Release 4.11 net/mac80211/mesh_sync.c

/*
 * Copyright 2011-2012, Pavel Zubarev <pavel.zubarev@gmail.com>
 * Copyright 2011-2012, Marco Porsch <marco.porsch@s2005.tu-chemnitz.de>
 * Copyright 2011-2012, cozybit Inc.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include "ieee80211_i.h"
#include "mesh.h"
#include "driver-ops.h"

/* This is not in the standard.  It represents a tolerable tsf drift below
 * which we do no TSF adjustment.
 */

#define TOFFSET_MINIMUM_ADJUSTMENT 10

/* This is not in the standard. It is a margin added to the
 * Toffset setpoint to mitigate TSF overcorrection
 * introduced by TSF adjustment latency.
 */

#define TOFFSET_SET_MARGIN 20

/* This is not in the standard.  It represents the maximum Toffset jump above
 * which we'll invalidate the Toffset setpoint and choose a new setpoint.  This
 * could be, for instance, in case a neighbor is restarted and its TSF counter
 * reset.
 */

#define TOFFSET_MAXIMUM_ADJUSTMENT 800		
/* 0.8 ms */


struct sync_method {
	
u8 method;
	
struct ieee80211_mesh_sync_ops ops;
};

/**
 * mesh_peer_tbtt_adjusting - check if an mp is currently adjusting its TBTT
 *
 * @ie: information elements of a management frame from the mesh peer
 */


static bool mesh_peer_tbtt_adjusting(struct ieee802_11_elems *ie)
{
	return (ie->mesh_config->meshconf_cap &
			IEEE80211_MESHCONF_CAPAB_TBTT_ADJUSTING) != 0;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Javier Cardona
23
95.83%
1
50.00%
Marco Porsch
1
4.17%
1
50.00%
Total
24
100.00%
2
100.00%



void mesh_sync_adjust_tsf(struct ieee80211_sub_if_data *sdata)
{
	struct ieee80211_local *local = sdata->local;
	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
	/* sdata->vif.bss_conf.beacon_int in 1024us units, 0.04% */
	u64 beacon_int_fraction = sdata->vif.bss_conf.beacon_int * 1024 / 2500;
	u64 tsf;
	u64 tsfdelta;

	spin_lock_bh(&ifmsh->sync_offset_lock);
	if (ifmsh->sync_offset_clockdrift_max < beacon_int_fraction) {
		msync_dbg(sdata, "TSF : max clockdrift=%lld; adjusting\n",
			  (long long) ifmsh->sync_offset_clockdrift_max);
		tsfdelta = -ifmsh->sync_offset_clockdrift_max;
		ifmsh->sync_offset_clockdrift_max = 0;
	} else {
		msync_dbg(sdata, "TSF : max clockdrift=%lld; adjusting by %llu\n",
			  (long long) ifmsh->sync_offset_clockdrift_max,
			  (unsigned long long) beacon_int_fraction);
		tsfdelta = -beacon_int_fraction;
		ifmsh->sync_offset_clockdrift_max -= beacon_int_fraction;
	}
	spin_unlock_bh(&ifmsh->sync_offset_lock);

	if (local->ops->offset_tsf) {
		drv_offset_tsf(local, sdata, tsfdelta);
	} else {
		tsf = drv_get_tsf(local, sdata);
		if (tsf != -1ULL)
			drv_set_tsf(local, sdata, tsf + tsfdelta);
	}
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Javier Cardona
155
80.73%
1
20.00%
Thomas Pedersen
30
15.62%
2
40.00%
Johannes Berg
4
2.08%
1
20.00%
Masashi Honma
3
1.56%
1
20.00%
Total
192
100.00%
5
100.00%



static void mesh_sync_offset_rx_bcn_presp(struct ieee80211_sub_if_data *sdata,
				   u16 stype,
				   struct ieee80211_mgmt *mgmt,
				   struct ieee802_11_elems *elems,
				   struct ieee80211_rx_status *rx_status)
{
	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
	struct ieee80211_local *local = sdata->local;
	struct sta_info *sta;
	u64 t_t, t_r;

	WARN_ON(ifmsh->mesh_sp_id != IEEE80211_SYNC_METHOD_NEIGHBOR_OFFSET);

	/* standard mentions only beacons */
	if (stype != IEEE80211_STYPE_BEACON)
		return;

	/*
         * Get time when timestamp field was received.  If we don't
         * have rx timestamps, then use current tsf as an approximation.
         * drv_get_tsf() must be called before entering the rcu-read
         * section.
         */
	if (ieee80211_have_rx_timestamp(rx_status))
		t_r = ieee80211_calculate_rx_timestamp(local, rx_status,
						       24 + 12 +
						       elems->total_len +
						       FCS_LEN,
						       24);
	else
		t_r = drv_get_tsf(local, sdata);

	rcu_read_lock();
	sta = sta_info_get(sdata, mgmt->sa);
	if (!sta)
		goto no_sync;

	/* check offset sync conditions (13.13.2.2.1)
         *
         * TODO also sync to
         * dot11MeshNbrOffsetMaxNeighbor non-peer non-MBSS neighbors
         */

	if (elems->mesh_config && mesh_peer_tbtt_adjusting(elems)) {
		msync_dbg(sdata, "STA %pM : is adjusting TBTT\n",
			  sta->sta.addr);
		goto no_sync;
	}

