372039031c
Currently the mesh sync code checks, whether peers indicate TBTT adjustment, but it never sets the corresponding flag itself. By setting ifmsh->tbtt_adjusting to true, it will set the corresponding field in the mesh configuration IE of own beacons. This indication will be set in the current beacon. The TBTT adjustment will be performed afterwards, affecting the next beacon. Thus, the first beacon with stable TBTT will not indicate adjustment anymore and peers will continue tracking the new offset. Signed-off-by: Marco Porsch <marco.porsch@etit.tu-chemnitz.de> Signed-off-by: Johannes Berg <johannes.berg@intel.com>
234 lines
6.7 KiB
C
234 lines
6.7 KiB
C
/*
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* Copyright 2011-2012, Pavel Zubarev <pavel.zubarev@gmail.com>
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* Copyright 2011-2012, Marco Porsch <marco.porsch@s2005.tu-chemnitz.de>
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* Copyright 2011-2012, cozybit Inc.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include "ieee80211_i.h"
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#include "mesh.h"
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#include "driver-ops.h"
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/* This is not in the standard. It represents a tolerable tbtt drift below
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* which we do no TSF adjustment.
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*/
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#define TOFFSET_MINIMUM_ADJUSTMENT 10
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/* This is not in the standard. It is a margin added to the
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* Toffset setpoint to mitigate TSF overcorrection
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* introduced by TSF adjustment latency.
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*/
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#define TOFFSET_SET_MARGIN 20
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/* This is not in the standard. It represents the maximum Toffset jump above
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* which we'll invalidate the Toffset setpoint and choose a new setpoint. This
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* could be, for instance, in case a neighbor is restarted and its TSF counter
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* reset.
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*/
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#define TOFFSET_MAXIMUM_ADJUSTMENT 30000 /* 30 ms */
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struct sync_method {
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u8 method;
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struct ieee80211_mesh_sync_ops ops;
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};
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/**
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* mesh_peer_tbtt_adjusting - check if an mp is currently adjusting its TBTT
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*
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* @ie: information elements of a management frame from the mesh peer
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*/
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static bool mesh_peer_tbtt_adjusting(struct ieee802_11_elems *ie)
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{
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return (ie->mesh_config->meshconf_cap &
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IEEE80211_MESHCONF_CAPAB_TBTT_ADJUSTING) != 0;
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}
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void mesh_sync_adjust_tbtt(struct ieee80211_sub_if_data *sdata)
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{
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struct ieee80211_local *local = sdata->local;
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struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
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/* sdata->vif.bss_conf.beacon_int in 1024us units, 0.04% */
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u64 beacon_int_fraction = sdata->vif.bss_conf.beacon_int * 1024 / 2500;
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u64 tsf;
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u64 tsfdelta;
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spin_lock_bh(&ifmsh->sync_offset_lock);
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if (ifmsh->sync_offset_clockdrift_max < beacon_int_fraction) {
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msync_dbg(sdata, "TBTT : max clockdrift=%lld; adjusting\n",
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(long long) ifmsh->sync_offset_clockdrift_max);
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tsfdelta = -ifmsh->sync_offset_clockdrift_max;
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ifmsh->sync_offset_clockdrift_max = 0;
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} else {
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msync_dbg(sdata, "TBTT : max clockdrift=%lld; adjusting by %llu\n",
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(long long) ifmsh->sync_offset_clockdrift_max,
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(unsigned long long) beacon_int_fraction);
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tsfdelta = -beacon_int_fraction;
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ifmsh->sync_offset_clockdrift_max -= beacon_int_fraction;
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}
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spin_unlock_bh(&ifmsh->sync_offset_lock);
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tsf = drv_get_tsf(local, sdata);
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if (tsf != -1ULL)
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drv_set_tsf(local, sdata, tsf + tsfdelta);
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}
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static void mesh_sync_offset_rx_bcn_presp(struct ieee80211_sub_if_data *sdata,
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u16 stype,
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struct ieee80211_mgmt *mgmt,
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struct ieee802_11_elems *elems,
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struct ieee80211_rx_status *rx_status)
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{
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struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
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struct ieee80211_local *local = sdata->local;
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struct sta_info *sta;
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u64 t_t, t_r;
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WARN_ON(ifmsh->mesh_sp_id != IEEE80211_SYNC_METHOD_NEIGHBOR_OFFSET);
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/* standard mentions only beacons */
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if (stype != IEEE80211_STYPE_BEACON)
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return;
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/* The current tsf is a first approximation for the timestamp
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* for the received beacon. Further down we try to get a
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* better value from the rx_status->mactime field if
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* available. Also we have to call drv_get_tsf() before
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* entering the rcu-read section.*/
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t_r = drv_get_tsf(local, sdata);
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rcu_read_lock();
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sta = sta_info_get(sdata, mgmt->sa);
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if (!sta)
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goto no_sync;
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/* check offset sync conditions (13.13.2.2.1)
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*
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* TODO also sync to
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* dot11MeshNbrOffsetMaxNeighbor non-peer non-MBSS neighbors
