blob: 5abddfe3e1014f7bf19b4efaf5d19d6d20303467 [file] [log] [blame]
Jouni Malinenb203ffc2009-12-23 13:15:40 +01001/*
2 * Off-channel operation helpers
3 *
4 * Copyright 2003, Jouni Malinen <jkmaline@cc.hut.fi>
5 * Copyright 2004, Instant802 Networks, Inc.
6 * Copyright 2005, Devicescape Software, Inc.
7 * Copyright 2006-2007 Jiri Benc <jbenc@suse.cz>
8 * Copyright 2007, Michael Wu <flamingice@sourmilk.net>
9 * Copyright 2009 Johannes Berg <johannes@sipsolutions.net>
10 *
11 * This program is free software; you can redistribute it and/or modify
12 * it under the terms of the GNU General Public License version 2 as
13 * published by the Free Software Foundation.
14 */
Paul Gortmakerbc3b2d72011-07-15 11:47:34 -040015#include <linux/export.h>
Jouni Malinenb203ffc2009-12-23 13:15:40 +010016#include <net/mac80211.h>
17#include "ieee80211_i.h"
Johannes Berg2eb278e2012-06-05 14:28:42 +020018#include "driver-ops.h"
Jouni Malinenb203ffc2009-12-23 13:15:40 +010019
20/*
Ben Greearb23b0252011-02-04 11:54:17 -080021 * Tell our hardware to disable PS.
22 * Optionally inform AP that we will go to sleep so that it will buffer
23 * the frames while we are doing off-channel work. This is optional
24 * because we *may* be doing work on-operating channel, and want our
25 * hardware unconditionally awake, but still let the AP send us normal frames.
Jouni Malinenb203ffc2009-12-23 13:15:40 +010026 */
Rajkumar Manoharan559cef92012-06-18 19:03:52 +053027static void ieee80211_offchannel_ps_enable(struct ieee80211_sub_if_data *sdata)
Jouni Malinenb203ffc2009-12-23 13:15:40 +010028{
29 struct ieee80211_local *local = sdata->local;
Luis R. Rodriguez4730d592010-09-16 15:12:31 -040030 struct ieee80211_if_managed *ifmgd = &sdata->u.mgd;
Jouni Malinenb203ffc2009-12-23 13:15:40 +010031
32 local->offchannel_ps_enabled = false;
33
34 /* FIXME: what to do when local->pspolling is true? */
35
36 del_timer_sync(&local->dynamic_ps_timer);
Luis R. Rodriguez3bc3c0d2010-09-16 15:12:33 -040037 del_timer_sync(&ifmgd->bcn_mon_timer);
Luis R. Rodriguez4730d592010-09-16 15:12:31 -040038 del_timer_sync(&ifmgd->conn_mon_timer);
39
Jouni Malinenb203ffc2009-12-23 13:15:40 +010040 cancel_work_sync(&local->dynamic_ps_enable_work);
41
42 if (local->hw.conf.flags & IEEE80211_CONF_PS) {
43 local->offchannel_ps_enabled = true;
44 local->hw.conf.flags &= ~IEEE80211_CONF_PS;
45 ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_PS);
46 }
47
Rajkumar Manoharan559cef92012-06-18 19:03:52 +053048 if (!local->offchannel_ps_enabled ||
49 !(local->hw.flags & IEEE80211_HW_PS_NULLFUNC_STACK))
Jouni Malinenb203ffc2009-12-23 13:15:40 +010050 /*
51 * If power save was enabled, no need to send a nullfunc
52 * frame because AP knows that we are sleeping. But if the
53 * hardware is creating the nullfunc frame for power save
54 * status (ie. IEEE80211_HW_PS_NULLFUNC_STACK is not
55 * enabled) and power save was enabled, the firmware just
56 * sent a null frame with power save disabled. So we need
57 * to send a new nullfunc frame to inform the AP that we
58 * are again sleeping.
59 */
60 ieee80211_send_nullfunc(local, sdata, 1);
61}
62
63/* inform AP that we are awake again, unless power save is enabled */
64static void ieee80211_offchannel_ps_disable(struct ieee80211_sub_if_data *sdata)
65{
66 struct ieee80211_local *local = sdata->local;
67
68 if (!local->ps_sdata)
69 ieee80211_send_nullfunc(local, sdata, 0);
70 else if (local->offchannel_ps_enabled) {
71 /*
72 * In !IEEE80211_HW_PS_NULLFUNC_STACK case the hardware
73 * will send a nullfunc frame with the powersave bit set
74 * even though the AP already knows that we are sleeping.