	/* Timing offset calculation (see 13.13.2.2.2) */
	t_t = le64_to_cpu(mgmt->u.beacon.timestamp);
	sta->mesh->t_offset = t_t - t_r;

	if (test_sta_flag(sta, WLAN_STA_TOFFSET_KNOWN)) {
		s64 t_clockdrift = sta->mesh->t_offset_setpoint - sta->mesh->t_offset;
		msync_dbg(sdata,
			  "STA %pM : t_offset=%lld, t_offset_setpoint=%lld, t_clockdrift=%lld\n",
			  sta->sta.addr, (long long) sta->mesh->t_offset,
			  (long long) sta->mesh->t_offset_setpoint,
			  (long long) t_clockdrift);

		if (t_clockdrift > TOFFSET_MAXIMUM_ADJUSTMENT ||
		    t_clockdrift < -TOFFSET_MAXIMUM_ADJUSTMENT) {
			msync_dbg(sdata,
				  "STA %pM : t_clockdrift=%lld too large, setpoint reset\n",
				  sta->sta.addr,
				  (long long) t_clockdrift);
			clear_sta_flag(sta, WLAN_STA_TOFFSET_KNOWN);
			goto no_sync;
		}

		spin_lock_bh(&ifmsh->sync_offset_lock);
		if (t_clockdrift > ifmsh->sync_offset_clockdrift_max)
			ifmsh->sync_offset_clockdrift_max = t_clockdrift;
		spin_unlock_bh(&ifmsh->sync_offset_lock);
	} else {
		sta->mesh->t_offset_setpoint = sta->mesh->t_offset - TOFFSET_SET_MARGIN;
		set_sta_flag(sta, WLAN_STA_TOFFSET_KNOWN);
		msync_dbg(sdata,
			  "STA %pM : offset was invalid, t_offset=%lld\n",
			  sta->sta.addr,
			  (long long) sta->mesh->t_offset);
	}

no_sync:
	rcu_read_unlock();
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Javier Cardona
323
84.78%
3
50.00%
Bob Copeland
30
7.87%
1
16.67%
Johannes Berg
28
7.35%
2
33.33%
Total
381
100.00%
6
100.00%



static void mesh_sync_offset_adjust_tsf(struct ieee80211_sub_if_data *sdata,
					 struct beacon_data *beacon)
{
	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;

	WARN_ON(ifmsh->mesh_sp_id != IEEE80211_SYNC_METHOD_NEIGHBOR_OFFSET);
	WARN_ON(!rcu_read_lock_held());

	spin_lock_bh(&ifmsh->sync_offset_lock);

	if (ifmsh->sync_offset_clockdrift_max > TOFFSET_MINIMUM_ADJUSTMENT) {
		/* Since ajusting the tsf here would
                 * require a possibly blocking call
                 * to the driver tsf setter, we punt
                 * the tsf adjustment to the mesh tasklet
                 */
		msync_dbg(sdata,
			  "TSF : kicking off TSF adjustment with clockdrift_max=%lld\n",
			  ifmsh->sync_offset_clockdrift_max);
		set_bit(MESH_WORK_DRIFT_ADJUST, &ifmsh->wrkq_flags);
	} else {
		msync_dbg(sdata,
			  "TSF : max clockdrift=%lld; too small to adjust\n",
			  (long long)ifmsh->sync_offset_clockdrift_max);
		ifmsh->sync_offset_clockdrift_max = 0;
	}
	spin_unlock_bh(&ifmsh->sync_offset_lock);
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Javier Cardona
103
88.79%
2
33.33%
Johannes Berg
5
4.31%
2
33.33%
Thomas Pedersen
5
4.31%
1
16.67%
Masashi Honma
3
2.59%
1
16.67%
Total
116
100.00%
6
100.00%


static const struct sync_method sync_methods[] = {
	{
		.method = IEEE80211_SYNC_METHOD_NEIGHBOR_OFFSET,
		.ops = {
			.rx_bcn_presp = &mesh_sync_offset_rx_bcn_presp,
			.adjust_tsf = &mesh_sync_offset_adjust_tsf,
                }
	},
};



const struct ieee80211_mesh_sync_ops *ieee80211_mesh_sync_ops_get(u8 method)
{
	int i;

	for (i = 0 ; i < ARRAY_SIZE(sync_methods); ++i) {
		if (sync_methods[i].method == method)
			return &sync_methods[i].ops;
	}
	return NULL;
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
Javier Cardona
50
90.91%
1
33.33%
Johannes Berg
5
9.09%
2
66.67%
Total
55
100.00%
3
100.00%

Overall Contributors
Person
Tokens
Prop
Commits
CommitProp
Javier Cardona
720
85.71%
4
25.00%
Johannes Berg
43
5.12%
5
31.25%
Thomas Pedersen
37
4.40%
4
25.00%
Bob Copeland
30
3.57%
1
6.25%
Masashi Honma
9
1.07%
1
6.25%
Marco Porsch
1
0.12%
1
6.25%
Total
840
100.00%
16
100.00%
Directory: net/mac80211

Information contained on this website is for historical information purposes only and does not indicate or represent copyright ownership.