net/mac80211/mesh_ps.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright 2012-2013, Marco Porsch <marco.porsch@s2005.tu-chemnitz.de>
   4  * Copyright 2012-2013, cozybit Inc.
   5  * Copyright (C) 2021 Intel Corporation
   6  * Copyright (C) 2023 Intel Corporation
   7  */
   8
   9 #include "mesh.h"
  10 #include "wme.h"
  11
  12
  13 /* mesh PS management */
  14
  15 /**
  16  * mps_qos_null_get - create pre-addressed QoS Null frame for mesh powersave
  17  * @sta: the station to get the frame for
  18  *
  19  * Returns: A newly allocated SKB
  20  */
  21 static struct sk_buff *mps_qos_null_get(struct sta_info *sta)
  22 {
  23         struct ieee80211_sub_if_data *sdata = sta->sdata;
  24         struct ieee80211_local *local = sdata->local;
  25         struct ieee80211_hdr *nullfunc; /* use 4addr header */
  26         struct sk_buff *skb;
  27         int size = sizeof(*nullfunc);
  28         __le16 fc;
  29
  30         skb = dev_alloc_skb(local->hw.extra_tx_headroom + size + 2);
  31         if (!skb)
  32                 return NULL;
  33         skb_reserve(skb, local->hw.extra_tx_headroom);
  34
  35         nullfunc = skb_put(skb, size);
  36         fc = cpu_to_le16(IEEE80211_FTYPE_DATA | IEEE80211_STYPE_QOS_NULLFUNC);
  37         ieee80211_fill_mesh_addresses(nullfunc, &fc, sta->sta.addr,
  38                                       sdata->vif.addr);
  39         nullfunc->frame_control = fc;
  40         nullfunc->duration_id = 0;
  41         nullfunc->seq_ctrl = 0;
  42         /* no address resolution for this frame -> set addr 1 immediately */
  43         memcpy(nullfunc->addr1, sta->sta.addr, ETH_ALEN);
  44         skb_put_zero(skb, 2); /* append QoS control field */
  45         ieee80211_mps_set_frame_flags(sdata, sta, nullfunc);
  46
  47         return skb;
  48 }
  49
  50 /**
  51  * mps_qos_null_tx - send a QoS Null to indicate link-specific power mode
  52  * @sta: the station to send to
  53  */
  54 static void mps_qos_null_tx(struct sta_info *sta)
  55 {
  56         struct sk_buff *skb;
  57
  58         skb = mps_qos_null_get(sta);
  59         if (!skb)
  60                 return;
  61
  62         mps_dbg(sta->sdata, "announcing peer-specific power mode to %pM\n",
  63                 sta->sta.addr);
  64
  65         /* don't unintentionally start a MPSP */
  66         if (!test_sta_flag(sta, WLAN_STA_PS_STA)) {
  67                 u8 *qc = ieee80211_get_qos_ctl((void *) skb->data);
  68
  69                 qc[0] |= IEEE80211_QOS_CTL_EOSP;
  70         }
  71
  72         ieee80211_tx_skb(sta->sdata, skb);
  73 }
  74
  75 /**
  76  * ieee80211_mps_local_status_update - track status of local link-specific PMs
  77  *
  78  * @sdata: local mesh subif
  79  *
  80  * sets the non-peer power mode and triggers the driver PS (re-)configuration
  81  * Return BSS_CHANGED_BEACON if a beacon update is necessary.
  82  *
  83  * Returns: BSS_CHANGED_BEACON if a beacon update is in order.
  84  */
  85 u64 ieee80211_mps_local_status_update(struct ieee80211_sub_if_data *sdata)
  86 {
  87         struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
  88         struct sta_info *sta;
  89         bool peering = false;
  90         int light_sleep_cnt = 0;
  91         int deep_sleep_cnt = 0;
  92         u64 changed = 0;
  93         enum nl80211_mesh_power_mode nonpeer_pm;
  94
  95         rcu_read_lock();
  96         list_for_each_entry_rcu(sta, &sdata->local->sta_list, list) {
  97                 if (sdata != sta->sdata)
  98                         continue;
  99
 100                 switch (sta->mesh->plink_state) {
 101                 case NL80211_PLINK_OPN_SNT:
 102                 case NL80211_PLINK_OPN_RCVD:
 103                 case NL80211_PLINK_CNF_RCVD:
 104                         peering = true;
 105                         break;
 106                 case NL80211_PLINK_ESTAB:
 107                         if (sta->mesh->local_pm == NL80211_MESH_POWER_LIGHT_SLEEP)
 108                                 light_sleep_cnt++;
 109                         else if (sta->mesh->local_pm == NL80211_MESH_POWER_DEEP_SLEEP)
 110                                 deep_sleep_cnt++;
 111                         break;
 112                 default:
 113                         break;
 114                 }
 115         }
 116         rcu_read_unlock();
 117
 118         /*
 119          * Set non-peer mode to active during peering/scanning/authentication
 120          * (see IEEE802.11-2012 13.14.8.3). The non-peer mesh power mode is
 121          * deep sleep if the local STA is in light or deep sleep towards at
 122          * least one mesh peer (see 13.14.3.1). Otherwise, set it to the
 123          * user-configured default value.