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*/
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if (elems->mesh_config && mesh_peer_tbtt_adjusting(elems)) {
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clear_sta_flag(sta, WLAN_STA_TOFFSET_KNOWN);
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msync_dbg(sdata, "STA %pM : is adjusting TBTT\n", sta->sta.addr);
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goto no_sync;
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}
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if (ieee80211_have_rx_timestamp(rx_status))
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/* time when timestamp field was received */
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t_r = ieee80211_calculate_rx_timestamp(local, rx_status,
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24 + 12 +
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elems->total_len +
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FCS_LEN,
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24);
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/* Timing offset calculation (see 13.13.2.2.2) */
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t_t = le64_to_cpu(mgmt->u.beacon.timestamp);
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sta->t_offset = t_t - t_r;
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if (test_sta_flag(sta, WLAN_STA_TOFFSET_KNOWN)) {
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s64 t_clockdrift = sta->t_offset_setpoint
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- sta->t_offset;
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msync_dbg(sdata,
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"STA %pM : sta->t_offset=%lld, sta->t_offset_setpoint=%lld, t_clockdrift=%lld\n",
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sta->sta.addr,
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(long long) sta->t_offset,
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(long long)
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sta->t_offset_setpoint,
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(long long) t_clockdrift);
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if (t_clockdrift > TOFFSET_MAXIMUM_ADJUSTMENT ||
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t_clockdrift < -TOFFSET_MAXIMUM_ADJUSTMENT) {
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msync_dbg(sdata,
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"STA %pM : t_clockdrift=%lld too large, setpoint reset\n",
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sta->sta.addr,
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(long long) t_clockdrift);
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clear_sta_flag(sta, WLAN_STA_TOFFSET_KNOWN);
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goto no_sync;
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}
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rcu_read_unlock();
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spin_lock_bh(&ifmsh->sync_offset_lock);
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if (t_clockdrift >
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ifmsh->sync_offset_clockdrift_max)
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ifmsh->sync_offset_clockdrift_max
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= t_clockdrift;
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spin_unlock_bh(&ifmsh->sync_offset_lock);
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} else {
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sta->t_offset_setpoint = sta->t_offset - TOFFSET_SET_MARGIN;
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set_sta_flag(sta, WLAN_STA_TOFFSET_KNOWN);
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msync_dbg(sdata,
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"STA %pM : offset was invalid, sta->t_offset=%lld\n",
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sta->sta.addr,
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(long long) sta->t_offset);
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rcu_read_unlock();
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}
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return;
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no_sync:
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rcu_read_unlock();
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}
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static void mesh_sync_offset_adjust_tbtt(struct ieee80211_sub_if_data *sdata)
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{
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struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
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WARN_ON(ifmsh->mesh_sp_id
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!= IEEE80211_SYNC_METHOD_NEIGHBOR_OFFSET);
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BUG_ON(!rcu_read_lock_held());
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spin_lock_bh(&ifmsh->sync_offset_lock);
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if (ifmsh->sync_offset_clockdrift_max >
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TOFFSET_MINIMUM_ADJUSTMENT) {
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/* Since ajusting the tsf here would
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* require a possibly blocking call
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* to the driver tsf setter, we punt
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* the tsf adjustment to the mesh tasklet
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*/
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msync_dbg(sdata,
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"TBTT : kicking off TBTT adjustment with clockdrift_max=%lld\n",
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ifmsh->sync_offset_clockdrift_max);
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set_bit(MESH_WORK_DRIFT_ADJUST,
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&ifmsh->wrkq_flags);
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ifmsh->adjusting_tbtt = true;
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} else {
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msync_dbg(sdata,
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"TBTT : max clockdrift=%lld; too small to adjust\n",
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(long long)ifmsh->sync_offset_clockdrift_max);
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ifmsh->sync_offset_clockdrift_max = 0;
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ifmsh->adjusting_tbtt = false;
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}
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spin_unlock_bh(&ifmsh->sync_offset_lock);
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}
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static const struct sync_method sync_methods[] = {
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{
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.method = IEEE80211_SYNC_METHOD_NEIGHBOR_OFFSET,
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.ops = {
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.rx_bcn_presp = &mesh_sync_offset_rx_bcn_presp,
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.adjust_tbtt = &mesh_sync_offset_adjust_tbtt,
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}
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},
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};
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const struct ieee80211_mesh_sync_ops *ieee80211_mesh_sync_ops_get(u8 method)
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{
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const struct ieee80211_mesh_sync_ops *ops = NULL;
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u8 i;
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for (i = 0 ; i < ARRAY_SIZE(sync_methods); ++i) {
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if (sync_methods[i].method == method) {
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ops = &sync_methods[i].ops;
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break;
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}
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}
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return ops;
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}
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