fq->backlog -= packets;
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fq->memory_usage -= truesize;
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if (flow->backlog)
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return;
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if (flow == &tin->default_flow) {
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list_del_init(&tin->tin_list);
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return;
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}
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idx = flow - fq->flows;
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__clear_bit(idx, fq->flows_bitmap);
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}
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static void fq_adjust_removal(struct fq *fq,
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struct fq_flow *flow,
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struct sk_buff *skb)
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{
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__fq_adjust_removal(fq, flow, 1, skb->len, skb->truesize);
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}
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static struct sk_buff *fq_flow_dequeue(struct fq *fq,
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struct fq_flow *flow)
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{
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struct sk_buff *skb;
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lockdep_assert_held(&fq->lock);
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skb = __skb_dequeue(&flow->queue);
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if (!skb)
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return NULL;
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fq_adjust_removal(fq, flow, skb);
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return skb;
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}
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static int fq_flow_drop(struct fq *fq, struct fq_flow *flow,
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fq_skb_free_t free_func)
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{
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unsigned int packets = 0, bytes = 0, truesize = 0;
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struct fq_tin *tin = flow->tin;
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struct sk_buff *skb;
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int pending;
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lockdep_assert_held(&fq->lock);
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pending = min_t(int, 32, skb_queue_len(&flow->queue) / 2);
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do {
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skb = __skb_dequeue(&flow->queue);
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if (!skb)
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break;
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packets++;
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bytes += skb->len;
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truesize += skb->truesize;
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free_func(fq, tin, flow, skb);
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} while (packets < pending);
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__fq_adjust_removal(fq, flow, packets, bytes, truesize);
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return packets;
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}
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static struct sk_buff *fq_tin_dequeue(struct fq *fq,
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struct fq_tin *tin,
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fq_tin_dequeue_t dequeue_func)
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{
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struct fq_flow *flow;
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struct list_head *head;
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struct sk_buff *skb;
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lockdep_assert_held(&fq->lock);
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begin:
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head = &tin->new_flows;
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if (list_empty(head)) {
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head = &tin->old_flows;
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if (list_empty(head))
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return NULL;
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}
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flow = list_first_entry(head, struct fq_flow, flowchain);
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if (flow->deficit <= 0) {
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flow->deficit += fq->quantum;
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list_move_tail(&flow->flowchain,
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&tin->old_flows);
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goto begin;
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}
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skb = dequeue_func(fq, tin, flow);
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if (!skb) {
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/* force a pass through old_flows to prevent starvation */
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if ((head == &tin->new_flows) &&
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!list_empty(&tin->old_flows)) {
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list_move_tail(&flow->flowchain, &tin->old_flows);
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} else {
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list_del_init(&flow->flowchain);
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flow->tin = NULL;
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}
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goto begin;
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}
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flow->deficit -= skb->len;
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tin->tx_bytes += skb->len;
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tin->tx_packets++;
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return skb;
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}
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static u32 fq_flow_idx(struct fq *fq, struct sk_buff *skb)
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{
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u32 hash = skb_get_hash(skb);
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return reciprocal_scale(hash, fq->flows_cnt);
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}
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static struct fq_flow *fq_flow_classify(struct fq *fq,
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struct fq_tin *tin, u32 idx,
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struct sk_buff *skb)
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{
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struct fq_flow *flow;
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lockdep_assert_held(&fq->lock);
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flow = &fq->flows[idx];
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if (flow->tin && flow->tin != tin) {
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flow = &tin->default_flow;
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tin->collisions++;
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fq->collisions++;
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}
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if (!flow->tin)
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tin->flows++;
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return flow;
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}
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static struct fq_flow *fq_find_fattest_flow(struct fq *fq)
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{
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struct fq_tin *tin;
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struct fq_flow *flow = NULL;
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u32 len = 0;
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int i;
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for_each_set_bit(i, fq->flows_bitmap, fq->flows_cnt) {
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struct fq_flow *cur = &fq->flows[i];
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unsigned int cur_len;
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cur_len = cur->backlog;
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if (cur_len <= len)
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continue;
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flow = cur;
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len = cur_len;
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}
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list_for_each_entry(tin, &fq->tin_backlog, tin_list) {
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unsigned int cur_len = tin->default_flow.backlog;
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if (cur_len <= len)
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continue;
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flow = &tin->default_flow;
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len = cur_len;
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}
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return flow;
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}
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static void fq_tin_enqueue(struct fq *fq,
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struct fq_tin *tin, u32 idx,
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struct sk_buff *skb,
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fq_skb_free_t free_func)
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{
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struct fq_flow *flow;
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bool oom;
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lockdep_assert_held(&fq->lock);
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flow = fq_flow_classify(fq, tin, idx, skb);
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if (!flow->backlog) {
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if (flow != &tin->default_flow)
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__set_bit(idx, fq->flows_bitmap);
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else if (list_empty(&tin->tin_list))
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list_add(&tin->tin_list, &fq->tin_backlog);