 124          */
 125         if (peering) {
 126                 mps_dbg(sdata, "setting non-peer PM to active for peering\n");
 127                 nonpeer_pm = NL80211_MESH_POWER_ACTIVE;
 128         } else if (light_sleep_cnt || deep_sleep_cnt) {
 129                 mps_dbg(sdata, "setting non-peer PM to deep sleep\n");
 130                 nonpeer_pm = NL80211_MESH_POWER_DEEP_SLEEP;
 131         } else {
 132                 mps_dbg(sdata, "setting non-peer PM to user value\n");
 133                 nonpeer_pm = ifmsh->mshcfg.power_mode;
 134         }
 135
 136         /* need update if sleep counts move between 0 and non-zero */
 137         if (ifmsh->nonpeer_pm != nonpeer_pm ||
 138             !ifmsh->ps_peers_light_sleep != !light_sleep_cnt ||
 139             !ifmsh->ps_peers_deep_sleep != !deep_sleep_cnt)
 140                 changed = BSS_CHANGED_BEACON;
 141
 142         ifmsh->nonpeer_pm = nonpeer_pm;
 143         ifmsh->ps_peers_light_sleep = light_sleep_cnt;
 144         ifmsh->ps_peers_deep_sleep = deep_sleep_cnt;
 145
 146         return changed;
 147 }
 148
 149 /**
 150  * ieee80211_mps_set_sta_local_pm - set local PM towards a mesh STA
 151  *
 152  * @sta: mesh STA
 153  * @pm: the power mode to set
 154  * Returns: BSS_CHANGED_BEACON if a beacon update is in order.
 155  */
 156 u64 ieee80211_mps_set_sta_local_pm(struct sta_info *sta,
 157                                    enum nl80211_mesh_power_mode pm)
 158 {
 159         struct ieee80211_sub_if_data *sdata = sta->sdata;
 160
 161         if (sta->mesh->local_pm == pm)
 162                 return 0;
 163
 164         mps_dbg(sdata, "local STA operates in mode %d with %pM\n",
 165                 pm, sta->sta.addr);
 166
 167         sta->mesh->local_pm = pm;
 168
 169         /*
 170          * announce peer-specific power mode transition
 171          * (see IEEE802.11-2012 13.14.3.2 and 13.14.3.3)
 172          */
 173         if (sta->mesh->plink_state == NL80211_PLINK_ESTAB)
 174                 mps_qos_null_tx(sta);
 175
 176         return ieee80211_mps_local_status_update(sdata);
 177 }
 178
 179 /**
 180  * ieee80211_mps_set_frame_flags - set mesh PS flags in FC (and QoS Control)
 181  *
 182  * @sdata: local mesh subif
 183  * @sta: mesh STA
 184  * @hdr: 802.11 frame header
 185  *
 186  * see IEEE802.11-2012 8.2.4.1.7 and 8.2.4.5.11
 187  *
 188  * NOTE: sta must be given when an individually-addressed QoS frame header
 189  * is handled, for group-addressed and management frames it is not used
 190  */
 191 void ieee80211_mps_set_frame_flags(struct ieee80211_sub_if_data *sdata,
 192                                    struct sta_info *sta,
 193                                    struct ieee80211_hdr *hdr)
 194 {
 195         enum nl80211_mesh_power_mode pm;
 196         u8 *qc;
 197
 198         if (WARN_ON(is_unicast_ether_addr(hdr->addr1) &&
 199                     ieee80211_is_data_qos(hdr->frame_control) &&
 200                     !sta))
 201                 return;
 202
 203         if (is_unicast_ether_addr(hdr->addr1) &&
 204             ieee80211_is_data_qos(hdr->frame_control) &&
 205             sta->mesh->plink_state == NL80211_PLINK_ESTAB)
 206                 pm = sta->mesh->local_pm;
 207         else
 208                 pm = sdata->u.mesh.nonpeer_pm;
 209
 210         if (pm == NL80211_MESH_POWER_ACTIVE)
 211                 hdr->frame_control &= cpu_to_le16(~IEEE80211_FCTL_PM);
 212         else
 213                 hdr->frame_control |= cpu_to_le16(IEEE80211_FCTL_PM);
 214
 215         if (!ieee80211_is_data_qos(hdr->frame_control))
 216                 return;
 217
 218         qc = ieee80211_get_qos_ctl(hdr);
 219
 220         if ((is_unicast_ether_addr(hdr->addr1) &&
