1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
|
/*
* 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 tbtt 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 30000 /* 30 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 &
MESHCONF_CAPAB_TBTT_ADJUSTING) != 0;
}
void mesh_sync_adjust_tbtt(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, "TBTT : 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, "TBTT : 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);
tsf = drv_get_tsf(local, sdata);
if (tsf != -1ULL)
drv_set_tsf(local, sdata, tsf + tsfdelta);
}
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;
/* The current tsf is a first approximation for the timestamp
* for the received beacon. Further down we try to get a
* better value from the rx_status->mactime field if
* available. Also we have to call drv_get_tsf() before
* entering the rcu-read section.*/
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)) {
clear_sta_flag(sta, WLAN_STA_TOFFSET_KNOWN);
msync_dbg(sdata, "STA %pM : is adjusting TBTT\n", sta->sta.addr);
goto no_sync;
}
if (ieee80211_have_rx_timestamp(rx_status))
/* time when timestamp field was received */
t_r = ieee80211_calculate_rx_timestamp(local, rx_status,
24 + 12 +
elems->total_len +
FCS_LEN,
24);
/* Timing offset calculation (see 13.13.2.2.2) */
t_t = le64_to_cpu(mgmt->u.beacon.timestamp);
sta->t_offset = t_t - t_r;
if (test_sta_flag(sta, WLAN_STA_TOFFSET_KNOWN)) {
s64 t_clockdrift = sta->t_offset_setpoint
- sta->t_offset;
msync_dbg(sdata,
"STA %pM : sta->t_offset=%lld, sta->t_offset_setpoint=%lld, t_clockdrift=%lld\n",
sta->sta.addr,
(long long) sta->t_offset,
(long long)
sta->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;
}
rcu_read_unlock();
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->t_offset_setpoint = sta->t_offset - TOFFSET_SET_MARGIN;
set_sta_flag(sta, WLAN_STA_TOFFSET_KNOWN);
msync_dbg(sdata,
"STA %pM : offset was invalid, sta->t_offset=%lld\n",
sta->sta.addr,
(long long) sta->t_offset);
rcu_read_unlock();
}
return;
no_sync:
rcu_read_unlock();
}
static void mesh_sync_offset_adjust_tbtt(struct ieee80211_sub_if_data *sdata)
{
struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
WARN_ON(ifmsh->mesh_sp_id
!= IEEE80211_SYNC_METHOD_NEIGHBOR_OFFSET);
BUG_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,
"TBTT : kicking off TBTT adjustment with clockdrift_max=%lld\n",
ifmsh->sync_offset_clockdrift_max);
set_bit(MESH_WORK_DRIFT_ADJUST,
&ifmsh->wrkq_flags);
} else {
msync_dbg(sdata,
"TBTT : 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);
}
static const struct sync_method sync_methods[] = {
{
.method = IEEE80211_SYNC_METHOD_NEIGHBOR_OFFSET,
.ops = {
.rx_bcn_presp = &mesh_sync_offset_rx_bcn_presp,
.adjust_tbtt = &mesh_sync_offset_adjust_tbtt,
}
},
};
const struct ieee80211_mesh_sync_ops *ieee80211_mesh_sync_ops_get(u8 method)
{
const struct ieee80211_mesh_sync_ops *ops = NULL;
u8 i;
for (i = 0 ; i < ARRAY_SIZE(sync_methods); ++i) {
if (sync_methods[i].method == method) {
ops = &sync_methods[i].ops;
break;
}
}
return ops;
}
|