75 * This could be avoided by sending a null frame with power
76 * save bit disabled before enabling the power save, but
77 * this doesn't gain anything.
78 *
79 * When IEEE80211_HW_PS_NULLFUNC_STACK is enabled, no need
80 * to send a nullfunc frame because AP already knows that
81 * we are sleeping, let's just enable power save mode in
82 * hardware.
83 */
Ben Greearb23b0252011-02-04 11:54:17 -080084 /* TODO: Only set hardware if CONF_PS changed?
85 * TODO: Should we set offchannel_ps_enabled to false?
86 */
Jouni Malinenb203ffc2009-12-23 13:15:40 +010087 local->hw.conf.flags |= IEEE80211_CONF_PS;
88 ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_PS);
89 } else if (local->hw.conf.dynamic_ps_timeout > 0) {
90 /*
91 * If IEEE80211_CONF_PS was not set and the dynamic_ps_timer
92 * had been running before leaving the operating channel,
93 * restart the timer now and send a nullfunc frame to inform
94 * the AP that we are awake.
95 */
96 ieee80211_send_nullfunc(local, sdata, 0);
97 mod_timer(&local->dynamic_ps_timer, jiffies +
98 msecs_to_jiffies(local->hw.conf.dynamic_ps_timeout));
99 }
Luis R. Rodriguez4730d592010-09-16 15:12:31 -0400100
Luis R. Rodriguez3bc3c0d2010-09-16 15:12:33 -0400101 ieee80211_sta_reset_beacon_monitor(sdata);
Luis R. Rodriguez4730d592010-09-16 15:12:31 -0400102 ieee80211_sta_reset_conn_monitor(sdata);
Jouni Malinenb203ffc2009-12-23 13:15:40 +0100103}
104
Ben Greearb23b0252011-02-04 11:54:17 -0800105void ieee80211_offchannel_stop_vifs(struct ieee80211_local *local,
106 bool offchannel_ps_enable)
Jouni Malinenb203ffc2009-12-23 13:15:40 +0100107{
108 struct ieee80211_sub_if_data *sdata;
109
Johannes Bergfe57d9f2012-07-26 14:55:08 +0200110 if (WARN_ON(local->use_chanctx))
111 return;
112
Jouni Malinenb203ffc2009-12-23 13:15:40 +0100113 /*
Ben Greearb23b0252011-02-04 11:54:17 -0800114 * notify the AP about us leaving the channel and stop all
115 * STA interfaces.
Jouni Malinenb203ffc2009-12-23 13:15:40 +0100116 */
117 mutex_lock(&local->iflist_mtx);
118 list_for_each_entry(sdata, &local->interfaces, list) {
119 if (!ieee80211_sdata_running(sdata))
120 continue;
121
Johannes Bergf142c6b2012-06-18 20:07:15 +0200122 if (sdata->vif.type == NL80211_IFTYPE_P2P_DEVICE)
123 continue;
124
Ben Greearb23b0252011-02-04 11:54:17 -0800125 if (sdata->vif.type != NL80211_IFTYPE_MONITOR)
Johannes Berg5b714c62010-08-27 13:45:28 +0200126 set_bit(SDATA_STATE_OFFCHANNEL, &sdata->state);
Ben Greearb23b0252011-02-04 11:54:17 -0800127
128 /* Check to see if we should disable beaconing. */
129 if (sdata->vif.type == NL80211_IFTYPE_AP ||
130 sdata->vif.type == NL80211_IFTYPE_ADHOC ||
131 sdata->vif.type == NL80211_IFTYPE_MESH_POINT)
132 ieee80211_bss_info_change_notify(
133 sdata, BSS_CHANGED_BEACON_ENABLED);
134
135 if (sdata->vif.type != NL80211_IFTYPE_MONITOR) {
John W. Linvillecfa6cb22010-01-06 17:22:54 -0500136 netif_tx_stop_all_queues(sdata->dev);
Ben Greearb23b0252011-02-04 11:54:17 -0800137 if (offchannel_ps_enable &&
138 (sdata->vif.type == NL80211_IFTYPE_STATION) &&
139 sdata->u.mgd.associated)
Rajkumar Manoharan559cef92012-06-18 19:03:52 +0530140 ieee80211_offchannel_ps_enable(sdata);