 221              pm == NL80211_MESH_POWER_DEEP_SLEEP) ||
 222             (is_multicast_ether_addr(hdr->addr1) &&
 223              sdata->u.mesh.ps_peers_deep_sleep > 0))
 224                 qc[1] |= (IEEE80211_QOS_CTL_MESH_PS_LEVEL >> 8);
 225         else
 226                 qc[1] &= ~(IEEE80211_QOS_CTL_MESH_PS_LEVEL >> 8);
 227 }
 228
 229 /**
 230  * ieee80211_mps_sta_status_update - update buffering status of neighbor STA
 231  *
 232  * @sta: mesh STA
 233  *
 234  * called after change of peering status or non-peer/peer-specific power mode
 235  */
 236 void ieee80211_mps_sta_status_update(struct sta_info *sta)
 237 {
 238         enum nl80211_mesh_power_mode pm;
 239         bool do_buffer;
 240
 241         /* For non-assoc STA, prevent buffering or frame transmission */
 242         if (sta->sta_state < IEEE80211_STA_ASSOC)
 243                 return;
 244
 245         /*
 246          * use peer-specific power mode if peering is established and the
 247          * peer's power mode is known
 248          */
 249         if (sta->mesh->plink_state == NL80211_PLINK_ESTAB &&
 250             sta->mesh->peer_pm != NL80211_MESH_POWER_UNKNOWN)
 251                 pm = sta->mesh->peer_pm;
 252         else
 253                 pm = sta->mesh->nonpeer_pm;
 254
 255         do_buffer = (pm != NL80211_MESH_POWER_ACTIVE);
 256
 257         /* clear the MPSP flags for non-peers or active STA */
 258         if (sta->mesh->plink_state != NL80211_PLINK_ESTAB) {
 259                 clear_sta_flag(sta, WLAN_STA_MPSP_OWNER);
 260                 clear_sta_flag(sta, WLAN_STA_MPSP_RECIPIENT);
 261         } else if (!do_buffer) {
 262                 clear_sta_flag(sta, WLAN_STA_MPSP_OWNER);
 263         }
 264
 265         /* Don't let the same PS state be set twice */
 266         if (test_sta_flag(sta, WLAN_STA_PS_STA) == do_buffer)
 267                 return;
 268
 269         if (do_buffer) {
 270                 set_sta_flag(sta, WLAN_STA_PS_STA);
 271                 atomic_inc(&sta->sdata->u.mesh.ps.num_sta_ps);
 272                 mps_dbg(sta->sdata, "start PS buffering frames towards %pM\n",
 273                         sta->sta.addr);
 274         } else {
 275                 ieee80211_sta_ps_deliver_wakeup(sta);
 276         }
 277 }
 278
 279 static void mps_set_sta_peer_pm(struct sta_info *sta,
 280                                 struct ieee80211_hdr *hdr)
 281 {
 282         enum nl80211_mesh_power_mode pm;
 283         u8 *qc = ieee80211_get_qos_ctl(hdr);
 284
 285         /*
 286          * Test Power Management field of frame control (PW) and
 287          * mesh power save level subfield of QoS control field (PSL)
 288          *
 289          * | PM | PSL| Mesh PM |
 290          * +----+----+---------+
 291          * | 0  |Rsrv|  Active |
 292          * | 1  | 0  |  Light  |
 293          * | 1  | 1  |  Deep   |
 294          */
 295         if (ieee80211_has_pm(hdr->frame_control)) {
 296                 if (qc[1] & (IEEE80211_QOS_CTL_MESH_PS_LEVEL >> 8))
 297                         pm = NL80211_MESH_POWER_DEEP_SLEEP;
 298                 else
 299                         pm = NL80211_MESH_POWER_LIGHT_SLEEP;
 300         } else {
 301                 pm = NL80211_MESH_POWER_ACTIVE;
 302         }
 303
 304         if (sta->mesh->peer_pm == pm)
 305                 return;
 306
 307         mps_dbg(sta->sdata, "STA %pM enters mode %d\n",
 308                 sta->sta.addr, pm);
 309
 310         sta->mesh->peer_pm = pm;
 311
 312         ieee80211_mps_sta_status_update(sta);
 313 }
 314
 315 static void mps_set_sta_nonpeer_pm(struct sta_info *sta,
 316                                    struct ieee80211_hdr *hdr)
 317 {
 318         enum nl80211_mesh_power_mode pm;
