xref: /linux/net/mac80211/mesh_hwmp.c (revision 005438a8eef063495ac059d128eea71b58de50e5)
1 /*
2  * Copyright (c) 2008, 2009 open80211s Ltd.
3  * Author:     Luis Carlos Cobo <luisca@cozybit.com>
4  *
5  * This program is free software; you can redistribute it and/or modify
6  * it under the terms of the GNU General Public License version 2 as
7  * published by the Free Software Foundation.
8  */
9 
10 #include <linux/slab.h>
11 #include <linux/etherdevice.h>
12 #include <asm/unaligned.h>
13 #include "wme.h"
14 #include "mesh.h"
15 
16 #define TEST_FRAME_LEN	8192
17 #define MAX_METRIC	0xffffffff
18 #define ARITH_SHIFT	8
19 
20 #define MAX_PREQ_QUEUE_LEN	64
21 
22 /* Destination only */
23 #define MP_F_DO	0x1
24 /* Reply and forward */
25 #define MP_F_RF	0x2
26 /* Unknown Sequence Number */
27 #define MP_F_USN    0x01
28 /* Reason code Present */
29 #define MP_F_RCODE  0x02
30 
31 static void mesh_queue_preq(struct mesh_path *, u8);
32 
33 static inline u32 u32_field_get(const u8 *preq_elem, int offset, bool ae)
34 {
35 	if (ae)
36 		offset += 6;
37 	return get_unaligned_le32(preq_elem + offset);
38 }
39 
40 static inline u16 u16_field_get(const u8 *preq_elem, int offset, bool ae)
41 {
42 	if (ae)
43 		offset += 6;
44 	return get_unaligned_le16(preq_elem + offset);
45 }
46 
47 /* HWMP IE processing macros */
48 #define AE_F			(1<<6)
49 #define AE_F_SET(x)		(*x & AE_F)
50 #define PREQ_IE_FLAGS(x)	(*(x))
51 #define PREQ_IE_HOPCOUNT(x)	(*(x + 1))
52 #define PREQ_IE_TTL(x)		(*(x + 2))
53 #define PREQ_IE_PREQ_ID(x)	u32_field_get(x, 3, 0)
54 #define PREQ_IE_ORIG_ADDR(x)	(x + 7)
55 #define PREQ_IE_ORIG_SN(x)	u32_field_get(x, 13, 0)
56 #define PREQ_IE_LIFETIME(x)	u32_field_get(x, 17, AE_F_SET(x))
57 #define PREQ_IE_METRIC(x) 	u32_field_get(x, 21, AE_F_SET(x))
58 #define PREQ_IE_TARGET_F(x)	(*(AE_F_SET(x) ? x + 32 : x + 26))
59 #define PREQ_IE_TARGET_ADDR(x) 	(AE_F_SET(x) ? x + 33 : x + 27)
60 #define PREQ_IE_TARGET_SN(x) 	u32_field_get(x, 33, AE_F_SET(x))
61 
62 
63 #define PREP_IE_FLAGS(x)	PREQ_IE_FLAGS(x)
64 #define PREP_IE_HOPCOUNT(x)	PREQ_IE_HOPCOUNT(x)
65 #define PREP_IE_TTL(x)		PREQ_IE_TTL(x)
66 #define PREP_IE_ORIG_ADDR(x)	(AE_F_SET(x) ? x + 27 : x + 21)
67 #define PREP_IE_ORIG_SN(x)	u32_field_get(x, 27, AE_F_SET(x))
68 #define PREP_IE_LIFETIME(x)	u32_field_get(x, 13, AE_F_SET(x))
69 #define PREP_IE_METRIC(x)	u32_field_get(x, 17, AE_F_SET(x))
70 #define PREP_IE_TARGET_ADDR(x)	(x + 3)
71 #define PREP_IE_TARGET_SN(x)	u32_field_get(x, 9, 0)
72 
73 #define PERR_IE_TTL(x)		(*(x))
74 #define PERR_IE_TARGET_FLAGS(x)	(*(x + 2))
75 #define PERR_IE_TARGET_ADDR(x)	(x + 3)
76 #define PERR_IE_TARGET_SN(x)	u32_field_get(x, 9, 0)
77 #define PERR_IE_TARGET_RCODE(x)	u16_field_get(x, 13, 0)
78 
79 #define MSEC_TO_TU(x) (x*1000/1024)
80 #define SN_GT(x, y) ((s32)(y - x) < 0)
81 #define SN_LT(x, y) ((s32)(x - y) < 0)
82 
83 #define net_traversal_jiffies(s) \
84 	msecs_to_jiffies(s->u.mesh.mshcfg.dot11MeshHWMPnetDiameterTraversalTime)
85 #define default_lifetime(s) \
86 	MSEC_TO_TU(s->u.mesh.mshcfg.dot11MeshHWMPactivePathTimeout)
87 #define min_preq_int_jiff(s) \
88 	(msecs_to_jiffies(s->u.mesh.mshcfg.dot11MeshHWMPpreqMinInterval))
89 #define max_preq_retries(s) (s->u.mesh.mshcfg.dot11MeshHWMPmaxPREQretries)
90 #define disc_timeout_jiff(s) \
91 	msecs_to_jiffies(sdata->u.mesh.mshcfg.min_discovery_timeout)
92 #define root_path_confirmation_jiffies(s) \
93 	msecs_to_jiffies(sdata->u.mesh.mshcfg.dot11MeshHWMPconfirmationInterval)
94 
95 enum mpath_frame_type {
96 	MPATH_PREQ = 0,
97 	MPATH_PREP,
98 	MPATH_PERR,
99 	MPATH_RANN
100 };
101 
102 static const u8 broadcast_addr[ETH_ALEN] = {0xff, 0xff, 0xff, 0xff, 0xff, 0xff};
103 
104 static int mesh_path_sel_frame_tx(enum mpath_frame_type action, u8 flags,
105 				  const u8 *orig_addr, u32 orig_sn,
106 				  u8 target_flags, const u8 *target,
107 				  u32 target_sn, const u8 *da,
108 				  u8 hop_count, u8 ttl,
109 				  u32 lifetime, u32 metric, u32 preq_id,
110 				  struct ieee80211_sub_if_data *sdata)
111 {
112 	struct ieee80211_local *local = sdata->local;