Jouni Malinenb203ffc2009-12-23 13:15:40 +0100141 }
142 }
143 mutex_unlock(&local->iflist_mtx);
144}
145
146void ieee80211_offchannel_return(struct ieee80211_local *local,
Ben Greearb23b0252011-02-04 11:54:17 -0800147 bool offchannel_ps_disable)
Jouni Malinenb203ffc2009-12-23 13:15:40 +0100148{
149 struct ieee80211_sub_if_data *sdata;
150
Johannes Bergfe57d9f2012-07-26 14:55:08 +0200151 if (WARN_ON(local->use_chanctx))
152 return;
153
Jouni Malinenb203ffc2009-12-23 13:15:40 +0100154 mutex_lock(&local->iflist_mtx);
155 list_for_each_entry(sdata, &local->interfaces, list) {
Johannes Bergf142c6b2012-06-18 20:07:15 +0200156 if (sdata->vif.type == NL80211_IFTYPE_P2P_DEVICE)
157 continue;
158
Eliad Pellerf6e8cb72011-12-23 01:48:06 +0200159 if (sdata->vif.type != NL80211_IFTYPE_MONITOR)
160 clear_bit(SDATA_STATE_OFFCHANNEL, &sdata->state);
161
Jouni Malinenb203ffc2009-12-23 13:15:40 +0100162 if (!ieee80211_sdata_running(sdata))
163 continue;
164
165 /* Tell AP we're back */
Ben Greearb23b0252011-02-04 11:54:17 -0800166 if (offchannel_ps_disable &&
167 sdata->vif.type == NL80211_IFTYPE_STATION) {
Jouni Malinenb203ffc2009-12-23 13:15:40 +0100168 if (sdata->u.mgd.associated)
169 ieee80211_offchannel_ps_disable(sdata);
Jouni Malinenb203ffc2009-12-23 13:15:40 +0100170 }
171
Johannes Berg5b714c62010-08-27 13:45:28 +0200172 if (sdata->vif.type != NL80211_IFTYPE_MONITOR) {
Johannes Berg5b714c62010-08-27 13:45:28 +0200173 /*
174 * This may wake up queues even though the driver
175 * currently has them stopped. This is not very
176 * likely, since the driver won't have gotten any
177 * (or hardly any) new packets while we weren't
178 * on the right channel, and even if it happens
179 * it will at most lead to queueing up one more
180 * packet per queue in mac80211 rather than on
181 * the interface qdisc.
182 */
Benoit Papillault93895752010-01-14 23:20:31 +0100183 netif_tx_wake_all_queues(sdata->dev);
Johannes Berg5b714c62010-08-27 13:45:28 +0200184 }
Benoit Papillault93895752010-01-14 23:20:31 +0100185
Johannes Berge76aadc2011-11-29 10:20:02 +0100186 if (sdata->vif.type == NL80211_IFTYPE_AP ||
187 sdata->vif.type == NL80211_IFTYPE_ADHOC ||
188 sdata->vif.type == NL80211_IFTYPE_MESH_POINT)
Jouni Malinenb203ffc2009-12-23 13:15:40 +0100189 ieee80211_bss_info_change_notify(
190 sdata, BSS_CHANGED_BEACON_ENABLED);
191 }
192 mutex_unlock(&local->iflist_mtx);
193}
Johannes Berg21f83582010-12-18 17:20:47 +0100194
Johannes Berg2eb278e2012-06-05 14:28:42 +0200195void ieee80211_handle_roc_started(struct ieee80211_roc_work *roc)
196{
197 if (roc->notified)
198 return;
199
200 if (roc->mgmt_tx_cookie) {
201 if (!WARN_ON(!roc->frame)) {
Johannes Berg55de9082012-07-26 17:24:39 +0200202 ieee80211_tx_skb_tid_band(roc->sdata, roc->frame, 7,
203 roc->chan->band);
Johannes Berg2eb278e2012-06-05 14:28:42 +0200204 roc->frame = NULL;
205 }
206 } else {
Johannes Berg50febf62012-10-26 16:13:06 +0200207 cfg80211_ready_on_channel(&roc->sdata->wdev, roc->cookie,
Johannes Berg42d97a52012-11-08 18:31:02 +0100208 roc->chan, roc->req_duration,
209 GFP_KERNEL);
Johannes Berg2eb278e2012-06-05 14:28:42 +0200210 }