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}
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flow->tin = tin;
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flow->backlog += skb->len;
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tin->backlog_bytes += skb->len;
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tin->backlog_packets++;
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fq->memory_usage += skb->truesize;
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fq->backlog++;
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if (list_empty(&flow->flowchain)) {
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flow->deficit = fq->quantum;
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list_add_tail(&flow->flowchain,
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&tin->new_flows);
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}
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__skb_queue_tail(&flow->queue, skb);
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oom = (fq->memory_usage > fq->memory_limit);
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while (fq->backlog > fq->limit || oom) {
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flow = fq_find_fattest_flow(fq);
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if (!flow)
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return;
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if (!fq_flow_drop(fq, flow, free_func))
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return;
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flow->tin->overlimit++;
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fq->overlimit++;
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if (oom) {
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fq->overmemory++;
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oom = (fq->memory_usage > fq->memory_limit);
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}
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}
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}
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static void fq_flow_filter(struct fq *fq,
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struct fq_flow *flow,
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fq_skb_filter_t filter_func,
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void *filter_data,
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fq_skb_free_t free_func)
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{
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struct fq_tin *tin = flow->tin;
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struct sk_buff *skb, *tmp;
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lockdep_assert_held(&fq->lock);
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skb_queue_walk_safe(&flow->queue, skb, tmp) {
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if (!filter_func(fq, tin, flow, skb, filter_data))
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continue;
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__skb_unlink(skb, &flow->queue);
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fq_adjust_removal(fq, flow, skb);
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free_func(fq, tin, flow, skb);
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}
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}
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static void fq_tin_filter(struct fq *fq,
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struct fq_tin *tin,
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fq_skb_filter_t filter_func,
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void *filter_data,
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fq_skb_free_t free_func)
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{
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struct fq_flow *flow;
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lockdep_assert_held(&fq->lock);
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list_for_each_entry(flow, &tin->new_flows, flowchain)
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fq_flow_filter(fq, flow, filter_func, filter_data, free_func);
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list_for_each_entry(flow, &tin->old_flows, flowchain)
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fq_flow_filter(fq, flow, filter_func, filter_data, free_func);
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}
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static void fq_flow_reset(struct fq *fq,
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struct fq_flow *flow,
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fq_skb_free_t free_func)
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{
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struct fq_tin *tin = flow->tin;
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struct sk_buff *skb;
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while ((skb = fq_flow_dequeue(fq, flow)))
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free_func(fq, tin, flow, skb);
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if (!list_empty(&flow->flowchain)) {
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list_del_init(&flow->flowchain);
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if (list_empty(&tin->new_flows) &&
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list_empty(&tin->old_flows))
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list_del_init(&tin->tin_list);
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}
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flow->tin = NULL;
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WARN_ON_ONCE(flow->backlog);
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}
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static void fq_tin_reset(struct fq *fq,
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struct fq_tin *tin,
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fq_skb_free_t free_func)
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{
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struct list_head *head;
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struct fq_flow *flow;
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for (;;) {
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head = &tin->new_flows;
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if (list_empty(head)) {
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head = &tin->old_flows;
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if (list_empty(head))
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break;
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}
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flow = list_first_entry(head, struct fq_flow, flowchain);
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fq_flow_reset(fq, flow, free_func);
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}
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WARN_ON_ONCE(!list_empty(&tin->tin_list));
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WARN_ON_ONCE(tin->backlog_bytes);
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WARN_ON_ONCE(tin->backlog_packets);
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}
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static void fq_flow_init(struct fq_flow *flow)
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{
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INIT_LIST_HEAD(&flow->flowchain);
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__skb_queue_head_init(&flow->queue);
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}
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static void fq_tin_init(struct fq_tin *tin)
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{
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INIT_LIST_HEAD(&tin->new_flows);
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INIT_LIST_HEAD(&tin->old_flows);
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INIT_LIST_HEAD(&tin->tin_list);
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fq_flow_init(&tin->default_flow);
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}
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static int fq_init(struct fq *fq, int flows_cnt)
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{
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int i;
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memset(fq, 0, sizeof(fq[0]));
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spin_lock_init(&fq->lock);
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INIT_LIST_HEAD(&fq->tin_backlog);
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fq->flows_cnt = max_t(u32, flows_cnt, 1);
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fq->quantum = 300;
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fq->limit = 8192;
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fq->memory_limit = 16 << 20; /* 16 MBytes */
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fq->flows = kvcalloc(fq->flows_cnt, sizeof(fq->flows[0]), GFP_KERNEL);
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if (!fq->flows)
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return -ENOMEM;
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fq->flows_bitmap = kcalloc(BITS_TO_LONGS(fq->flows_cnt), sizeof(long),
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GFP_KERNEL);
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if (!fq->flows_bitmap) {
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kvfree(fq->flows);
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fq->flows = NULL;
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return -ENOMEM;
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}
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for (i = 0; i < fq->flows_cnt; i++)
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fq_flow_init(&fq->flows[i]);
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return 0;
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}
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static void fq_reset(struct fq *fq,
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fq_skb_free_t free_func)
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{
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int i;
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for (i = 0; i < fq->flows_cnt; i++)
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fq_flow_reset(fq, &fq->flows[i], free_func);
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kvfree(fq->flows);
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fq->flows = NULL;
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kfree(fq->flows_bitmap);
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fq->flows_bitmap = NULL;
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}
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#endif
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