xref: /openbmc/linux/net/mac80211/mesh_hwmp.c (revision 95e9fd10)
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 /* Number of frames buffered per destination for unresolved destinations */
21 #define MESH_FRAME_QUEUE_LEN	10
22 #define MAX_PREQ_QUEUE_LEN	64
23 
24 /* Destination only */
25 #define MP_F_DO	0x1
26 /* Reply and forward */
27 #define MP_F_RF	0x2
28 /* Unknown Sequence Number */
29 #define MP_F_USN    0x01
30 /* Reason code Present */
31 #define MP_F_RCODE  0x02
32 
33 static void mesh_queue_preq(struct mesh_path *, u8);
34 
35 static inline u32 u32_field_get(u8 *preq_elem, int offset, bool ae)
36 {
37 	if (ae)
38 		offset += 6;
39 	return get_unaligned_le32(preq_elem + offset);
40 }
41 
42 static inline u32 u16_field_get(u8 *preq_elem, int offset, bool ae)
43 {
44 	if (ae)
45 		offset += 6;
46 	return get_unaligned_le16(preq_elem + offset);
47 }
48 
49 /* HWMP IE processing macros */
50 #define AE_F			(1<<6)
51 #define AE_F_SET(x)		(*x & AE_F)
52 #define PREQ_IE_FLAGS(x)	(*(x))
53 #define PREQ_IE_HOPCOUNT(x)	(*(x + 1))
54 #define PREQ_IE_TTL(x)		(*(x + 2))
55 #define PREQ_IE_PREQ_ID(x)	u32_field_get(x, 3, 0)
56 #define PREQ_IE_ORIG_ADDR(x)	(x + 7)
57 #define PREQ_IE_ORIG_SN(x)	u32_field_get(x, 13, 0)
58 #define PREQ_IE_LIFETIME(x)	u32_field_get(x, 17, AE_F_SET(x))
59 #define PREQ_IE_METRIC(x) 	u32_field_get(x, 21, AE_F_SET(x))
60 #define PREQ_IE_TARGET_F(x)	(*(AE_F_SET(x) ? x + 32 : x + 26))
61 #define PREQ_IE_TARGET_ADDR(x) 	(AE_F_SET(x) ? x + 33 : x + 27)
62 #define PREQ_IE_TARGET_SN(x) 	u32_field_get(x, 33, AE_F_SET(x))
63 
64 
65 #define PREP_IE_FLAGS(x)	PREQ_IE_FLAGS(x)
66 #define PREP_IE_HOPCOUNT(x)	PREQ_IE_HOPCOUNT(x)
67 #define PREP_IE_TTL(x)		PREQ_IE_TTL(x)
68 #define PREP_IE_ORIG_ADDR(x)	(AE_F_SET(x) ? x + 27 : x + 21)
69 #define PREP_IE_ORIG_SN(x)	u32_field_get(x, 27, AE_F_SET(x))
70 #define PREP_IE_LIFETIME(x)	u32_field_get(x, 13, AE_F_SET(x))
71 #define PREP_IE_METRIC(x)	u32_field_get(x, 17, AE_F_SET(x))
72 #define PREP_IE_TARGET_ADDR(x)	(x + 3)
73 #define PREP_IE_TARGET_SN(x)	u32_field_get(x, 9, 0)
74 
75 #define PERR_IE_TTL(x)		(*(x))
76 #define PERR_IE_TARGET_FLAGS(x)	(*(x + 2))
77 #define PERR_IE_TARGET_ADDR(x)	(x + 3)
78 #define PERR_IE_TARGET_SN(x)	u32_field_get(x, 9, 0)
79 #define PERR_IE_TARGET_RCODE(x)	u16_field_get(x, 13, 0)
80 
81 #define MSEC_TO_TU(x) (x*1000/1024)
82 #define SN_GT(x, y) ((s32)(y - x) < 0)
83 #define SN_LT(x, y) ((s32)(x - y) < 0)
84 
85 #define net_traversal_jiffies(s) \
86 	msecs_to_jiffies(s->u.mesh.mshcfg.dot11MeshHWMPnetDiameterTraversalTime)
87 #define default_lifetime(s) \
88 	MSEC_TO_TU(s->u.mesh.mshcfg.dot11MeshHWMPactivePathTimeout)
89 #define min_preq_int_jiff(s) \
90 	(msecs_to_jiffies(s->u.mesh.mshcfg.dot11MeshHWMPpreqMinInterval))
91 #define max_preq_retries(s) (s->u.mesh.mshcfg.dot11MeshHWMPmaxPREQretries)
92 #define disc_timeout_jiff(s) \
93 	msecs_to_jiffies(sdata->u.mesh.mshcfg.min_discovery_timeout)
94 #define root_path_confirmation_jiffies(s) \
95 	msecs_to_jiffies(sdata->u.mesh.mshcfg.dot11MeshHWMPconfirmationInterval)
96 
97 enum mpath_frame_type {
98 	MPATH_PREQ = 0,
99 	MPATH_PREP,
100 	MPATH_PERR,
101 	MPATH_RANN
102 };
103 
104 static const u8 broadcast_addr[ETH_ALEN] = {0xff, 0xff, 0xff, 0xff, 0xff, 0xff};
105 