211
212 roc->notified = true;
213}
214
Johannes Berg21f83582010-12-18 17:20:47 +0100215static void ieee80211_hw_roc_start(struct work_struct *work)
216{
217 struct ieee80211_local *local =
218 container_of(work, struct ieee80211_local, hw_roc_start);
Johannes Berg2eb278e2012-06-05 14:28:42 +0200219 struct ieee80211_roc_work *roc, *dep, *tmp;
Johannes Berg21f83582010-12-18 17:20:47 +0100220
221 mutex_lock(&local->mtx);
222
Johannes Berg2eb278e2012-06-05 14:28:42 +0200223 if (list_empty(&local->roc_list))
224 goto out_unlock;
Johannes Berg21f83582010-12-18 17:20:47 +0100225
Johannes Berg2eb278e2012-06-05 14:28:42 +0200226 roc = list_first_entry(&local->roc_list, struct ieee80211_roc_work,
227 list);
Johannes Berg90fc4b32010-12-18 17:20:48 +0100228
Johannes Berg2eb278e2012-06-05 14:28:42 +0200229 if (!roc->started)
230 goto out_unlock;
231
232 roc->hw_begun = true;
233 roc->hw_start_time = local->hw_roc_start_time;
234
235 ieee80211_handle_roc_started(roc);
236 list_for_each_entry_safe(dep, tmp, &roc->dependents, list) {
237 ieee80211_handle_roc_started(dep);
238
239 if (dep->duration > roc->duration) {
240 u32 dur = dep->duration;
241 dep->duration = dur - roc->duration;
242 roc->duration = dur;
Wei Yongjuna4ed5342012-09-06 13:20:53 +0800243 list_move(&dep->list, &roc->list);
Johannes Berg2eb278e2012-06-05 14:28:42 +0200244 }
245 }
246 out_unlock:
Johannes Berg21f83582010-12-18 17:20:47 +0100247 mutex_unlock(&local->mtx);
248}
249
250void ieee80211_ready_on_channel(struct ieee80211_hw *hw)
251{
252 struct ieee80211_local *local = hw_to_local(hw);
253
Johannes Berg2eb278e2012-06-05 14:28:42 +0200254 local->hw_roc_start_time = jiffies;
255
Johannes Berg21f83582010-12-18 17:20:47 +0100256 trace_api_ready_on_channel(local);
257
258 ieee80211_queue_work(hw, &local->hw_roc_start);
259}
260EXPORT_SYMBOL_GPL(ieee80211_ready_on_channel);
261
Johannes Berg2eb278e2012-06-05 14:28:42 +0200262void ieee80211_start_next_roc(struct ieee80211_local *local)
263{
264 struct ieee80211_roc_work *roc;
265
266 lockdep_assert_held(&local->mtx);
267
268 if (list_empty(&local->roc_list)) {
269 ieee80211_run_deferred_scan(local);
270 return;
271 }
272
273 roc = list_first_entry(&local->roc_list, struct ieee80211_roc_work,
274 list);
275
Johannes Berg0f6b3f52012-06-20 20:11:33 +0200276 if (WARN_ON_ONCE(roc->started))
277 return;
278
Johannes Berg2eb278e2012-06-05 14:28:42 +0200279 if (local->ops->remain_on_channel) {
280 int ret, duration = roc->duration;
281
282 /* XXX: duplicated, see ieee80211_start_roc_work() */
283 if (!duration)
284 duration = 10;
285
Eliad Peller49884562012-11-19 17:05:09 +0200286 ret = drv_remain_on_channel(local, roc->sdata, roc->chan,
Johannes Berg2eb278e2012-06-05 14:28:42 +0200287 duration);
288
289 roc->started = true;
290
291 if (ret) {
292 wiphy_warn(local->hw.wiphy,
293 "failed to start next HW ROC (%d)\n", ret);
294 /*
295 * queue the work struct again to avoid recursion
296 * when multiple failures occur
297 */
298 ieee80211_remain_on_channel_expired(&local->hw);
299 }
300 } else {
301 /* delay it a bit */
302 ieee80211_queue_delayed_work(&local->hw, &roc->work,
