net/sctp/stream_sched_rr.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /* SCTP kernel implementation
   3  * (C) Copyright Red Hat Inc. 2017
   4  *
   5  * This file is part of the SCTP kernel implementation
   6  *
   7  * These functions manipulate sctp stream queue/scheduling.
   8  *
   9  * Please send any bug reports or fixes you make to the
  10  * email addresched(es):
  11  *    lksctp developers <linux-sctp@vger.kernel.org>
  12  *
  13  * Written or modified by:
  14  *    Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
  15  */
  16
  17 #include <linux/list.h>
  18 #include <net/sctp/sctp.h>
  19 #include <net/sctp/sm.h>
  20 #include <net/sctp/stream_sched.h>
  21
  22 /* Priority handling
  23  * RFC DRAFT ndata section 3.2
  24  */
  25 static void sctp_sched_rr_unsched_all(struct sctp_stream *stream);
  26
  27 static void sctp_sched_rr_next_stream(struct sctp_stream *stream)
  28 {
  29         struct list_head *pos;
  30
  31         pos = stream->rr_next->rr_list.next;
  32         if (pos == &stream->rr_list)
  33                 pos = pos->next;
  34         stream->rr_next = list_entry(pos, struct sctp_stream_out_ext, rr_list);
  35 }
  36
  37 static void sctp_sched_rr_unsched(struct sctp_stream *stream,
  38                                   struct sctp_stream_out_ext *soute)
  39 {
  40         if (stream->rr_next == soute)
  41                 /* Try to move to the next stream */
  42                 sctp_sched_rr_next_stream(stream);
  43
  44         list_del_init(&soute->rr_list);
  45
  46         /* If we have no other stream queued, clear next */
  47         if (list_empty(&stream->rr_list))
  48                 stream->rr_next = NULL;
  49 }
  50
  51 static void sctp_sched_rr_sched(struct sctp_stream *stream,
  52                                 struct sctp_stream_out_ext *soute)
  53 {
  54         if (!list_empty(&soute->rr_list))
  55                 /* Already scheduled. */
  56                 return;
  57
  58         /* Schedule the stream */
  59         list_add_tail(&soute->rr_list, &stream->rr_list);
  60
  61         if (!stream->rr_next)
  62                 stream->rr_next = soute;
  63 }
  64
  65 static int sctp_sched_rr_set(struct sctp_stream *stream, __u16 sid,
  66                              __u16 prio, gfp_t gfp)
  67 {
  68         return 0;
  69 }
  70
  71 static int sctp_sched_rr_get(struct sctp_stream *stream, __u16 sid,
  72                              __u16 *value)
  73 {
  74         return 0;
  75 }
  76
  77 static int sctp_sched_rr_init(struct sctp_stream *stream)
  78 {
  79         INIT_LIST_HEAD(&stream->rr_list);
  80         stream->rr_next = NULL;
  81
  82         return 0;
  83 }
  84
  85 static int sctp_sched_rr_init_sid(struct sctp_stream *stream, __u16 sid,
  86                                   gfp_t gfp)
  87 {
  88         INIT_LIST_HEAD(&SCTP_SO(stream, sid)->ext->rr_list);
  89
  90         return 0;
  91 }
  92
  93 static void sctp_sched_rr_free(struct sctp_stream *stream)
  94 {
  95         sctp_sched_rr_unsched_all(stream);
  96 }
  97
  98 static void sctp_sched_rr_enqueue(struct sctp_outq *q,
  99                                   struct sctp_datamsg *msg)
 100 {
 101         struct sctp_stream *stream;
 102         struct sctp_chunk *ch;
 103         __u16 sid;
 104
 105         ch = list_first_entry(&msg->chunks, struct sctp_chunk, frag_list);
 106         sid = sctp_chunk_stream_no(ch);
 107         stream = &q->asoc->stream;
 108         sctp_sched_rr_sched(stream, SCTP_SO(stream, sid)->ext);
 109 }
 110
 111 static struct sctp_chunk *sctp_sched_rr_dequeue(struct sctp_outq *q)
 112 {
 113         struct sctp_stream *stream = &q->asoc->stream;
 114         struct sctp_stream_out_ext *soute;
 115         struct sctp_chunk *ch = NULL;
 116
 117         /* Bail out quickly if queue is empty */
 118         if (list_empty(&q->out_chunk_list))
 119                 goto out;
 120
 121         /* Find which chunk is next */
 122         if (stream->out_curr)
 123                 soute = stream->out_curr->ext;
 124         else
 125                 soute = stream->rr_next;
 126         ch = list_entry(soute->outq.next, struct sctp_chunk, stream_list);
 127
 128         sctp_sched_dequeue_common(q, ch);
 129
 130 out:
 131         return ch;
 132 }
 133
 134 static void sctp_sched_rr_dequeue_done(struct sctp_outq *q,
 135                                        struct sctp_chunk *ch)
 136 {
 137         struct sctp_stream_out_ext *soute;
 138         __u16 sid;
 139
 140         /* Last chunk on that msg, move to the next stream */
 141         sid = sctp_chunk_stream_no(ch);
 142         soute = SCTP_SO(&q->asoc->stream, sid)->ext;
 143
 144         sctp_sched_rr_next_stream(&q->asoc->stream);
 145
 146         if (list_empty(&soute->outq))
 147                 sctp_sched_rr_unsched(&q->asoc->stream, soute);
 148 }
 149
 150 static void sctp_sched_rr_sched_all(struct sctp_stream *stream)
 151 {
 152         struct sctp_association *asoc;
 153         struct sctp_stream_out_ext *soute;
 154         struct sctp_chunk *ch;
 155
 156         asoc = container_of(stream, struct sctp_association, stream);
 157         list_for_each_entry(ch, &asoc->outqueue.out_chunk_list, list) {
 158                 __u16 sid;
 159
 160                 sid = sctp_chunk_stream_no(ch);
 161                 soute = SCTP_SO(stream, sid)->ext;
 162                 if (soute)
 163                         sctp_sched_rr_sched(stream, soute);
 164         }
 165 }
 166
 167 static void sctp_sched_rr_unsched_all(struct sctp_stream *stream)
 168 {
 169         struct sctp_stream_out_ext *soute, *tmp;
 170
 171         list_for_each_entry_safe(soute, tmp, &stream->rr_list, rr_list)
 172                 sctp_sched_rr_unsched(stream, soute);
 173 }
 174
 175 static struct sctp_sched_ops sctp_sched_rr = {
 176         .set = sctp_sched_rr_set,
 177         .get = sctp_sched_rr_get,
 178         .init = sctp_sched_rr_init,
 179         .init_sid = sctp_sched_rr_init_sid,
 180         .free = sctp_sched_rr_free,
 181         .enqueue = sctp_sched_rr_enqueue,
 182         .dequeue = sctp_sched_rr_dequeue,
 183         .dequeue_done = sctp_sched_rr_dequeue_done,
 184         .sched_all = sctp_sched_rr_sched_all,
 185         .unsched_all = sctp_sched_rr_unsched_all,
 186 };
 187
 188 void sctp_sched_ops_rr_init(void)
 189 {
 190         sctp_sched_ops_register(SCTP_SS_RR, &sctp_sched_rr);
 191 }