106 static int mesh_path_sel_frame_tx(enum mpath_frame_type action, u8 flags,
107 		u8 *orig_addr, __le32 orig_sn, u8 target_flags, u8 *target,
108 		__le32 target_sn, const u8 *da, u8 hop_count, u8 ttl,
109 		__le32 lifetime, __le32 metric, __le32 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", target);
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 		break;
161 	}
162 	*pos++ = ie_len;
163 	*pos++ = flags;
164 	*pos++ = hop_count;
165 	*pos++ = ttl;
166 	if (action == MPATH_PREP) {
167 		memcpy(pos, target, ETH_ALEN);
168 		pos += ETH_ALEN;
169 		memcpy(pos, &target_sn, 4);
170 		pos += 4;
171 	} else {
172 		if (action == MPATH_PREQ) {
173 			memcpy(pos, &preq_id, 4);
174 			pos += 4;
175 		}
176 		memcpy(pos, orig_addr, ETH_ALEN);
177 		pos += ETH_ALEN;
178 		memcpy(pos, &orig_sn, 4);
179 		pos += 4;
180 	}
181 	memcpy(pos, &lifetime, 4);	/* interval for RANN */
182 	pos += 4;
183 	memcpy(pos, &metric, 4);
184 	pos += 4;
185 	if (action == MPATH_PREQ) {
186 		*pos++ = 1; /* destination count */
187 		*pos++ = target_flags;
188 		memcpy(pos, target, ETH_ALEN);
189 		pos += ETH_ALEN;
190 		memcpy(pos, &target_sn, 4);
191 		pos += 4;
192 	} else if (action == MPATH_PREP) {
193 		memcpy(pos, orig_addr, ETH_ALEN);
194 		pos += ETH_ALEN;
195 		memcpy(pos, &orig_sn, 4);
196 		pos += 4;
197 	}
198 
199 	ieee80211_tx_skb(sdata, skb);
200 	return 0;
201 }
202 
203 
204 /*  Headroom is not adjusted.  Caller should ensure that skb has sufficient
205  *  headroom in case the frame is encrypted. */
206 static void prepare_frame_for_deferred_tx(struct ieee80211_sub_if_data *sdata,
207 		struct sk_buff *skb)
208 {
209 	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
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 	ieee80211_set_qos_hdr(sdata, skb);
221 }
222 
223 /**
224  * mesh_send_path error - Sends a PERR mesh management frame
225  *
226  * @target: broken destination
227  * @target_sn: SN of the broken destination
228  * @target_rcode: reason code for this PERR
229  * @ra: node this frame is addressed to
230  *
231  * Note: This function may be called with driver locks taken that the driver
232  * also acquires in the TX path.  To avoid a deadlock we don't transmit the
233  * frame directly but add it to the pending queue instead.
234  */
235 int mesh_path_error_tx(u8 ttl, u8 *target, __le32 target_sn,
236 		       __le16 target_rcode, const u8 *ra,
237 		       struct ieee80211_sub_if_data *sdata)
238 {
239 	struct ieee80211_local *local = sdata->local;
240 	struct sk_buff *skb;
241 	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
242 	struct ieee80211_mgmt *mgmt;
243 	u8 *pos, ie_len;
244 	int hdr_len = offsetof(struct ieee80211_mgmt, u.action.u.mesh_action) +
245 		      sizeof(mgmt->u.action.u.mesh_action);
246 
247 	if (time_before(jiffies, ifmsh->next_perr))
248 		return -EAGAIN;
249 
250 	skb = dev_alloc_skb(local->tx_headroom +
251 			    hdr_len +
252 			    2 + 15 /* PERR IE */);
253 	if (!skb)
254 		return -1;
255 	skb_reserve(skb, local->tx_headroom);
256 	mgmt = (struct ieee80211_mgmt *) skb_put(skb, hdr_len);
257 	memset(mgmt, 0, hdr_len);
258 	mgmt->frame_control = cpu_to_le16(IEEE80211_FTYPE_MGMT |
259 					  IEEE80211_STYPE_ACTION);
260 
261 	memcpy(mgmt->da, ra, ETH_ALEN);
262 	memcpy(mgmt->sa, sdata->vif.addr, ETH_ALEN);