303 round_jiffies_relative(HZ/2));
304 }
305}
306
307void ieee80211_roc_notify_destroy(struct ieee80211_roc_work *roc)
308{
309 struct ieee80211_roc_work *dep, *tmp;
310
311 /* was never transmitted */
312 if (roc->frame) {
Johannes Berg71bbc992012-06-15 15:30:18 +0200313 cfg80211_mgmt_tx_status(&roc->sdata->wdev,
Johannes Berg2eb278e2012-06-05 14:28:42 +0200314 (unsigned long)roc->frame,
315 roc->frame->data, roc->frame->len,
316 false, GFP_KERNEL);
317 kfree_skb(roc->frame);
318 }
319
320 if (!roc->mgmt_tx_cookie)
Johannes Berg71bbc992012-06-15 15:30:18 +0200321 cfg80211_remain_on_channel_expired(&roc->sdata->wdev,
Johannes Berg50febf62012-10-26 16:13:06 +0200322 roc->cookie, roc->chan,
Johannes Berg42d97a52012-11-08 18:31:02 +0100323 GFP_KERNEL);
Johannes Berg2eb278e2012-06-05 14:28:42 +0200324
325 list_for_each_entry_safe(dep, tmp, &roc->dependents, list)
326 ieee80211_roc_notify_destroy(dep);
327
328 kfree(roc);
329}
330
331void ieee80211_sw_roc_work(struct work_struct *work)
332{
333 struct ieee80211_roc_work *roc =
334 container_of(work, struct ieee80211_roc_work, work.work);
335 struct ieee80211_sub_if_data *sdata = roc->sdata;
336 struct ieee80211_local *local = sdata->local;
Alan Cox4b4b8222012-07-13 16:14:45 +0200337 bool started;
Johannes Berg2eb278e2012-06-05 14:28:42 +0200338
339 mutex_lock(&local->mtx);
340
341 if (roc->abort)
342 goto finish;
343
344 if (WARN_ON(list_empty(&local->roc_list)))
345 goto out_unlock;
346
347 if (WARN_ON(roc != list_first_entry(&local->roc_list,
348 struct ieee80211_roc_work,
349 list)))
350 goto out_unlock;
351
352 if (!roc->started) {
353 struct ieee80211_roc_work *dep;
354
355 /* start this ROC */
356
357 /* switch channel etc */
358 ieee80211_recalc_idle(local);
359
360 local->tmp_channel = roc->chan;
Johannes Berg2eb278e2012-06-05 14:28:42 +0200361 ieee80211_hw_config(local, 0);
362
363 /* tell userspace or send frame */
364 ieee80211_handle_roc_started(roc);
365 list_for_each_entry(dep, &roc->dependents, list)
366 ieee80211_handle_roc_started(dep);
367
368 /* if it was pure TX, just finish right away */
369 if (!roc->duration)
370 goto finish;
371
372 roc->started = true;
373 ieee80211_queue_delayed_work(&local->hw, &roc->work,
374 msecs_to_jiffies(roc->duration));
375 } else {
376 /* finish this ROC */
377 finish:
378 list_del(&roc->list);
Alan Cox4b4b8222012-07-13 16:14:45 +0200379 started = roc->started;
Johannes Berg2eb278e2012-06-05 14:28:42 +0200380 ieee80211_roc_notify_destroy(roc);
381
Alan Cox4b4b8222012-07-13 16:14:45 +0200382 if (started) {
Johannes Berg2eb278e2012-06-05 14:28:42 +0200383 drv_flush(local, false);
384
385 local->tmp_channel = NULL;
386 ieee80211_hw_config(local, 0);
387
388 ieee80211_offchannel_return(local, true);
389 }
390
391 ieee80211_recalc_idle(local);
392
Alan Cox4b4b8222012-07-13 16:14:45 +0200393 if (started)
Johannes Berg0f6b3f52012-06-20 20:11:33 +0200394 ieee80211_start_next_roc(local);
Johannes Berg2eb278e2012-06-05 14:28:42 +0200395 }
396
397 out_unlock:
398 mutex_unlock(&local->mtx);
399}
400
Johannes Berg21f83582010-12-18 17:20:47 +0100401static void ieee80211_hw_roc_done(struct work_struct *work)