113 	struct sk_buff *skb;
114 	struct ieee80211_mgmt *mgmt;
115 	u8 *pos, ie_len;
116 	int hdr_len = offsetof(struct ieee80211_mgmt, u.action.u.mesh_action) +
117 		      sizeof(mgmt->u.action.u.mesh_action);
118 
119 	skb = dev_alloc_skb(local->tx_headroom +
120 			    hdr_len +
121 			    2 + 37); /* max HWMP IE */
122 	if (!skb)
123 		return -1;
124 	skb_reserve(skb, local->tx_headroom);
125 	mgmt = (struct ieee80211_mgmt *) skb_put(skb, hdr_len);
126 	memset(mgmt, 0, hdr_len);
127 	mgmt->frame_control = cpu_to_le16(IEEE80211_FTYPE_MGMT |
128 					  IEEE80211_STYPE_ACTION);
129 
130 	memcpy(mgmt->da, da, ETH_ALEN);
131 	memcpy(mgmt->sa, sdata->vif.addr, ETH_ALEN);
132 	/* BSSID == SA */
133 	memcpy(mgmt->bssid, sdata->vif.addr, ETH_ALEN);
134 	mgmt->u.action.category = WLAN_CATEGORY_MESH_ACTION;
135 	mgmt->u.action.u.mesh_action.action_code =
136 					WLAN_MESH_ACTION_HWMP_PATH_SELECTION;
137 
138 	switch (action) {
139 	case MPATH_PREQ:
140 		mhwmp_dbg(sdata, "sending PREQ to %pM\n", target);
141 		ie_len = 37;
142 		pos = skb_put(skb, 2 + ie_len);
143 		*pos++ = WLAN_EID_PREQ;
144 		break;
145 	case MPATH_PREP:
146 		mhwmp_dbg(sdata, "sending PREP to %pM\n", orig_addr);
147 		ie_len = 31;
148 		pos = skb_put(skb, 2 + ie_len);
149 		*pos++ = WLAN_EID_PREP;
150 		break;
151 	case MPATH_RANN:
152 		mhwmp_dbg(sdata, "sending RANN from %pM\n", orig_addr);
153 		ie_len = sizeof(struct ieee80211_rann_ie);
154 		pos = skb_put(skb, 2 + ie_len);
155 		*pos++ = WLAN_EID_RANN;
156 		break;
157 	default:
158 		kfree_skb(skb);
159 		return -ENOTSUPP;
160 	}
161 	*pos++ = ie_len;
162 	*pos++ = flags;
163 	*pos++ = hop_count;
164 	*pos++ = ttl;
165 	if (action == MPATH_PREP) {
166 		memcpy(pos, target, ETH_ALEN);
167 		pos += ETH_ALEN;
168 		put_unaligned_le32(target_sn, pos);
169 		pos += 4;
170 	} else {
171 		if (action == MPATH_PREQ) {
172 			put_unaligned_le32(preq_id, pos);
173 			pos += 4;
174 		}
175 		memcpy(pos, orig_addr, ETH_ALEN);
176 		pos += ETH_ALEN;
177 		put_unaligned_le32(orig_sn, pos);
178 		pos += 4;
179 	}
180 	put_unaligned_le32(lifetime, pos); /* interval for RANN */
181 	pos += 4;
182 	put_unaligned_le32(metric, pos);
183 	pos += 4;
184 	if (action == MPATH_PREQ) {
185 		*pos++ = 1; /* destination count */
186 		*pos++ = target_flags;
187 		memcpy(pos, target, ETH_ALEN);
188 		pos += ETH_ALEN;
189 		put_unaligned_le32(target_sn, pos);
190 		pos += 4;
191 	} else if (action == MPATH_PREP) {
192 		memcpy(pos, orig_addr, ETH_ALEN);
193 		pos += ETH_ALEN;
194 		put_unaligned_le32(orig_sn, pos);
195 		pos += 4;
196 	}
197 
198 	ieee80211_tx_skb(sdata, skb);
199 	return 0;
200 }
201 
202 
203 /*  Headroom is not adjusted.  Caller should ensure that skb has sufficient
204  *  headroom in case the frame is encrypted. */
205 static void prepare_frame_for_deferred_tx(struct ieee80211_sub_if_data *sdata,
206 		struct sk_buff *skb)
207 {
208 	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
209 	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
210 
211 	skb_set_mac_header(skb, 0);
212 	skb_set_network_header(skb, 0);
213 	skb_set_transport_header(skb, 0);
214 
215 	/* Send all internal mgmt frames on VO. Accordingly set TID to 7. */
216 	skb_set_queue_mapping(skb, IEEE80211_AC_VO);
217 	skb->priority = 7;
218 
219 	info->control.vif = &sdata->vif;
220 	info->flags |= IEEE80211_TX_INTFL_NEED_TXPROCESSING;
221 	ieee80211_set_qos_hdr(sdata, skb);
222 	ieee80211_mps_set_frame_flags(sdata, NULL, hdr);
223 }
224 
225 /**
226  * mesh_path_error_tx - Sends a PERR mesh management frame
227  *
228  * @ttl: allowed remaining hops
229  * @target: broken destination
230  * @target_sn: SN of the broken destination
231  * @target_rcode: reason code for this PERR
232  * @ra: node this frame is addressed to
233  * @sdata: local mesh subif
234  *
235  * Note: This function may be called with driver locks taken that the driver
236  * also acquires in the TX path.  To avoid a deadlock we don't transmit the
237  * frame directly but add it to the pending queue instead.