263 	/* BSSID == SA */
264 	memcpy(mgmt->bssid, sdata->vif.addr, ETH_ALEN);
265 	mgmt->u.action.category = WLAN_CATEGORY_MESH_ACTION;
266 	mgmt->u.action.u.mesh_action.action_code =
267 					WLAN_MESH_ACTION_HWMP_PATH_SELECTION;
268 	ie_len = 15;
269 	pos = skb_put(skb, 2 + ie_len);
270 	*pos++ = WLAN_EID_PERR;
271 	*pos++ = ie_len;
272 	/* ttl */
273 	*pos++ = ttl;
274 	/* number of destinations */
275 	*pos++ = 1;
276 	/*
277 	 * flags bit, bit 1 is unset if we know the sequence number and
278 	 * bit 2 is set if we have a reason code
279 	 */
280 	*pos = 0;
281 	if (!target_sn)
282 		*pos |= MP_F_USN;
283 	if (target_rcode)
284 		*pos |= MP_F_RCODE;
285 	pos++;
286 	memcpy(pos, target, ETH_ALEN);
287 	pos += ETH_ALEN;
288 	memcpy(pos, &target_sn, 4);
289 	pos += 4;
290 	memcpy(pos, &target_rcode, 2);
291 
292 	/* see note in function header */
293 	prepare_frame_for_deferred_tx(sdata, skb);
294 	ifmsh->next_perr = TU_TO_EXP_TIME(
295 				   ifmsh->mshcfg.dot11MeshHWMPperrMinInterval);
296 	ieee80211_add_pending_skb(local, skb);
297 	return 0;
298 }
299 
300 void ieee80211s_update_metric(struct ieee80211_local *local,
301 		struct sta_info *sta, struct sk_buff *skb)
302 {
303 	struct ieee80211_tx_info *txinfo = IEEE80211_SKB_CB(skb);
304 	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
305 	int failed;
306 
307 	if (!ieee80211_is_data(hdr->frame_control))
308 		return;
309 
310 	failed = !(txinfo->flags & IEEE80211_TX_STAT_ACK);
311 
312 	/* moving average, scaled to 100 */
313 	sta->fail_avg = ((80 * sta->fail_avg + 5) / 100 + 20 * failed);
314 	if (sta->fail_avg > 95)
315 		mesh_plink_broken(sta);
316 }
317 
318 static u32 airtime_link_metric_get(struct ieee80211_local *local,
319 				   struct sta_info *sta)
320 {
321 	struct rate_info rinfo;
322 	/* This should be adjusted for each device */
323 	int device_constant = 1 << ARITH_SHIFT;
324 	int test_frame_len = TEST_FRAME_LEN << ARITH_SHIFT;
325 	int s_unit = 1 << ARITH_SHIFT;
326 	int rate, err;
327 	u32 tx_time, estimated_retx;
328 	u64 result;
329 
330 	if (sta->fail_avg >= 100)
331 		return MAX_METRIC;
332 
333 	sta_set_rate_info_tx(sta, &sta->last_tx_rate, &rinfo);
334 	rate = cfg80211_calculate_bitrate(&rinfo);
335 	if (WARN_ON(!rate))
336 		return MAX_METRIC;
337 
338 	err = (sta->fail_avg << ARITH_SHIFT) / 100;
339 
340 	/* bitrate is in units of 100 Kbps, while we need rate in units of
341 	 * 1Mbps. This will be corrected on tx_time computation.
342 	 */
343 	tx_time = (device_constant + 10 * test_frame_len / rate);
344 	estimated_retx = ((1 << (2 * ARITH_SHIFT)) / (s_unit - err));
345 	result = (tx_time * estimated_retx) >> (2 * ARITH_SHIFT) ;
346 	return (u32)result;
347 }
348 
349 /**
350  * hwmp_route_info_get - Update routing info to originator and transmitter
351  *
352  * @sdata: local mesh subif
353  * @mgmt: mesh management frame
354  * @hwmp_ie: hwmp information element (PREP or PREQ)
355  *
356  * This function updates the path routing information to the originator and the
357  * transmitter of a HWMP PREQ or PREP frame.
358  *
359  * Returns: metric to frame originator or 0 if the frame should not be further
360  * processed
361  *
362  * Notes: this function is the only place (besides user-provided info) where
363  * path routing information is updated.