 319
 320         if (ieee80211_has_pm(hdr->frame_control))
 321                 pm = NL80211_MESH_POWER_DEEP_SLEEP;
 322         else
 323                 pm = NL80211_MESH_POWER_ACTIVE;
 324
 325         if (sta->mesh->nonpeer_pm == pm)
 326                 return;
 327
 328         mps_dbg(sta->sdata, "STA %pM sets non-peer mode to %d\n",
 329                 sta->sta.addr, pm);
 330
 331         sta->mesh->nonpeer_pm = pm;
 332
 333         ieee80211_mps_sta_status_update(sta);
 334 }
 335
 336 /**
 337  * ieee80211_mps_rx_h_sta_process - frame receive handler for mesh powersave
 338  *
 339  * @sta: STA info that transmitted the frame
 340  * @hdr: IEEE 802.11 (QoS) Header
 341  */
 342 void ieee80211_mps_rx_h_sta_process(struct sta_info *sta,
 343                                     struct ieee80211_hdr *hdr)
 344 {
 345         if (is_unicast_ether_addr(hdr->addr1) &&
 346             ieee80211_is_data_qos(hdr->frame_control)) {
 347                 /*
 348                  * individually addressed QoS Data/Null frames contain
 349                  * peer link-specific PS mode towards the local STA
 350                  */
 351                 mps_set_sta_peer_pm(sta, hdr);
 352
 353                 /* check for mesh Peer Service Period trigger frames */
 354                 ieee80211_mpsp_trigger_process(ieee80211_get_qos_ctl(hdr),
 355                                                sta, false, false);
 356         } else {
 357                 /*
 358                  * can only determine non-peer PS mode
 359                  * (see IEEE802.11-2012 8.2.4.1.7)
 360                  */
 361                 mps_set_sta_nonpeer_pm(sta, hdr);
 362         }
 363 }
 364
 365
 366 /* mesh PS frame release */
 367
 368 static void mpsp_trigger_send(struct sta_info *sta, bool rspi, bool eosp)
 369 {
 370         struct ieee80211_sub_if_data *sdata = sta->sdata;
 371         struct sk_buff *skb;
 372         struct ieee80211_hdr *nullfunc;
 373         struct ieee80211_tx_info *info;
 374         u8 *qc;
 375
 376         skb = mps_qos_null_get(sta);
 377         if (!skb)
 378                 return;
 379
 380         nullfunc = (struct ieee80211_hdr *) skb->data;
 381         if (!eosp)
 382                 nullfunc->frame_control |=
 383                                 cpu_to_le16(IEEE80211_FCTL_MOREDATA);
 384         /*
 385          * | RSPI | EOSP |  MPSP triggering   |
 386          * +------+------+--------------------+
 387          * |  0   |  0   | local STA is owner |
 388          * |  0   |  1   | no MPSP (MPSP end) |
 389          * |  1   |  0   | both STA are owner |
 390          * |  1   |  1   | peer STA is owner  | see IEEE802.11-2012 13.14.9.2
 391          */
 392         qc = ieee80211_get_qos_ctl(nullfunc);
 393         if (rspi)
 394                 qc[1] |= (IEEE80211_QOS_CTL_RSPI >> 8);
 395         if (eosp)
 396                 qc[0] |= IEEE80211_QOS_CTL_EOSP;
 397
 398         info = IEEE80211_SKB_CB(skb);
 399
 400         info->flags |= IEEE80211_TX_CTL_NO_PS_BUFFER |
 401                        IEEE80211_TX_CTL_REQ_TX_STATUS;
 402
 403         mps_dbg(sdata, "sending MPSP trigger%s%s to %pM\n",
 404                 rspi ? " RSPI" : "", eosp ? " EOSP" : "", sta->sta.addr);
 405
 406         ieee80211_tx_skb(sdata, skb);
 407 }
 408
 409 /**
 410  * mpsp_qos_null_append - append QoS Null frame to MPSP skb queue if needed
 411  * @sta: the station to handle
 412  * @frames: the frame list to append to
 413  *
 414  * To properly end a mesh MPSP the last transmitted frame has to set the EOSP
 415  * flag in the QoS Control field. In case the current tailing frame is not a
 416  * QoS Data frame, append a QoS Null to carry the flag.
