include/net/fq_impl.h

   1 /*
   2  * Copyright (c) 2016 Qualcomm Atheros, Inc
   3  *
   4  * GPL v2
   5  *
   6  * Based on net/sched/sch_fq_codel.c
   7  */
   8 #ifndef __NET_SCHED_FQ_IMPL_H
   9 #define __NET_SCHED_FQ_IMPL_H
  10
  11 #include <net/fq.h>
  12
  13 /* functions that are embedded into includer */
  14
  15 static struct sk_buff *fq_flow_dequeue(struct fq *fq,
  16                                        struct fq_flow *flow)
  17 {
  18         struct fq_tin *tin = flow->tin;
  19         struct fq_flow *i;
  20         struct sk_buff *skb;
  21
  22         lockdep_assert_held(&fq->lock);
  23
  24         skb = __skb_dequeue(&flow->queue);
  25         if (!skb)
  26                 return NULL;
  27
  28         tin->backlog_bytes -= skb->len;
  29         tin->backlog_packets--;
  30         flow->backlog -= skb->len;
  31         fq->backlog--;
  32         fq->memory_usage -= skb->truesize;
  33
  34         if (flow->backlog == 0) {
  35                 list_del_init(&flow->backlogchain);
  36         } else {
  37                 i = flow;
  38
  39                 list_for_each_entry_continue(i, &fq->backlogs, backlogchain)
  40                         if (i->backlog < flow->backlog)
  41                                 break;
  42
  43                 list_move_tail(&flow->backlogchain,
  44                                &i->backlogchain);
  45         }
  46
  47         return skb;
  48 }
  49
  50 static struct sk_buff *fq_tin_dequeue(struct fq *fq,
  51                                       struct fq_tin *tin,
  52                                       fq_tin_dequeue_t dequeue_func)
  53 {
  54         struct fq_flow *flow;
  55         struct list_head *head;
  56         struct sk_buff *skb;
  57
  58         lockdep_assert_held(&fq->lock);
  59
  60 begin:
  61         head = &tin->new_flows;
  62         if (list_empty(head)) {
  63                 head = &tin->old_flows;
  64                 if (list_empty(head))
  65                         return NULL;
  66         }
  67
  68         flow = list_first_entry(head, struct fq_flow, flowchain);
  69
  70         if (flow->deficit <= 0) {
  71                 flow->deficit += fq->quantum;
  72                 list_move_tail(&flow->flowchain,
  73                                &tin->old_flows);
  74                 goto begin;
  75         }
  76
  77         skb = dequeue_func(fq, tin, flow);
  78         if (!skb) {
  79                 /* force a pass through old_flows to prevent starvation */
  80                 if ((head == &tin->new_flows) &&
  81                     !list_empty(&tin->old_flows)) {
  82                         list_move_tail(&flow->flowchain, &tin->old_flows);
  83                 } else {
  84                         list_del_init(&flow->flowchain);
  85                         flow->tin = NULL;
  86                 }
  87                 goto begin;
  88         }
  89
  90         flow->deficit -= skb->len;
  91         tin->tx_bytes += skb->len;
  92         tin->tx_packets++;
  93
  94         return skb;
  95 }
  96
  97 static struct fq_flow *fq_flow_classify(struct fq *fq,
  98                                         struct fq_tin *tin,
  99                                         struct sk_buff *skb,
 100                                         fq_flow_get_default_t get_default_func)
 101 {
 102         struct fq_flow *flow;
 103         u32 hash;
 104         u32 idx;
 105
 106         lockdep_assert_held(&fq->lock);
 107
 108         hash = skb_get_hash_perturb(skb, fq->perturbation);
 109         idx = reciprocal_scale(hash, fq->flows_cnt);
 110         flow = &fq->flows[idx];
 111
 112         if (flow->tin && flow->tin != tin) {
 113                 flow = get_default_func(fq, tin, idx, skb);
 114                 tin->collisions++;
 115                 fq->collisions++;
 116         }
 117
 118         if (!flow->tin)
 119                 tin->flows++;
 120
 121         return flow;
 122 }
 123
 124 static void fq_recalc_backlog(struct fq *fq,
 125                               struct fq_tin *tin,
 126                               struct fq_flow *flow)
 127 {
 128         struct fq_flow *i;
 129
 130         if (list_empty(&flow->backlogchain))
 131                 list_add_tail(&flow->backlogchain, &fq->backlogs);
 132
 133         i = flow;
 134         list_for_each_entry_continue_reverse(i, &fq->backlogs,
 135                                              backlogchain)
 136                 if (i->backlog > flow->backlog)
 137                         break;
 138
 139         list_move(&flow->backlogchain, &i->backlogchain);
 140 }
 141
 142 static void fq_tin_enqueue(struct fq *fq,