364  */
365 static u32 hwmp_route_info_get(struct ieee80211_sub_if_data *sdata,
366 			    struct ieee80211_mgmt *mgmt,
367 			    u8 *hwmp_ie, enum mpath_frame_type action)
368 {
369 	struct ieee80211_local *local = sdata->local;
370 	struct mesh_path *mpath;
371 	struct sta_info *sta;
372 	bool fresh_info;
373 	u8 *orig_addr, *ta;
374 	u32 orig_sn, orig_metric;
375 	unsigned long orig_lifetime, exp_time;
376 	u32 last_hop_metric, new_metric;
377 	bool process = true;
378 
379 	rcu_read_lock();
380 	sta = sta_info_get(sdata, mgmt->sa);
381 	if (!sta) {
382 		rcu_read_unlock();
383 		return 0;
384 	}
385 
386 	last_hop_metric = airtime_link_metric_get(local, sta);
387 	/* Update and check originator routing info */
388 	fresh_info = true;
389 
390 	switch (action) {
391 	case MPATH_PREQ:
392 		orig_addr = PREQ_IE_ORIG_ADDR(hwmp_ie);
393 		orig_sn = PREQ_IE_ORIG_SN(hwmp_ie);
394 		orig_lifetime = PREQ_IE_LIFETIME(hwmp_ie);
395 		orig_metric = PREQ_IE_METRIC(hwmp_ie);
396 		break;
397 	case MPATH_PREP:
398 		/* Originator here refers to the MP that was the target in the
399 		 * Path Request. We divert from the nomenclature in the draft
400 		 * so that we can easily use a single function to gather path
401 		 * information from both PREQ and PREP frames.
402 		 */
403 		orig_addr = PREP_IE_TARGET_ADDR(hwmp_ie);
404 		orig_sn = PREP_IE_TARGET_SN(hwmp_ie);
405 		orig_lifetime = PREP_IE_LIFETIME(hwmp_ie);
406 		orig_metric = PREP_IE_METRIC(hwmp_ie);
407 		break;
408 	default:
409 		rcu_read_unlock();
410 		return 0;
411 	}
412 	new_metric = orig_metric + last_hop_metric;
413 	if (new_metric < orig_metric)
414 		new_metric = MAX_METRIC;
415 	exp_time = TU_TO_EXP_TIME(orig_lifetime);
416 
417 	if (ether_addr_equal(orig_addr, sdata->vif.addr)) {
418 		/* This MP is the originator, we are not interested in this
419 		 * frame, except for updating transmitter's path info.
420 		 */
421 		process = false;
422 		fresh_info = false;
423 	} else {
424 		mpath = mesh_path_lookup(orig_addr, sdata);
425 		if (mpath) {
426 			spin_lock_bh(&mpath->state_lock);
427 			if (mpath->flags & MESH_PATH_FIXED)
428 				fresh_info = false;
429 			else if ((mpath->flags & MESH_PATH_ACTIVE) &&
430 			    (mpath->flags & MESH_PATH_SN_VALID)) {
431 				if (SN_GT(mpath->sn, orig_sn) ||
432 				    (mpath->sn == orig_sn &&
433 				     new_metric >= mpath->metric)) {
434 					process = false;
435 					fresh_info = false;
436 				}
437 			}
438 		} else {
439 			mesh_path_add(orig_addr, sdata);
440 			mpath = mesh_path_lookup(orig_addr, sdata);
441 			if (!mpath) {
442 				rcu_read_unlock();
443 				return 0;
444 			}
445 			spin_lock_bh(&mpath->state_lock);
446 		}
447 
448 		if (fresh_info) {
449 			mesh_path_assign_nexthop(mpath, sta);
450 			mpath->flags |= MESH_PATH_SN_VALID;
451 			mpath->metric = new_metric;
452 			mpath->sn = orig_sn;
453 			mpath->exp_time = time_after(mpath->exp_time, exp_time)
454 					  ?  mpath->exp_time : exp_time;
455 			mesh_path_activate(mpath);
456 			spin_unlock_bh(&mpath->state_lock);
457 			mesh_path_tx_pending(mpath);
458 			/* draft says preq_id should be saved to, but there does
459 			 * not seem to be any use for it, skipping by now
460 			 */
461 		} else
462 			spin_unlock_bh(&mpath->state_lock);
463 	}
464 
465 	/* Update and check transmitter routing info */
466 	ta = mgmt->sa;
467 	if (ether_addr_equal(orig_addr, ta))
468 		fresh_info = false;
469 	else {
470 		fresh_info = true;
471 
472 		mpath = mesh_path_lookup(ta, sdata);
473 		if (mpath) {
474 			spin_lock_bh(&mpath->state_lock);
475 			if ((mpath->flags & MESH_PATH_FIXED) ||
476 				((mpath->flags & MESH_PATH_ACTIVE) &&
477 					(last_hop_metric > mpath->metric)))
478 				fresh_info = false;
479 		} else {
480 			mesh_path_add(ta, sdata);
481 			mpath = mesh_path_lookup(ta, sdata);
482 			if (!mpath) {
483 				rcu_read_unlock();
484 				return 0;
485 			}
486 			spin_lock_bh(&mpath->state_lock);
487 		}
488 