238  */
239 int mesh_path_error_tx(struct ieee80211_sub_if_data *sdata,
240 		       u8 ttl, const u8 *target, u32 target_sn,
241 		       u16 target_rcode, const u8 *ra)
242 {
243 	struct ieee80211_local *local = sdata->local;
244 	struct sk_buff *skb;
245 	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
246 	struct ieee80211_mgmt *mgmt;
247 	u8 *pos, ie_len;
248 	int hdr_len = offsetof(struct ieee80211_mgmt, u.action.u.mesh_action) +
249 		      sizeof(mgmt->u.action.u.mesh_action);
250 
251 	if (time_before(jiffies, ifmsh->next_perr))
252 		return -EAGAIN;
253 
254 	skb = dev_alloc_skb(local->tx_headroom +
255 			    sdata->encrypt_headroom +
256 			    IEEE80211_ENCRYPT_TAILROOM +
257 			    hdr_len +
258 			    2 + 15 /* PERR IE */);
259 	if (!skb)
260 		return -1;
261 	skb_reserve(skb, local->tx_headroom + sdata->encrypt_headroom);
262 	mgmt = (struct ieee80211_mgmt *) skb_put(skb, hdr_len);
263 	memset(mgmt, 0, hdr_len);
264 	mgmt->frame_control = cpu_to_le16(IEEE80211_FTYPE_MGMT |
265 					  IEEE80211_STYPE_ACTION);
266 
267 	memcpy(mgmt->da, ra, ETH_ALEN);
268 	memcpy(mgmt->sa, sdata->vif.addr, ETH_ALEN);
269 	/* BSSID == SA */
270 	memcpy(mgmt->bssid, sdata->vif.addr, ETH_ALEN);
271 	mgmt->u.action.category = WLAN_CATEGORY_MESH_ACTION;
272 	mgmt->u.action.u.mesh_action.action_code =
273 					WLAN_MESH_ACTION_HWMP_PATH_SELECTION;
274 	ie_len = 15;
275 	pos = skb_put(skb, 2 + ie_len);
276 	*pos++ = WLAN_EID_PERR;
277 	*pos++ = ie_len;
278 	/* ttl */
279 	*pos++ = ttl;
280 	/* number of destinations */
281 	*pos++ = 1;
282 	/*
283 	 * flags bit, bit 1 is unset if we know the sequence number and
284 	 * bit 2 is set if we have a reason code
285 	 */
286 	*pos = 0;
287 	if (!target_sn)
288 		*pos |= MP_F_USN;
289 	if (target_rcode)
290 		*pos |= MP_F_RCODE;
291 	pos++;
292 	memcpy(pos, target, ETH_ALEN);
293 	pos += ETH_ALEN;
294 	put_unaligned_le32(target_sn, pos);
295 	pos += 4;
296 	put_unaligned_le16(target_rcode, pos);
297 
298 	/* see note in function header */
299 	prepare_frame_for_deferred_tx(sdata, skb);
300 	ifmsh->next_perr = TU_TO_EXP_TIME(
301 				   ifmsh->mshcfg.dot11MeshHWMPperrMinInterval);
302 	ieee80211_add_pending_skb(local, skb);
303 	return 0;
304 }
305 
306 void ieee80211s_update_metric(struct ieee80211_local *local,
307 		struct sta_info *sta, struct sk_buff *skb)
308 {
309 	struct ieee80211_tx_info *txinfo = IEEE80211_SKB_CB(skb);
310 	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
311 	int failed;
312 
313 	if (!ieee80211_is_data(hdr->frame_control))
314 		return;
315 
316 	failed = !(txinfo->flags & IEEE80211_TX_STAT_ACK);
317 
318 	/* moving average, scaled to 100 */
319 	sta->fail_avg = ((80 * sta->fail_avg + 5) / 100 + 20 * failed);
320 	if (sta->fail_avg > 95)
321 		mesh_plink_broken(sta);
322 }
323 
324 static u32 airtime_link_metric_get(struct ieee80211_local *local,
325 				   struct sta_info *sta)
326 {
327 	struct rate_info rinfo;
328 	/* This should be adjusted for each device */
329 	int device_constant = 1 << ARITH_SHIFT;
330 	int test_frame_len = TEST_FRAME_LEN << ARITH_SHIFT;
331 	int s_unit = 1 << ARITH_SHIFT;
332 	int rate, err;
333 	u32 tx_time, estimated_retx;
334 	u64 result;
335 
336 	if (sta->fail_avg >= 100)
337 		return MAX_METRIC;
338 
339 	sta_set_rate_info_tx(sta, &sta->last_tx_rate, &rinfo);
340 	rate = cfg80211_calculate_bitrate(&rinfo);
341 	if (WARN_ON(!rate))
342 		return MAX_METRIC;
343 
344 	err = (sta->fail_avg << ARITH_SHIFT) / 100;
345 
346 	/* bitrate is in units of 100 Kbps, while we need rate in units of
347 	 * 1Mbps. This will be corrected on tx_time computation.
348 	 */
349 	tx_time = (device_constant + 10 * test_frame_len / rate);
350 	estimated_retx = ((1 << (2 * ARITH_SHIFT)) / (s_unit - err));
351 	result = (tx_time * estimated_retx) >> (2 * ARITH_SHIFT) ;
352 	return (u32)result;
353 }
354 
355 /**
356  * hwmp_route_info_get - Update routing info to originator and transmitter
357  *
358  * @sdata: local mesh subif
359  * @mgmt: mesh management frame
360  * @hwmp_ie: hwmp information element (PREP or PREQ)
361  * @action: type of hwmp ie
362  *
363  * This function updates the path routing information to the originator and the
364  * transmitter of a HWMP PREQ or PREP frame.
365  *
366  * Returns: metric to frame originator or 0 if the frame should not be further
367  * processed
368  *
369  * Notes: this function is the only place (besides user-provided info) where
370  * path routing information is updated.
371  */
372 static u32 hwmp_route_info_get(struct ieee80211_sub_if_data *sdata,
373 			       struct ieee80211_mgmt *mgmt,
374 			       const u8 *hwmp_ie, enum mpath_frame_type action)
375 {
376 	struct ieee80211_local *local = sdata->local;
377 	struct mesh_path *mpath;
378 	struct sta_info *sta;
379 	bool fresh_info;
380 	const u8 *orig_addr, *ta;
381 	u32 orig_sn, orig_metric;
382 	unsigned long orig_lifetime, exp_time;
383 	u32 last_hop_metric, new_metric;
384 	bool process = true;
385 
386 	rcu_read_lock();
387 	sta = sta_info_get(sdata, mgmt->sa);
388 	if (!sta) {
389 		rcu_read_unlock();
390 		return 0;
391 	}
392 
393 	last_hop_metric = airtime_link_metric_get(local, sta);
394 	/* Update and check originator routing info */
395 	fresh_info = true;
396 
397 	switch (action) {
398 	case MPATH_PREQ:
399 		orig_addr = PREQ_IE_ORIG_ADDR(hwmp_ie);
400 		orig_sn = PREQ_IE_ORIG_SN(hwmp_ie);
401 		orig_lifetime = PREQ_IE_LIFETIME(hwmp_ie);
402 		orig_metric = PREQ_IE_METRIC(hwmp_ie);
403 		break;
404 	case MPATH_PREP:
405 		/* Originator here refers to the MP that was the target in the
406 		 * Path Request. We divert from the nomenclature in the draft
407 		 * so that we can easily use a single function to gather path
408 		 * information from both PREQ and PREP frames.
409 		 */
410 		orig_addr = PREP_IE_TARGET_ADDR(hwmp_ie);
411 		orig_sn = PREP_IE_TARGET_SN(hwmp_ie);
412 		orig_lifetime = PREP_IE_LIFETIME(hwmp_ie);
413 		orig_metric = PREP_IE_METRIC(hwmp_ie);
414 		break;
415 	default:
416 		rcu_read_unlock();
417 		return 0;
418 	}
419 	new_metric = orig_metric + last_hop_metric;
420 	if (new_metric < orig_metric)
421 		new_metric = MAX_METRIC;
422 	exp_time = TU_TO_EXP_TIME(orig_lifetime);
423 
424 	if (ether_addr_equal(orig_addr, sdata->vif.addr)) {
425 		/* This MP is the originator, we are not interested in this
426 		 * frame, except for updating transmitter's path info.