 143                            struct fq_tin *tin,
 144                            struct sk_buff *skb,
 145                            fq_skb_free_t free_func,
 146                            fq_flow_get_default_t get_default_func)
 147 {
 148         struct fq_flow *flow;
 149         bool oom;
 150
 151         lockdep_assert_held(&fq->lock);
 152
 153         flow = fq_flow_classify(fq, tin, skb, get_default_func);
 154
 155         flow->tin = tin;
 156         flow->backlog += skb->len;
 157         tin->backlog_bytes += skb->len;
 158         tin->backlog_packets++;
 159         fq->memory_usage += skb->truesize;
 160         fq->backlog++;
 161
 162         fq_recalc_backlog(fq, tin, flow);
 163
 164         if (list_empty(&flow->flowchain)) {
 165                 flow->deficit = fq->quantum;
 166                 list_add_tail(&flow->flowchain,
 167                               &tin->new_flows);
 168         }
 169
 170         __skb_queue_tail(&flow->queue, skb);
 171         oom = (fq->memory_usage > fq->memory_limit);
 172         while (fq->backlog > fq->limit || oom) {
 173                 flow = list_first_entry_or_null(&fq->backlogs,
 174                                                 struct fq_flow,
 175                                                 backlogchain);
 176                 if (!flow)
 177                         return;
 178
 179                 skb = fq_flow_dequeue(fq, flow);
 180                 if (!skb)
 181                         return;
 182
 183                 free_func(fq, flow->tin, flow, skb);
 184
 185                 flow->tin->overlimit++;
 186                 fq->overlimit++;
 187                 if (oom) {
 188                         fq->overmemory++;
 189                         oom = (fq->memory_usage > fq->memory_limit);
 190                 }
 191         }
 192 }
 193
 194 static void fq_flow_reset(struct fq *fq,
 195                           struct fq_flow *flow,
 196                           fq_skb_free_t free_func)
 197 {
 198         struct sk_buff *skb;
 199
 200         while ((skb = fq_flow_dequeue(fq, flow)))
 201                 free_func(fq, flow->tin, flow, skb);
 202
 203         if (!list_empty(&flow->flowchain))
 204                 list_del_init(&flow->flowchain);
 205
 206         if (!list_empty(&flow->backlogchain))
 207                 list_del_init(&flow->backlogchain);
 208
 209         flow->tin = NULL;
 210
 211         WARN_ON_ONCE(flow->backlog);
 212 }
 213
 214 static void fq_tin_reset(struct fq *fq,
 215                          struct fq_tin *tin,
 216                          fq_skb_free_t free_func)
 217 {
 218         struct list_head *head;
 219         struct fq_flow *flow;
 220
 221         for (;;) {
 222                 head = &tin->new_flows;
 223                 if (list_empty(head)) {
 224                         head = &tin->old_flows;
 225                         if (list_empty(head))
 226                                 break;
 227                 }
 228
 229                 flow = list_first_entry(head, struct fq_flow, flowchain);
 230                 fq_flow_reset(fq, flow, free_func);
 231         }
 232
 233         WARN_ON_ONCE(tin->backlog_bytes);
 234         WARN_ON_ONCE(tin->backlog_packets);
 235 }
 236
 237 static void fq_flow_init(struct fq_flow *flow)
 238 {
 239         INIT_LIST_HEAD(&flow->flowchain);
 240         INIT_LIST_HEAD(&flow->backlogchain);
 241         __skb_queue_head_init(&flow->queue);
 242 }
 243
 244 static void fq_tin_init(struct fq_tin *tin)
 245 {
 246         INIT_LIST_HEAD(&tin->new_flows);
 247         INIT_LIST_HEAD(&tin->old_flows);
 248 }
 249
 250 static int fq_init(struct fq *fq, int flows_cnt)
 251 {
 252         int i;
 253
 254         memset(fq, 0, sizeof(fq[0]));
 255         INIT_LIST_HEAD(&fq->backlogs);
 256         spin_lock_init(&fq->lock);
 257         fq->flows_cnt = max_t(u32, flows_cnt, 1);
 258         fq->perturbation = prandom_u32();
 259         fq->quantum = 300;
 260         fq->limit = 8192;
 261         fq->memory_limit = 16 << 20; /* 16 MBytes */
 262
 263         fq->flows = kcalloc(fq->flows_cnt, sizeof(fq->flows[0]), GFP_KERNEL);
 264         if (!fq->flows)
 265                 return -ENOMEM;
 266
 267         for (i = 0; i < fq->flows_cnt; i++)
 268                 fq_flow_init(&fq->flows[i]);
 269
 270         return 0;
 271 }
 272
 273 static void fq_reset(struct fq *fq,
 274                      fq_skb_free_t free_func)
 275 {
 276         int i;
 277
 278         for (i = 0; i < fq->flows_cnt; i++)
 279                 fq_flow_reset(fq, &fq->flows[i], free_func);
 280
 281         kfree(fq->flows);
 282         fq->flows = NULL;
 283 }
 284
 285 #endif