489 		if (fresh_info) {
490 			mesh_path_assign_nexthop(mpath, sta);
491 			mpath->metric = last_hop_metric;
492 			mpath->exp_time = time_after(mpath->exp_time, exp_time)
493 					  ?  mpath->exp_time : exp_time;
494 			mesh_path_activate(mpath);
495 			spin_unlock_bh(&mpath->state_lock);
496 			mesh_path_tx_pending(mpath);
497 		} else
498 			spin_unlock_bh(&mpath->state_lock);
499 	}
500 
501 	rcu_read_unlock();
502 
503 	return process ? new_metric : 0;
504 }
505 
506 static void hwmp_preq_frame_process(struct ieee80211_sub_if_data *sdata,
507 				    struct ieee80211_mgmt *mgmt,
508 				    u8 *preq_elem, u32 metric)
509 {
510 	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
511 	struct mesh_path *mpath = NULL;
512 	u8 *target_addr, *orig_addr;
513 	const u8 *da;
514 	u8 target_flags, ttl, flags;
515 	u32 orig_sn, target_sn, lifetime, orig_metric;
516 	bool reply = false;
517 	bool forward = true;
518 	bool root_is_gate;
519 
520 	/* Update target SN, if present */
521 	target_addr = PREQ_IE_TARGET_ADDR(preq_elem);
522 	orig_addr = PREQ_IE_ORIG_ADDR(preq_elem);
523 	target_sn = PREQ_IE_TARGET_SN(preq_elem);
524 	orig_sn = PREQ_IE_ORIG_SN(preq_elem);
525 	target_flags = PREQ_IE_TARGET_F(preq_elem);
526 	orig_metric = metric;
527 	/* Proactive PREQ gate announcements */
528 	flags = PREQ_IE_FLAGS(preq_elem);
529 	root_is_gate = !!(flags & RANN_FLAG_IS_GATE);
530 
531 	mhwmp_dbg(sdata, "received PREQ from %pM\n", orig_addr);
532 
533 	if (ether_addr_equal(target_addr, sdata->vif.addr)) {
534 		mhwmp_dbg(sdata, "PREQ is for us\n");
535 		forward = false;
536 		reply = true;
537 		metric = 0;
538 		if (time_after(jiffies, ifmsh->last_sn_update +
539 					net_traversal_jiffies(sdata)) ||
540 		    time_before(jiffies, ifmsh->last_sn_update)) {
541 			target_sn = ++ifmsh->sn;
542 			ifmsh->last_sn_update = jiffies;
543 		}
544 	} else if (is_broadcast_ether_addr(target_addr) &&
545 		   (target_flags & IEEE80211_PREQ_TO_FLAG)) {
546 		rcu_read_lock();
547 		mpath = mesh_path_lookup(orig_addr, sdata);
548 		if (mpath) {
549 			if (flags & IEEE80211_PREQ_PROACTIVE_PREP_FLAG) {
550 				reply = true;
551 				target_addr = sdata->vif.addr;
552 				target_sn = ++ifmsh->sn;
553 				metric = 0;
554 				ifmsh->last_sn_update = jiffies;
555 			}
556 			if (root_is_gate)
557 				mesh_path_add_gate(mpath);
558 		}
559 		rcu_read_unlock();
560 	} else {
561 		rcu_read_lock();
562 		mpath = mesh_path_lookup(target_addr, sdata);
563 		if (mpath) {
564 			if ((!(mpath->flags & MESH_PATH_SN_VALID)) ||
565 					SN_LT(mpath->sn, target_sn)) {
566 				mpath->sn = target_sn;
567 				mpath->flags |= MESH_PATH_SN_VALID;
568 			} else if ((!(target_flags & MP_F_DO)) &&
569 					(mpath->flags & MESH_PATH_ACTIVE)) {
570 				reply = true;
571 				metric = mpath->metric;
572 				target_sn = mpath->sn;
573 				if (target_flags & MP_F_RF)
574 					target_flags |= MP_F_DO;
575 				else
576 					forward = false;
577 			}
578 		}
579 		rcu_read_unlock();
580 	}
581 
582 	if (reply) {
583 		lifetime = PREQ_IE_LIFETIME(preq_elem);
584 		ttl = ifmsh->mshcfg.element_ttl;
585 		if (ttl != 0) {
586 			mhwmp_dbg(sdata, "replying to the PREQ\n");
587 			mesh_path_sel_frame_tx(MPATH_PREP, 0, orig_addr,
588 				cpu_to_le32(orig_sn), 0, target_addr,
589 				cpu_to_le32(target_sn), mgmt->sa, 0, ttl,
590 				cpu_to_le32(lifetime), cpu_to_le32(metric),
591 				0, sdata);
592 		} else {
593 			ifmsh->mshstats.dropped_frames_ttl++;
594 		}
595 	}
596 
597 	if (forward && ifmsh->mshcfg.dot11MeshForwarding) {
598 		u32 preq_id;
599 		u8 hopcount;
600 
601 		ttl = PREQ_IE_TTL(preq_elem);
602 		lifetime = PREQ_IE_LIFETIME(preq_elem);
603 		if (ttl <= 1) {
604 			ifmsh->mshstats.dropped_frames_ttl++;
605 			return;
606 		}
607 		mhwmp_dbg(sdata, "forwarding the PREQ from %pM\n", orig_addr);
608 		--ttl;
609 		preq_id = PREQ_IE_PREQ_ID(preq_elem);
610 		hopcount = PREQ_IE_HOPCOUNT(preq_elem) + 1;
611 		da = (mpath && mpath->is_root) ?