427 		 */
428 		process = false;
429 		fresh_info = false;
430 	} else {
431 		mpath = mesh_path_lookup(sdata, orig_addr);
432 		if (mpath) {
433 			spin_lock_bh(&mpath->state_lock);
434 			if (mpath->flags & MESH_PATH_FIXED)
435 				fresh_info = false;
436 			else if ((mpath->flags & MESH_PATH_ACTIVE) &&
437 			    (mpath->flags & MESH_PATH_SN_VALID)) {
438 				if (SN_GT(mpath->sn, orig_sn) ||
439 				    (mpath->sn == orig_sn &&
440 				     new_metric >= mpath->metric)) {
441 					process = false;
442 					fresh_info = false;
443 				}
444 			}
445 		} else {
446 			mpath = mesh_path_add(sdata, orig_addr);
447 			if (IS_ERR(mpath)) {
448 				rcu_read_unlock();
449 				return 0;
450 			}
451 			spin_lock_bh(&mpath->state_lock);
452 		}
453 
454 		if (fresh_info) {
455 			mesh_path_assign_nexthop(mpath, sta);
456 			mpath->flags |= MESH_PATH_SN_VALID;
457 			mpath->metric = new_metric;
458 			mpath->sn = orig_sn;
459 			mpath->exp_time = time_after(mpath->exp_time, exp_time)
460 					  ?  mpath->exp_time : exp_time;
461 			mesh_path_activate(mpath);
462 			spin_unlock_bh(&mpath->state_lock);
463 			mesh_path_tx_pending(mpath);
464 			/* draft says preq_id should be saved to, but there does
465 			 * not seem to be any use for it, skipping by now
466 			 */
467 		} else
468 			spin_unlock_bh(&mpath->state_lock);
469 	}
470 
471 	/* Update and check transmitter routing info */
472 	ta = mgmt->sa;
473 	if (ether_addr_equal(orig_addr, ta))
474 		fresh_info = false;
475 	else {
476 		fresh_info = true;
477 
478 		mpath = mesh_path_lookup(sdata, ta);
479 		if (mpath) {
480 			spin_lock_bh(&mpath->state_lock);
481 			if ((mpath->flags & MESH_PATH_FIXED) ||
482 				((mpath->flags & MESH_PATH_ACTIVE) &&
483 					(last_hop_metric > mpath->metric)))
484 				fresh_info = false;
485 		} else {
486 			mpath = mesh_path_add(sdata, ta);
487 			if (IS_ERR(mpath)) {
488 				rcu_read_unlock();
489 				return 0;
490 			}
491 			spin_lock_bh(&mpath->state_lock);
492 		}
493 
494 		if (fresh_info) {
495 			mesh_path_assign_nexthop(mpath, sta);
496 			mpath->metric = last_hop_metric;
497 			mpath->exp_time = time_after(mpath->exp_time, exp_time)
498 					  ?  mpath->exp_time : exp_time;
499 			mesh_path_activate(mpath);
500 			spin_unlock_bh(&mpath->state_lock);
501 			mesh_path_tx_pending(mpath);
502 		} else
503 			spin_unlock_bh(&mpath->state_lock);
504 	}
505 
506 	rcu_read_unlock();
507 
508 	return process ? new_metric : 0;
509 }
510 
511 static void hwmp_preq_frame_process(struct ieee80211_sub_if_data *sdata,
512 				    struct ieee80211_mgmt *mgmt,
513 				    const u8 *preq_elem, u32 orig_metric)
514 {
515 	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
516 	struct mesh_path *mpath = NULL;
517 	const u8 *target_addr, *orig_addr;
518 	const u8 *da;
519 	u8 target_flags, ttl, flags;
520 	u32 orig_sn, target_sn, lifetime, target_metric;
521 	bool reply = false;
522 	bool forward = true;
523 	bool root_is_gate;
524 
525 	/* Update target SN, if present */
526 	target_addr = PREQ_IE_TARGET_ADDR(preq_elem);
527 	orig_addr = PREQ_IE_ORIG_ADDR(preq_elem);
528 	target_sn = PREQ_IE_TARGET_SN(preq_elem);
529 	orig_sn = PREQ_IE_ORIG_SN(preq_elem);
530 	target_flags = PREQ_IE_TARGET_F(preq_elem);
531 	/* Proactive PREQ gate announcements */
532 	flags = PREQ_IE_FLAGS(preq_elem);
533 	root_is_gate = !!(flags & RANN_FLAG_IS_GATE);
534 
535 	mhwmp_dbg(sdata, "received PREQ from %pM\n", orig_addr);
536 
537 	if (ether_addr_equal(target_addr, sdata->vif.addr)) {
538 		mhwmp_dbg(sdata, "PREQ is for us\n");
539 		forward = false;
540 		reply = true;
541 		target_metric = 0;
542 		if (time_after(jiffies, ifmsh->last_sn_update +
543 					net_traversal_jiffies(sdata)) ||
544 		    time_before(jiffies, ifmsh->last_sn_update)) {
545 			++ifmsh->sn;
546 			ifmsh->last_sn_update = jiffies;
547 		}
548 		target_sn = ifmsh->sn;
549 	} else if (is_broadcast_ether_addr(target_addr) &&
550 		   (target_flags & IEEE80211_PREQ_TO_FLAG)) {
551 		rcu_read_lock();
552 		mpath = mesh_path_lookup(sdata, orig_addr);
553 		if (mpath) {
554 			if (flags & IEEE80211_PREQ_PROACTIVE_PREP_FLAG) {
555 				reply = true;
556 				target_addr = sdata->vif.addr;
557 				target_sn = ++ifmsh->sn;
558 				target_metric = 0;
559 				ifmsh->last_sn_update = jiffies;
560 			}
561 			if (root_is_gate)
562 				mesh_path_add_gate(mpath);
563 		}
564 		rcu_read_unlock();
565 	} else {
566 		rcu_read_lock();
567 		mpath = mesh_path_lookup(sdata, target_addr);
568 		if (mpath) {
569 			if ((!(mpath->flags & MESH_PATH_SN_VALID)) ||
570 					SN_LT(mpath->sn, target_sn)) {
571 				mpath->sn = target_sn;
572 				mpath->flags |= MESH_PATH_SN_VALID;
573 			} else if ((!(target_flags & MP_F_DO)) &&
574 					(mpath->flags & MESH_PATH_ACTIVE)) {
575 				reply = true;
576 				target_metric = mpath->metric;
577 				target_sn = mpath->sn;
578 				if (target_flags & MP_F_RF)
579 					target_flags |= MP_F_DO;
580 				else
581 					forward = false;
582 			}
583 		}
584 		rcu_read_unlock();
585 	}
586 
587 	if (reply) {
588 		lifetime = PREQ_IE_LIFETIME(preq_elem);
589 		ttl = ifmsh->mshcfg.element_ttl;
590 		if (ttl != 0) {
591 			mhwmp_dbg(sdata, "replying to the PREQ\n");
592 			mesh_path_sel_frame_tx(MPATH_PREP, 0, orig_addr,
593 					       orig_sn, 0, target_addr,
594 					       target_sn, mgmt->sa, 0, ttl,
595 					       lifetime, target_metric, 0,
596 					       sdata);
597 		} else {
598 			ifmsh->mshstats.dropped_frames_ttl++;
599 		}
600 	}
601 
602 	if (forward && ifmsh->mshcfg.dot11MeshForwarding) {
603 		u32 preq_id;
604 		u8 hopcount;
605 
606 		ttl = PREQ_IE_TTL(preq_elem);
607 		lifetime = PREQ_IE_LIFETIME(preq_elem);
608 		if (ttl <= 1) {
609 			ifmsh->mshstats.dropped_frames_ttl++;
610 			return;
611 		}
612 		mhwmp_dbg(sdata, "forwarding the PREQ from %pM\n", orig_addr);
613 		--ttl;
614 		preq_id = PREQ_IE_PREQ_ID(preq_elem);
615 		hopcount = PREQ_IE_HOPCOUNT(preq_elem) + 1;
616 		da = (mpath && mpath->is_root) ?