 417  */
 418 static void mpsp_qos_null_append(struct sta_info *sta,
 419                                  struct sk_buff_head *frames)
 420 {
 421         struct ieee80211_sub_if_data *sdata = sta->sdata;
 422         struct sk_buff *new_skb, *skb = skb_peek_tail(frames);
 423         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
 424         struct ieee80211_tx_info *info;
 425
 426         if (ieee80211_is_data_qos(hdr->frame_control))
 427                 return;
 428
 429         new_skb = mps_qos_null_get(sta);
 430         if (!new_skb)
 431                 return;
 432
 433         mps_dbg(sdata, "appending QoS Null in MPSP towards %pM\n",
 434                 sta->sta.addr);
 435         /*
 436          * This frame has to be transmitted last. Assign lowest priority to
 437          * make sure it cannot pass other frames when releasing multiple ACs.
 438          */
 439         new_skb->priority = 1;
 440         skb_set_queue_mapping(new_skb, IEEE80211_AC_BK);
 441         ieee80211_set_qos_hdr(sdata, new_skb);
 442
 443         info = IEEE80211_SKB_CB(new_skb);
 444         info->control.vif = &sdata->vif;
 445         info->control.flags |= IEEE80211_TX_INTCFL_NEED_TXPROCESSING;
 446
 447         __skb_queue_tail(frames, new_skb);
 448 }
 449
 450 /**
 451  * mps_frame_deliver - transmit frames during mesh powersave
 452  *
 453  * @sta: STA info to transmit to
 454  * @n_frames: number of frames to transmit. -1 for all
 455  */
 456 static void mps_frame_deliver(struct sta_info *sta, int n_frames)
 457 {
 458         struct ieee80211_local *local = sta->sdata->local;
 459         int ac;
 460         struct sk_buff_head frames;
 461         struct sk_buff *skb;
 462         bool more_data = false;
 463
 464         skb_queue_head_init(&frames);
 465
 466         /* collect frame(s) from buffers */
 467         for (ac = 0; ac < IEEE80211_NUM_ACS; ac++) {
 468                 while (n_frames != 0) {
 469                         skb = skb_dequeue(&sta->tx_filtered[ac]);
 470                         if (!skb) {
 471                                 skb = skb_dequeue(
 472                                         &sta->ps_tx_buf[ac]);
 473                                 if (skb)
 474                                         local->total_ps_buffered--;
 475                         }
 476                         if (!skb)
 477                                 break;
 478                         n_frames--;
 479                         __skb_queue_tail(&frames, skb);
 480                 }
 481
 482                 if (!skb_queue_empty(&sta->tx_filtered[ac]) ||
 483                     !skb_queue_empty(&sta->ps_tx_buf[ac]))
 484                         more_data = true;
 485         }
 486
 487         /* nothing to send? -> EOSP */
 488         if (skb_queue_empty(&frames)) {
 489                 mpsp_trigger_send(sta, false, true);
 490                 return;
 491         }
 492
 493         /* in a MPSP make sure the last skb is a QoS Data frame */
 494         if (test_sta_flag(sta, WLAN_STA_MPSP_OWNER))
 495                 mpsp_qos_null_append(sta, &frames);
 496
 497         mps_dbg(sta->sdata, "sending %d frames to PS STA %pM\n",
 498                 skb_queue_len(&frames), sta->sta.addr);
 499
 500         /* prepare collected frames for transmission */
 501         skb_queue_walk(&frames, skb) {
 502                 struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
 503                 struct ieee80211_hdr *hdr = (void *) skb->data;
 504
 505                 /*
 506                  * Tell TX path to send this frame even though the
 507                  * STA may still remain is PS mode after this frame
 508                  * exchange.