612 			mpath->rann_snd_addr : broadcast_addr;
613 
614 		if (flags & IEEE80211_PREQ_PROACTIVE_PREP_FLAG) {
615 			target_addr = PREQ_IE_TARGET_ADDR(preq_elem);
616 			target_sn = PREQ_IE_TARGET_SN(preq_elem);
617 			metric = orig_metric;
618 		}
619 
620 		mesh_path_sel_frame_tx(MPATH_PREQ, flags, orig_addr,
621 				cpu_to_le32(orig_sn), target_flags, target_addr,
622 				cpu_to_le32(target_sn), da,
623 				hopcount, ttl, cpu_to_le32(lifetime),
624 				cpu_to_le32(metric), cpu_to_le32(preq_id),
625 				sdata);
626 		if (!is_multicast_ether_addr(da))
627 			ifmsh->mshstats.fwded_unicast++;
628 		else
629 			ifmsh->mshstats.fwded_mcast++;
630 		ifmsh->mshstats.fwded_frames++;
631 	}
632 }
633 
634 
635 static inline struct sta_info *
636 next_hop_deref_protected(struct mesh_path *mpath)
637 {
638 	return rcu_dereference_protected(mpath->next_hop,
639 					 lockdep_is_held(&mpath->state_lock));
640 }
641 
642 
643 static void hwmp_prep_frame_process(struct ieee80211_sub_if_data *sdata,
644 				    struct ieee80211_mgmt *mgmt,
645 				    u8 *prep_elem, u32 metric)
646 {
647 	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
648 	struct mesh_path *mpath;
649 	u8 *target_addr, *orig_addr;
650 	u8 ttl, hopcount, flags;
651 	u8 next_hop[ETH_ALEN];
652 	u32 target_sn, orig_sn, lifetime;
653 
654 	mhwmp_dbg(sdata, "received PREP from %pM\n",
655 		  PREP_IE_ORIG_ADDR(prep_elem));
656 
657 	orig_addr = PREP_IE_ORIG_ADDR(prep_elem);
658 	if (ether_addr_equal(orig_addr, sdata->vif.addr))
659 		/* destination, no forwarding required */
660 		return;
661 
662 	if (!ifmsh->mshcfg.dot11MeshForwarding)
663 		return;
664 
665 	ttl = PREP_IE_TTL(prep_elem);
666 	if (ttl <= 1) {
667 		sdata->u.mesh.mshstats.dropped_frames_ttl++;
668 		return;
669 	}
670 
671 	rcu_read_lock();
672 	mpath = mesh_path_lookup(orig_addr, sdata);
673 	if (mpath)
674 		spin_lock_bh(&mpath->state_lock);
675 	else
676 		goto fail;
677 	if (!(mpath->flags & MESH_PATH_ACTIVE)) {
678 		spin_unlock_bh(&mpath->state_lock);
679 		goto fail;
680 	}
681 	memcpy(next_hop, next_hop_deref_protected(mpath)->sta.addr, ETH_ALEN);
682 	spin_unlock_bh(&mpath->state_lock);
683 	--ttl;
684 	flags = PREP_IE_FLAGS(prep_elem);
685 	lifetime = PREP_IE_LIFETIME(prep_elem);
686 	hopcount = PREP_IE_HOPCOUNT(prep_elem) + 1;
687 	target_addr = PREP_IE_TARGET_ADDR(prep_elem);
688 	target_sn = PREP_IE_TARGET_SN(prep_elem);
689 	orig_sn = PREP_IE_ORIG_SN(prep_elem);
690 
691 	mesh_path_sel_frame_tx(MPATH_PREP, flags, orig_addr,
692 		cpu_to_le32(orig_sn), 0, target_addr,
693 		cpu_to_le32(target_sn), next_hop, hopcount,
694 		ttl, cpu_to_le32(lifetime), cpu_to_le32(metric),
695 		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, u8 *perr_elem)
709 {
710 	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
711 	struct mesh_path *mpath;
712 	u8 ttl;
713 	u8 *ta, *target_addr;
714 	u32 target_sn;
715 	u16 target_rcode;
716 
717 	ta = mgmt->sa;
718 	ttl = PERR_IE_TTL(perr_elem);
719 	if (ttl <= 1) {
720 		ifmsh->mshstats.dropped_frames_ttl++;
721 		return;
722 	}
723 	ttl--;
724 	target_addr = PERR_IE_TARGET_ADDR(perr_elem);
725 	target_sn = PERR_IE_TARGET_SN(perr_elem);
726 	target_rcode = PERR_IE_TARGET_RCODE(perr_elem);
727 
728 	rcu_read_lock();
729 	mpath = mesh_path_lookup(target_addr, sdata);
730 	if (mpath) {
731 		struct sta_info *sta;
732 
733 		spin_lock_bh(&mpath->state_lock);