617 			mpath->rann_snd_addr : broadcast_addr;
618 
619 		if (flags & IEEE80211_PREQ_PROACTIVE_PREP_FLAG) {
620 			target_addr = PREQ_IE_TARGET_ADDR(preq_elem);
621 			target_sn = PREQ_IE_TARGET_SN(preq_elem);
622 		}
623 
624 		mesh_path_sel_frame_tx(MPATH_PREQ, flags, orig_addr,
625 				       orig_sn, target_flags, target_addr,
626 				       target_sn, da, hopcount, ttl, lifetime,
627 				       orig_metric, preq_id, sdata);
628 		if (!is_multicast_ether_addr(da))
629 			ifmsh->mshstats.fwded_unicast++;
630 		else
631 			ifmsh->mshstats.fwded_mcast++;
632 		ifmsh->mshstats.fwded_frames++;
633 	}
634 }
635 
636 
637 static inline struct sta_info *
638 next_hop_deref_protected(struct mesh_path *mpath)
639 {
640 	return rcu_dereference_protected(mpath->next_hop,
641 					 lockdep_is_held(&mpath->state_lock));
642 }
643 
644 
645 static void hwmp_prep_frame_process(struct ieee80211_sub_if_data *sdata,
646 				    struct ieee80211_mgmt *mgmt,
647 				    const u8 *prep_elem, u32 metric)
648 {
649 	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
650 	struct mesh_path *mpath;
651 	const u8 *target_addr, *orig_addr;
652 	u8 ttl, hopcount, flags;
653 	u8 next_hop[ETH_ALEN];
654 	u32 target_sn, orig_sn, lifetime;
655 
656 	mhwmp_dbg(sdata, "received PREP from %pM\n",
657 		  PREP_IE_TARGET_ADDR(prep_elem));
658 
659 	orig_addr = PREP_IE_ORIG_ADDR(prep_elem);
660 	if (ether_addr_equal(orig_addr, sdata->vif.addr))
661 		/* destination, no forwarding required */
662 		return;
663 
664 	if (!ifmsh->mshcfg.dot11MeshForwarding)
665 		return;
666 
667 	ttl = PREP_IE_TTL(prep_elem);
668 	if (ttl <= 1) {
669 		sdata->u.mesh.mshstats.dropped_frames_ttl++;
670 		return;
671 	}
672 
673 	rcu_read_lock();
674 	mpath = mesh_path_lookup(sdata, orig_addr);
675 	if (mpath)
676 		spin_lock_bh(&mpath->state_lock);
677 	else
678 		goto fail;
679 	if (!(mpath->flags & MESH_PATH_ACTIVE)) {
680 		spin_unlock_bh(&mpath->state_lock);
681 		goto fail;
682 	}
683 	memcpy(next_hop, next_hop_deref_protected(mpath)->sta.addr, ETH_ALEN);
684 	spin_unlock_bh(&mpath->state_lock);
685 	--ttl;
686 	flags = PREP_IE_FLAGS(prep_elem);
687 	lifetime = PREP_IE_LIFETIME(prep_elem);
688 	hopcount = PREP_IE_HOPCOUNT(prep_elem) + 1;
689 	target_addr = PREP_IE_TARGET_ADDR(prep_elem);
690 	target_sn = PREP_IE_TARGET_SN(prep_elem);
691 	orig_sn = PREP_IE_ORIG_SN(prep_elem);
692 
693 	mesh_path_sel_frame_tx(MPATH_PREP, flags, orig_addr, orig_sn, 0,
694 			       target_addr, target_sn, next_hop, hopcount,
695 			       ttl, lifetime, metric, 0, sdata);
696 	rcu_read_unlock();
697 
698 	sdata->u.mesh.mshstats.fwded_unicast++;
699 	sdata->u.mesh.mshstats.fwded_frames++;
700 	return;
701 
702 fail:
703 	rcu_read_unlock();
704 	sdata->u.mesh.mshstats.dropped_frames_no_route++;
705 }
706 
707 static void hwmp_perr_frame_process(struct ieee80211_sub_if_data *sdata,
708 				    struct ieee80211_mgmt *mgmt,
709 				    const u8 *perr_elem)
710 {
711 	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
712 	struct mesh_path *mpath;
713 	u8 ttl;
714 	const u8 *ta, *target_addr;
715 	u32 target_sn;
716 	u16 target_rcode;
717 
718 	ta = mgmt->sa;
719 	ttl = PERR_IE_TTL(perr_elem);
720 	if (ttl <= 1) {
721 		ifmsh->mshstats.dropped_frames_ttl++;
722 		return;
723 	}
724 	ttl--;
725 	target_addr = PERR_IE_TARGET_ADDR(perr_elem);
726 	target_sn = PERR_IE_TARGET_SN(perr_elem);
727 	target_rcode = PERR_IE_TARGET_RCODE(perr_elem);
728 
729 	rcu_read_lock();
730 	mpath = mesh_path_lookup(sdata, target_addr);
731 	if (mpath) {
732 		struct sta_info *sta;
733 
734 		spin_lock_bh(&mpath->state_lock);
735 		sta = next_hop_deref_protected(mpath);
736 		if (mpath->flags & MESH_PATH_ACTIVE &&
737 		    ether_addr_equal(ta, sta->sta.addr) &&
738 		    (!(mpath->flags & MESH_PATH_SN_VALID) ||
739 		    SN_GT(target_sn, mpath->sn))) {
740 			mpath->flags &= ~MESH_PATH_ACTIVE;
741 			mpath->sn = target_sn;
742 			spin_unlock_bh(&mpath->state_lock);
743 			if (!ifmsh->mshcfg.dot11MeshForwarding)
744 				goto endperr;
745 			mesh_path_error_tx(sdata, ttl, target_addr,
746 					   target_sn, target_rcode,
747 					   broadcast_addr);
748 		} else
749 			spin_unlock_bh(&mpath->state_lock);
750 	}
751 endperr:
752 	rcu_read_unlock();
753 }
754 
755 static void hwmp_rann_frame_process(struct ieee80211_sub_if_data *sdata,
756 				    struct ieee80211_mgmt *mgmt,
757 				    const struct ieee80211_rann_ie *rann)
758 {
759 	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
760 	struct ieee80211_local *local = sdata->local;
761 	struct sta_info *sta;