402{
403 struct ieee80211_local *local =
404 container_of(work, struct ieee80211_local, hw_roc_done);
Johannes Berg2eb278e2012-06-05 14:28:42 +0200405 struct ieee80211_roc_work *roc;
Johannes Berg21f83582010-12-18 17:20:47 +0100406
407 mutex_lock(&local->mtx);
408
Johannes Berg2eb278e2012-06-05 14:28:42 +0200409 if (list_empty(&local->roc_list))
410 goto out_unlock;
Johannes Berg21f83582010-12-18 17:20:47 +0100411
Johannes Berg2eb278e2012-06-05 14:28:42 +0200412 roc = list_first_entry(&local->roc_list, struct ieee80211_roc_work,
413 list);
Johannes Berg71ecfa12012-05-31 15:09:27 +0200414
Johannes Berg2eb278e2012-06-05 14:28:42 +0200415 if (!roc->started)
416 goto out_unlock;
Johannes Berg71ecfa12012-05-31 15:09:27 +0200417
Johannes Berg2eb278e2012-06-05 14:28:42 +0200418 list_del(&roc->list);
Johannes Berg71ecfa12012-05-31 15:09:27 +0200419
Johannes Berg2eb278e2012-06-05 14:28:42 +0200420 ieee80211_roc_notify_destroy(roc);
Johannes Berg71ecfa12012-05-31 15:09:27 +0200421
Johannes Berg2eb278e2012-06-05 14:28:42 +0200422 /* if there's another roc, start it now */
423 ieee80211_start_next_roc(local);
Johannes Berg21f83582010-12-18 17:20:47 +0100424
Johannes Berg2eb278e2012-06-05 14:28:42 +0200425 out_unlock:
Johannes Berg21f83582010-12-18 17:20:47 +0100426 mutex_unlock(&local->mtx);
427}
428
429void ieee80211_remain_on_channel_expired(struct ieee80211_hw *hw)
430{
431 struct ieee80211_local *local = hw_to_local(hw);
432
433 trace_api_remain_on_channel_expired(local);
434
435 ieee80211_queue_work(hw, &local->hw_roc_done);
436}
437EXPORT_SYMBOL_GPL(ieee80211_remain_on_channel_expired);
438
Johannes Berg2eb278e2012-06-05 14:28:42 +0200439void ieee80211_roc_setup(struct ieee80211_local *local)
Johannes Berg21f83582010-12-18 17:20:47 +0100440{
441 INIT_WORK(&local->hw_roc_start, ieee80211_hw_roc_start);
442 INIT_WORK(&local->hw_roc_done, ieee80211_hw_roc_done);
Johannes Berg2eb278e2012-06-05 14:28:42 +0200443 INIT_LIST_HEAD(&local->roc_list);
444}
445
446void ieee80211_roc_purge(struct ieee80211_sub_if_data *sdata)
447{
448 struct ieee80211_local *local = sdata->local;
449 struct ieee80211_roc_work *roc, *tmp;
450 LIST_HEAD(tmp_list);
451
452 mutex_lock(&local->mtx);
453 list_for_each_entry_safe(roc, tmp, &local->roc_list, list) {
454 if (roc->sdata != sdata)
455 continue;
456
457 if (roc->started && local->ops->remain_on_channel) {
458 /* can race, so ignore return value */
459 drv_cancel_remain_on_channel(local);
460 }
461
462 list_move_tail(&roc->list, &tmp_list);
463 roc->abort = true;
464 }
465
466 ieee80211_start_next_roc(local);
Johannes Berg2eb278e2012-06-05 14:28:42 +0200467 mutex_unlock(&local->mtx);
468
469 list_for_each_entry_safe(roc, tmp, &tmp_list, list) {
470 if (local->ops->remain_on_channel) {
471 list_del(&roc->list);
472 ieee80211_roc_notify_destroy(roc);
473 } else {
474 ieee80211_queue_delayed_work(&local->hw, &roc->work, 0);
475
476 /* work will clean up etc */
477 flush_delayed_work(&roc->work);
478 }
479 }
480
481 WARN_ON_ONCE(!list_empty(&tmp_list));
Johannes Berg21f83582010-12-18 17:20:47 +0100482}