734 		sta = next_hop_deref_protected(mpath);
735 		if (mpath->flags & MESH_PATH_ACTIVE &&
736 		    ether_addr_equal(ta, sta->sta.addr) &&
737 		    (!(mpath->flags & MESH_PATH_SN_VALID) ||
738 		    SN_GT(target_sn, mpath->sn))) {
739 			mpath->flags &= ~MESH_PATH_ACTIVE;
740 			mpath->sn = target_sn;
741 			spin_unlock_bh(&mpath->state_lock);
742 			if (!ifmsh->mshcfg.dot11MeshForwarding)
743 				goto endperr;
744 			mesh_path_error_tx(ttl, target_addr, cpu_to_le32(target_sn),
745 					   cpu_to_le16(target_rcode),
746 					   broadcast_addr, sdata);
747 		} else
748 			spin_unlock_bh(&mpath->state_lock);
749 	}
750 endperr:
751 	rcu_read_unlock();
752 }
753 
754 static void hwmp_rann_frame_process(struct ieee80211_sub_if_data *sdata,
755 				struct ieee80211_mgmt *mgmt,
756 				struct ieee80211_rann_ie *rann)
757 {
758 	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
759 	struct ieee80211_local *local = sdata->local;
760 	struct sta_info *sta;
761 	struct mesh_path *mpath;
762 	u8 ttl, flags, hopcount;
763 	u8 *orig_addr;
764 	u32 orig_sn, metric, metric_txsta, interval;
765 	bool root_is_gate;
766 
767 	ttl = rann->rann_ttl;
768 	flags = rann->rann_flags;
769 	root_is_gate = !!(flags & RANN_FLAG_IS_GATE);
770 	orig_addr = rann->rann_addr;
771 	orig_sn = le32_to_cpu(rann->rann_seq);
772 	interval = le32_to_cpu(rann->rann_interval);
773 	hopcount = rann->rann_hopcount;
774 	hopcount++;
775 	metric = le32_to_cpu(rann->rann_metric);
776 
777 	/*  Ignore our own RANNs */
778 	if (ether_addr_equal(orig_addr, sdata->vif.addr))
779 		return;
780 
781 	mhwmp_dbg(sdata,
782 		  "received RANN from %pM via neighbour %pM (is_gate=%d)\n",
783 		  orig_addr, mgmt->sa, root_is_gate);
784 
785 	rcu_read_lock();
786 	sta = sta_info_get(sdata, mgmt->sa);
787 	if (!sta) {
788 		rcu_read_unlock();
789 		return;
790 	}
791 
792 	metric_txsta = airtime_link_metric_get(local, sta);
793 
794 	mpath = mesh_path_lookup(orig_addr, sdata);
795 	if (!mpath) {
796 		mesh_path_add(orig_addr, sdata);
797 		mpath = mesh_path_lookup(orig_addr, sdata);
798 		if (!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 				       cpu_to_le32(orig_sn),
843 				       0, NULL, 0, broadcast_addr,
844 				       hopcount, ttl, cpu_to_le32(interval),
845 				       cpu_to_le32(metric + metric_txsta),
846 				       0, sdata);
847 	}
848 
849 	rcu_read_unlock();
850 }
851 
852 
853 void mesh_rx_path_sel_frame(struct ieee80211_sub_if_data *sdata,
854 			    struct ieee80211_mgmt *mgmt,
855 			    size_t len)
856 {
857 	struct ieee802_11_elems elems;
858 	size_t baselen;
859 	u32 last_hop_metric;
860 	struct sta_info *sta;
861 
862 	/* need action_code */
863 	if (len < IEEE80211_MIN_ACTION_SIZE + 1)
864 		return;
865 
866 	rcu_read_lock();
867 	sta = sta_info_get(sdata, mgmt->sa);
868 	if (!sta || sta->plink_state != NL80211_PLINK_ESTAB) {
869 		rcu_read_unlock();
870 		return;
871 	}
872 	rcu_read_unlock();
873 
874 	baselen = (u8 *) mgmt->u.action.u.mesh_action.variable - (u8 *) mgmt;
875 	ieee802_11_parse_elems(mgmt->u.action.u.mesh_action.variable,
876 			len - baselen, &elems);
877 
878 	if (elems.preq) {
879 		if (elems.preq_len != 37)
880 			/* Right now we support just 1 destination and no AE */
881 			return;
882 		last_hop_metric = hwmp_route_info_get(sdata, mgmt, elems.preq,
883 						      MPATH_PREQ);
884 		if (last_hop_metric)