762 	struct mesh_path *mpath;
763 	u8 ttl, flags, hopcount;
764 	const u8 *orig_addr;
765 	u32 orig_sn, metric, metric_txsta, interval;
766 	bool root_is_gate;
767 
768 	ttl = rann->rann_ttl;
769 	flags = rann->rann_flags;
770 	root_is_gate = !!(flags & RANN_FLAG_IS_GATE);
771 	orig_addr = rann->rann_addr;
772 	orig_sn = le32_to_cpu(rann->rann_seq);
773 	interval = le32_to_cpu(rann->rann_interval);
774 	hopcount = rann->rann_hopcount;
775 	hopcount++;
776 	metric = le32_to_cpu(rann->rann_metric);
777 
778 	/*  Ignore our own RANNs */
779 	if (ether_addr_equal(orig_addr, sdata->vif.addr))
780 		return;
781 
782 	mhwmp_dbg(sdata,
783 		  "received RANN from %pM via neighbour %pM (is_gate=%d)\n",
784 		  orig_addr, mgmt->sa, root_is_gate);
785 
786 	rcu_read_lock();
787 	sta = sta_info_get(sdata, mgmt->sa);
788 	if (!sta) {
789 		rcu_read_unlock();
790 		return;
791 	}
792 
793 	metric_txsta = airtime_link_metric_get(local, sta);
794 
795 	mpath = mesh_path_lookup(sdata, orig_addr);
796 	if (!mpath) {
797 		mpath = mesh_path_add(sdata, orig_addr);
798 		if (IS_ERR(mpath)) {
799 			rcu_read_unlock();
800 			sdata->u.mesh.mshstats.dropped_frames_no_route++;
801 			return;
802 		}
803 	}
804 
805 	if (!(SN_LT(mpath->sn, orig_sn)) &&
806 	    !(mpath->sn == orig_sn && metric < mpath->rann_metric)) {
807 		rcu_read_unlock();
808 		return;
809 	}
810 
811 	if ((!(mpath->flags & (MESH_PATH_ACTIVE | MESH_PATH_RESOLVING)) ||
812 	     (time_after(jiffies, mpath->last_preq_to_root +
813 				  root_path_confirmation_jiffies(sdata)) ||
814 	     time_before(jiffies, mpath->last_preq_to_root))) &&
815 	     !(mpath->flags & MESH_PATH_FIXED) && (ttl != 0)) {
816 		mhwmp_dbg(sdata,
817 			  "time to refresh root mpath %pM\n",
818 			  orig_addr);
819 		mesh_queue_preq(mpath, PREQ_Q_F_START | PREQ_Q_F_REFRESH);
820 		mpath->last_preq_to_root = jiffies;
821 	}
822 
823 	mpath->sn = orig_sn;
824 	mpath->rann_metric = metric + metric_txsta;
825 	mpath->is_root = true;
826 	/* Recording RANNs sender address to send individually
827 	 * addressed PREQs destined for root mesh STA */
828 	memcpy(mpath->rann_snd_addr, mgmt->sa, ETH_ALEN);
829 
830 	if (root_is_gate)
831 		mesh_path_add_gate(mpath);
832 
833 	if (ttl <= 1) {
834 		ifmsh->mshstats.dropped_frames_ttl++;
835 		rcu_read_unlock();
836 		return;
837 	}
838 	ttl--;
839 
840 	if (ifmsh->mshcfg.dot11MeshForwarding) {
841 		mesh_path_sel_frame_tx(MPATH_RANN, flags, orig_addr,
842 				       orig_sn, 0, NULL, 0, broadcast_addr,
843 				       hopcount, ttl, interval,
844 				       metric + metric_txsta, 0, sdata);
845 	}
846 
847 	rcu_read_unlock();
848 }
849 
850 
851 void mesh_rx_path_sel_frame(struct ieee80211_sub_if_data *sdata,
852 			    struct ieee80211_mgmt *mgmt, size_t len)
853 {
854 	struct ieee802_11_elems elems;
855 	size_t baselen;
856 	u32 path_metric;
857 	struct sta_info *sta;
858 
859 	/* need action_code */
860 	if (len < IEEE80211_MIN_ACTION_SIZE + 1)
861 		return;
862 
863 	rcu_read_lock();
864 	sta = sta_info_get(sdata, mgmt->sa);
865 	if (!sta || sta->plink_state != NL80211_PLINK_ESTAB) {
866 		rcu_read_unlock();
867 		return;
868 	}
869 	rcu_read_unlock();
870 
871 	baselen = (u8 *) mgmt->u.action.u.mesh_action.variable - (u8 *) mgmt;
872 	ieee802_11_parse_elems(mgmt->u.action.u.mesh_action.variable,
873 			       len - baselen, false, &elems);
874 
875 	if (elems.preq) {
876 		if (elems.preq_len != 37)
877 			/* Right now we support just 1 destination and no AE */
878 			return;
879 		path_metric = hwmp_route_info_get(sdata, mgmt, elems.preq,
880 						  MPATH_PREQ);
881 		if (path_metric)
882 			hwmp_preq_frame_process(sdata, mgmt, elems.preq,
883 						path_metric);
884 	}
885 	if (elems.prep) {
886 		if (elems.prep_len != 31)
887 			/* Right now we support no AE */
888 			return;
889 		path_metric = hwmp_route_info_get(sdata, mgmt, elems.prep,
890 						  MPATH_PREP);
891 		if (path_metric)
892 			hwmp_prep_frame_process(sdata, mgmt, elems.prep,
893 						path_metric);
894 	}
895 	if (elems.perr) {
896 		if (elems.perr_len != 15)
897 			/* Right now we support only one destination per PERR */
898 			return;
899 		hwmp_perr_frame_process(sdata, mgmt, elems.perr);
900 	}
901 	if (elems.rann)
902 		hwmp_rann_frame_process(sdata, mgmt, elems.rann);
903 }
904 
905 /**
906  * mesh_queue_preq - queue a PREQ to a given destination
907  *
908  * @mpath: mesh path to discover
909  * @flags: special attributes of the PREQ to be sent
910  *
911  * Locking: the function must be called from within a rcu read lock block.