 509                  */
 510                 info->flags |= IEEE80211_TX_CTL_NO_PS_BUFFER;
 511
 512                 if (more_data || !skb_queue_is_last(&frames, skb))
 513                         hdr->frame_control |=
 514                                 cpu_to_le16(IEEE80211_FCTL_MOREDATA);
 515                 else
 516                         hdr->frame_control &=
 517                                 cpu_to_le16(~IEEE80211_FCTL_MOREDATA);
 518
 519                 if (skb_queue_is_last(&frames, skb) &&
 520                     ieee80211_is_data_qos(hdr->frame_control)) {
 521                         u8 *qoshdr = ieee80211_get_qos_ctl(hdr);
 522
 523                         /* MPSP trigger frame ends service period */
 524                         *qoshdr |= IEEE80211_QOS_CTL_EOSP;
 525                         info->flags |= IEEE80211_TX_CTL_REQ_TX_STATUS;
 526                 }
 527         }
 528
 529         ieee80211_add_pending_skbs(local, &frames);
 530         sta_info_recalc_tim(sta);
 531 }
 532
 533 /**
 534  * ieee80211_mpsp_trigger_process - track status of mesh Peer Service Periods
 535  *
 536  * @qc: QoS Control field
 537  * @sta: peer to start a MPSP with
 538  * @tx: frame was transmitted by the local STA
 539  * @acked: frame has been transmitted successfully
 540  *
 541  * NOTE: active mode STA may only serve as MPSP owner
 542  */
 543 void ieee80211_mpsp_trigger_process(u8 *qc, struct sta_info *sta,
 544                                     bool tx, bool acked)
 545 {
 546         u8 rspi = qc[1] & (IEEE80211_QOS_CTL_RSPI >> 8);
 547         u8 eosp = qc[0] & IEEE80211_QOS_CTL_EOSP;
 548
 549         if (tx) {
 550                 if (rspi && acked)
 551                         set_sta_flag(sta, WLAN_STA_MPSP_RECIPIENT);
 552
 553                 if (eosp)
 554                         clear_sta_flag(sta, WLAN_STA_MPSP_OWNER);
 555                 else if (acked &&
 556                          test_sta_flag(sta, WLAN_STA_PS_STA) &&
 557                          !test_and_set_sta_flag(sta, WLAN_STA_MPSP_OWNER))
 558                         mps_frame_deliver(sta, -1);
 559         } else {
 560                 if (eosp)
 561                         clear_sta_flag(sta, WLAN_STA_MPSP_RECIPIENT);
 562                 else if (sta->mesh->local_pm != NL80211_MESH_POWER_ACTIVE)
 563                         set_sta_flag(sta, WLAN_STA_MPSP_RECIPIENT);
 564
 565                 if (rspi && !test_and_set_sta_flag(sta, WLAN_STA_MPSP_OWNER))
 566                         mps_frame_deliver(sta, -1);
 567         }
 568 }
 569
 570 /**
 571  * ieee80211_mps_frame_release - release frames buffered due to mesh power save
 572  *
 573  * @sta: mesh STA
 574  * @elems: IEs of beacon or probe response
 575  *
 576  * For peers if we have individually-addressed frames buffered or the peer
 577  * indicates buffered frames, send a corresponding MPSP trigger frame. Since
 578  * we do not evaluate the awake window duration, QoS Nulls are used as MPSP
 579  * trigger frames. If the neighbour STA is not a peer, only send single frames.
 580  */
 581 void ieee80211_mps_frame_release(struct sta_info *sta,
 582                                  struct ieee802_11_elems *elems)
 583 {
 584         int ac, buffer_local = 0;
 585         bool has_buffered = false;
 586
 587         if (sta->mesh->plink_state == NL80211_PLINK_ESTAB)
 588                 has_buffered = ieee80211_check_tim(elems->tim, elems->tim_len,
 589                                                    sta->mesh->aid);
 590
 591         if (has_buffered)
 592                 mps_dbg(sta->sdata, "%pM indicates buffered frames\n",
 593                         sta->sta.addr);
 594
 595         /* only transmit to PS STA with announced, non-zero awake window */
 596         if (test_sta_flag(sta, WLAN_STA_PS_STA) &&
 597             (!elems->awake_window || !get_unaligned_le16(elems->awake_window)))
 598                 return;
 599
 600         if (!test_sta_flag(sta, WLAN_STA_MPSP_OWNER))
 601                 for (ac = 0; ac < IEEE80211_NUM_ACS; ac++)
 602                         buffer_local += skb_queue_len(&sta->ps_tx_buf[ac]) +
 603                                         skb_queue_len(&sta->tx_filtered[ac]);
 604
 605         if (!has_buffered && !buffer_local)
 606                 return;
 607
 608         if (sta->mesh->plink_state == NL80211_PLINK_ESTAB)
 609                 mpsp_trigger_send(sta, has_buffered, !buffer_local);
 610         else
 611                 mps_frame_deliver(sta, 1);
 612 }