912  *
913  */
914 static void mesh_queue_preq(struct mesh_path *mpath, u8 flags)
915 {
916 	struct ieee80211_sub_if_data *sdata = mpath->sdata;
917 	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
918 	struct mesh_preq_queue *preq_node;
919 
920 	preq_node = kmalloc(sizeof(struct mesh_preq_queue), GFP_ATOMIC);
921 	if (!preq_node) {
922 		mhwmp_dbg(sdata, "could not allocate PREQ node\n");
923 		return;
924 	}
925 
926 	spin_lock_bh(&ifmsh->mesh_preq_queue_lock);
927 	if (ifmsh->preq_queue_len == MAX_PREQ_QUEUE_LEN) {
928 		spin_unlock_bh(&ifmsh->mesh_preq_queue_lock);
929 		kfree(preq_node);
930 		if (printk_ratelimit())
931 			mhwmp_dbg(sdata, "PREQ node queue full\n");
932 		return;
933 	}
934 
935 	spin_lock(&mpath->state_lock);
936 	if (mpath->flags & MESH_PATH_REQ_QUEUED) {
937 		spin_unlock(&mpath->state_lock);
938 		spin_unlock_bh(&ifmsh->mesh_preq_queue_lock);
939 		kfree(preq_node);
940 		return;
941 	}
942 
943 	memcpy(preq_node->dst, mpath->dst, ETH_ALEN);
944 	preq_node->flags = flags;
945 
946 	mpath->flags |= MESH_PATH_REQ_QUEUED;
947 	spin_unlock(&mpath->state_lock);
948 
949 	list_add_tail(&preq_node->list, &ifmsh->preq_queue.list);
950 	++ifmsh->preq_queue_len;
951 	spin_unlock_bh(&ifmsh->mesh_preq_queue_lock);
952 
953 	if (time_after(jiffies, ifmsh->last_preq + min_preq_int_jiff(sdata)))
954 		ieee80211_queue_work(&sdata->local->hw, &sdata->work);
955 
956 	else if (time_before(jiffies, ifmsh->last_preq)) {
957 		/* avoid long wait if did not send preqs for a long time
958 		 * and jiffies wrapped around
959 		 */
960 		ifmsh->last_preq = jiffies - min_preq_int_jiff(sdata) - 1;
961 		ieee80211_queue_work(&sdata->local->hw, &sdata->work);
962 	} else
963 		mod_timer(&ifmsh->mesh_path_timer, ifmsh->last_preq +
964 						min_preq_int_jiff(sdata));
965 }
966 
967 /**
968  * mesh_path_start_discovery - launch a path discovery from the PREQ queue
969  *
970  * @sdata: local mesh subif
971  */
972 void mesh_path_start_discovery(struct ieee80211_sub_if_data *sdata)
973 {
974 	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
975 	struct mesh_preq_queue *preq_node;
976 	struct mesh_path *mpath;
977 	u8 ttl, target_flags;
978 	const u8 *da;
979 	u32 lifetime;
980 
981 	spin_lock_bh(&ifmsh->mesh_preq_queue_lock);
982 	if (!ifmsh->preq_queue_len ||
983 		time_before(jiffies, ifmsh->last_preq +
984 				min_preq_int_jiff(sdata))) {
985 		spin_unlock_bh(&ifmsh->mesh_preq_queue_lock);
986 		return;
987 	}
988 
989 	preq_node = list_first_entry(&ifmsh->preq_queue.list,
990 			struct mesh_preq_queue, list);
991 	list_del(&preq_node->list);
992 	--ifmsh->preq_queue_len;
993 	spin_unlock_bh(&ifmsh->mesh_preq_queue_lock);
994 
995 	rcu_read_lock();
996 	mpath = mesh_path_lookup(sdata, preq_node->dst);
997 	if (!mpath)
998 		goto enddiscovery;
999 
1000 	spin_lock_bh(&mpath->state_lock);
1001 	mpath->flags &= ~MESH_PATH_REQ_QUEUED;
1002 	if (preq_node->flags & PREQ_Q_F_START) {
1003 		if (mpath->flags & MESH_PATH_RESOLVING) {
1004 			spin_unlock_bh(&mpath->state_lock);
1005 			goto enddiscovery;
1006 		} else {
1007 			mpath->flags &= ~MESH_PATH_RESOLVED;
1008 			mpath->flags |= MESH_PATH_RESOLVING;
1009 			mpath->discovery_retries = 0;
1010 			mpath->discovery_timeout = disc_timeout_jiff(sdata);
1011 		}
1012 	} else if (!(mpath->flags & MESH_PATH_RESOLVING) ||
1013 			mpath->flags & MESH_PATH_RESOLVED) {
1014 		mpath->flags &= ~MESH_PATH_RESOLVING;
1015 		spin_unlock_bh(&mpath->state_lock);
1016 		goto enddiscovery;
1017 	}
1018 
1019 	ifmsh->last_preq = jiffies;
1020 
1021 	if (time_after(jiffies, ifmsh->last_sn_update +
1022 				net_traversal_jiffies(sdata)) ||
1023 	    time_before(jiffies, ifmsh->last_sn_update)) {
1024 		++ifmsh->sn;
1025 		sdata->u.mesh.last_sn_update = jiffies;
1026 	}
1027 	lifetime = default_lifetime(sdata);
1028 	ttl = sdata->u.mesh.mshcfg.element_ttl;
1029 	if (ttl == 0) {
1030 		sdata->u.mesh.mshstats.dropped_frames_ttl++;
1031 		spin_unlock_bh(&mpath->state_lock);
1032 		goto enddiscovery;
1033 	}
1034 
1035 	if (preq_node->flags & PREQ_Q_F_REFRESH)
1036 		target_flags = MP_F_DO;
1037 	else
1038 		target_flags = MP_F_RF;
1039 
1040 	spin_unlock_bh(&mpath->state_lock);
1041 	da = (mpath->is_root) ? mpath->rann_snd_addr : broadcast_addr;
1042 	mesh_path_sel_frame_tx(MPATH_PREQ, 0, sdata->vif.addr, ifmsh->sn,
1043 			       target_flags, mpath->dst, mpath->sn, da, 0,
1044 			       ttl, lifetime, 0, ifmsh->preq_id++, sdata);
1045 	mod_timer(&mpath->timer, jiffies + mpath->discovery_timeout);
1046 
1047 enddiscovery:
1048 	rcu_read_unlock();
1049 	kfree(preq_node);
1050 }
1051 
1052 /**
1053  * mesh_nexthop_resolve - lookup next hop; conditionally start path discovery
1054  *
1055  * @skb: 802.11 frame to be sent
1056  * @sdata: network subif the frame will be sent through
1057  *
1058  * Lookup next hop for given skb and start path discovery if no
1059  * forwarding information is found.
1060  *
1061  * Returns: 0 if the next hop was found and -ENOENT if the frame was queued.
1062  * skb is freeed here if no mpath could be allocated.
1063  */
1064 int mesh_nexthop_resolve(struct ieee80211_sub_if_data *sdata,
1065 			 struct sk_buff *skb)
1066 {
1067 	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
1068 	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
1069 	struct mesh_path *mpath;
1070 	struct sk_buff *skb_to_free = NULL;
1071 	u8 *target_addr = hdr->addr3;
1072 	int err = 0;
1073 
1074 	/* Nulls are only sent to peers for PS and should be pre-addressed */
1075 	if (ieee80211_is_qos_nullfunc(hdr->frame_control))
1076 		return 0;
1077 
1078 	rcu_read_lock();
1079 	err = mesh_nexthop_lookup(sdata, skb);
1080 	if (!err)
1081 		goto endlookup;
1082 
1083 	/* no nexthop found, start resolving */
1084 	mpath = mesh_path_lookup(sdata, target_addr);
1085 	if (!mpath) {
1086 		mpath = mesh_path_add(sdata, target_addr);
1087 		if (IS_ERR(mpath)) {
1088 			mesh_path_discard_frame(sdata, skb);
1089 			err = PTR_ERR(mpath);
1090 			goto endlookup;
1091 		}
1092 	}
1093 
1094 	if (!(mpath->flags & MESH_PATH_RESOLVING))
1095 		mesh_queue_preq(mpath, PREQ_Q_F_START);
1096 
1097 	if (skb_queue_len(&mpath->frame_queue) >= MESH_FRAME_QUEUE_LEN)
1098 		skb_to_free = skb_dequeue(&mpath->frame_queue);
1099 
1100 	info->flags |= IEEE80211_TX_INTFL_NEED_TXPROCESSING;
1101 	ieee80211_set_qos_hdr(sdata, skb);
1102 	skb_queue_tail(&mpath->frame_queue, skb);
1103 	err = -ENOENT;
1104 	if (skb_to_free)
1105 		mesh_path_discard_frame(sdata, skb_to_free);
1106 
1107 endlookup:
1108 	rcu_read_unlock();
1109 	return err;
1110 }
1111 
1112 /**
1113  * mesh_nexthop_lookup - put the appropriate next hop on a mesh frame. Calling
1114  * this function is considered "using" the associated mpath, so preempt a path
1115  * refresh if this mpath expires soon.
1116  *
1117  * @skb: 802.11 frame to be sent
1118  * @sdata: network subif the frame will be sent through
1119  *
1120  * Returns: 0 if the next hop was found. Nonzero otherwise.
1121  */
1122 int mesh_nexthop_lookup(struct ieee80211_sub_if_data *sdata,
1123 			struct sk_buff *skb)
1124 {
1125 	struct mesh_path *mpath;
1126 	struct sta_info *next_hop;
1127 	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
1128 	u8 *target_addr = hdr->addr3;
1129 	int err = -ENOENT;
1130 
1131 	rcu_read_lock();
1132 	mpath = mesh_path_lookup(sdata, target_addr);
1133 
1134 	if (!mpath || !(mpath->flags & MESH_PATH_ACTIVE))
1135 		goto endlookup;
1136 
1137 	if (time_after(jiffies,
1138 		       mpath->exp_time -
1139 		       msecs_to_jiffies(sdata->u.mesh.mshcfg.path_refresh_time)) &&
1140 	    ether_addr_equal(sdata->vif.addr, hdr->addr4) &&
1141 	    !(mpath->flags & MESH_PATH_RESOLVING) &&
1142 	    !(mpath->flags & MESH_PATH_FIXED))
1143 		mesh_queue_preq(mpath, PREQ_Q_F_START | PREQ_Q_F_REFRESH);
1144 
1145 	next_hop = rcu_dereference(mpath->next_hop);
1146 	if (next_hop) {
1147 		memcpy(hdr->addr1, next_hop->sta.addr, ETH_ALEN);
1148 		memcpy(hdr->addr2, sdata->vif.addr, ETH_ALEN);
1149 		ieee80211_mps_set_frame_flags(sdata, next_hop, hdr);
1150 		err = 0;
1151 	}
1152 
1153 endlookup:
1154 	rcu_read_unlock();
1155 	return err;
1156 }
1157 
1158 void mesh_path_timer(unsigned long data)
1159 {
1160 	struct mesh_path *mpath = (void *) data;
1161 	struct ieee80211_sub_if_data *sdata = mpath->sdata;
1162 	int ret;
1163 
1164 	if (sdata->local->quiescing)
1165 		return;
1166 
1167 	spin_lock_bh(&mpath->state_lock);
1168 	if (mpath->flags & MESH_PATH_RESOLVED ||
1169 			(!(mpath->flags & MESH_PATH_RESOLVING))) {
1170 		mpath->flags &= ~(MESH_PATH_RESOLVING | MESH_PATH_RESOLVED);
1171 		spin_unlock_bh(&mpath->state_lock);
1172 	} else if (mpath->discovery_retries < max_preq_retries(sdata)) {
1173 		++mpath->discovery_retries;
1174 		mpath->discovery_timeout *= 2;
1175 		mpath->flags &= ~MESH_PATH_REQ_QUEUED;
1176 		spin_unlock_bh(&mpath->state_lock);
1177 		mesh_queue_preq(mpath, 0);
1178 	} else {
1179 		mpath->flags = 0;
1180 		mpath->exp_time = jiffies;
1181 		spin_unlock_bh(&mpath->state_lock);
1182 		if (!mpath->is_gate && mesh_gate_num(sdata) > 0) {
1183 			ret = mesh_path_send_to_gates(mpath);
1184 			if (ret)
1185 				mhwmp_dbg(sdata, "no gate was reachable\n");
1186 		} else
1187 			mesh_path_flush_pending(mpath);
1188 	}
1189 }
1190 
1191 void mesh_path_tx_root_frame(struct ieee80211_sub_if_data *sdata)
1192 {
1193 	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
1194 	u32 interval = ifmsh->mshcfg.dot11MeshHWMPRannInterval;
1195 	u8 flags, target_flags = 0;
1196 
1197 	flags = (ifmsh->mshcfg.dot11MeshGateAnnouncementProtocol)
1198 			? RANN_FLAG_IS_GATE : 0;
1199 
1200 	switch (ifmsh->mshcfg.dot11MeshHWMPRootMode) {
1201 	case IEEE80211_PROACTIVE_RANN:
1202 		mesh_path_sel_frame_tx(MPATH_RANN, flags, sdata->vif.addr,
1203 				       ++ifmsh->sn, 0, NULL, 0, broadcast_addr,
1204 				       0, ifmsh->mshcfg.element_ttl,
1205 				       interval, 0, 0, sdata);
1206 		break;
1207 	case IEEE80211_PROACTIVE_PREQ_WITH_PREP:
1208 		flags |= IEEE80211_PREQ_PROACTIVE_PREP_FLAG;
1209 	case IEEE80211_PROACTIVE_PREQ_NO_PREP:
1210 		interval = ifmsh->mshcfg.dot11MeshHWMPactivePathToRootTimeout;
1211 		target_flags |= IEEE80211_PREQ_TO_FLAG |
1212 				IEEE80211_PREQ_USN_FLAG;
1213 		mesh_path_sel_frame_tx(MPATH_PREQ, flags, sdata->vif.addr,
1214 				       ++ifmsh->sn, target_flags,
1215 				       (u8 *) broadcast_addr, 0, broadcast_addr,
1216 				       0, ifmsh->mshcfg.element_ttl, interval,
1217 				       0, ifmsh->preq_id++, sdata);
1218 		break;
1219 	default:
1220 		mhwmp_dbg(sdata, "Proactive mechanism not supported\n");
1221 		return;
1222 	}
1223 }
1224