885 			hwmp_preq_frame_process(sdata, mgmt, elems.preq,
886 						last_hop_metric);
887 	}
888 	if (elems.prep) {
889 		if (elems.prep_len != 31)
890 			/* Right now we support no AE */
891 			return;
892 		last_hop_metric = hwmp_route_info_get(sdata, mgmt, elems.prep,
893 						      MPATH_PREP);
894 		if (last_hop_metric)
895 			hwmp_prep_frame_process(sdata, mgmt, elems.prep,
896 						last_hop_metric);
897 	}
898 	if (elems.perr) {
899 		if (elems.perr_len != 15)
900 			/* Right now we support only one destination per PERR */
901 			return;
902 		hwmp_perr_frame_process(sdata, mgmt, elems.perr);
903 	}
904 	if (elems.rann)
905 		hwmp_rann_frame_process(sdata, mgmt, elems.rann);
906 }
907 
908 /**
909  * mesh_queue_preq - queue a PREQ to a given destination
910  *
911  * @mpath: mesh path to discover
912  * @flags: special attributes of the PREQ to be sent
913  *
914  * Locking: the function must be called from within a rcu read lock block.
915  *
916  */
917 static void mesh_queue_preq(struct mesh_path *mpath, u8 flags)
918 {
919 	struct ieee80211_sub_if_data *sdata = mpath->sdata;
920 	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
921 	struct mesh_preq_queue *preq_node;
922 
923 	preq_node = kmalloc(sizeof(struct mesh_preq_queue), GFP_ATOMIC);
924 	if (!preq_node) {
925 		mhwmp_dbg(sdata, "could not allocate PREQ node\n");
926 		return;
927 	}
928 
929 	spin_lock_bh(&ifmsh->mesh_preq_queue_lock);
930 	if (ifmsh->preq_queue_len == MAX_PREQ_QUEUE_LEN) {
931 		spin_unlock_bh(&ifmsh->mesh_preq_queue_lock);
932 		kfree(preq_node);
933 		if (printk_ratelimit())
934 			mhwmp_dbg(sdata, "PREQ node queue full\n");
935 		return;
936 	}
937 
938 	spin_lock(&mpath->state_lock);
939 	if (mpath->flags & MESH_PATH_REQ_QUEUED) {
940 		spin_unlock(&mpath->state_lock);
941 		spin_unlock_bh(&ifmsh->mesh_preq_queue_lock);
942 		kfree(preq_node);
943 		return;
944 	}
945 
946 	memcpy(preq_node->dst, mpath->dst, ETH_ALEN);
947 	preq_node->flags = flags;
948 
949 	mpath->flags |= MESH_PATH_REQ_QUEUED;
950 	spin_unlock(&mpath->state_lock);
951 
952 	list_add_tail(&preq_node->list, &ifmsh->preq_queue.list);
953 	++ifmsh->preq_queue_len;
954 	spin_unlock_bh(&ifmsh->mesh_preq_queue_lock);
955 
956 	if (time_after(jiffies, ifmsh->last_preq + min_preq_int_jiff(sdata)))
957 		ieee80211_queue_work(&sdata->local->hw, &sdata->work);
958 
959 	else if (time_before(jiffies, ifmsh->last_preq)) {
960 		/* avoid long wait if did not send preqs for a long time
961 		 * and jiffies wrapped around
962 		 */
963 		ifmsh->last_preq = jiffies - min_preq_int_jiff(sdata) - 1;
964 		ieee80211_queue_work(&sdata->local->hw, &sdata->work);
965 	} else
966 		mod_timer(&ifmsh->mesh_path_timer, ifmsh->last_preq +
967 						min_preq_int_jiff(sdata));
968 }
969 
970 /**
971  * mesh_path_start_discovery - launch a path discovery from the PREQ queue
972  *
973  * @sdata: local mesh subif
974  */
975 void mesh_path_start_discovery(struct ieee80211_sub_if_data *sdata)
976 {
977 	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
978 	struct mesh_preq_queue *preq_node;
979 	struct mesh_path *mpath;
980 	u8 ttl, target_flags;
981 	const u8 *da;
982 	u32 lifetime;
983 
984 	spin_lock_bh(&ifmsh->mesh_preq_queue_lock);
985 	if (!ifmsh->preq_queue_len ||
986 		time_before(jiffies, ifmsh->last_preq +
987 				min_preq_int_jiff(sdata))) {
988 		spin_unlock_bh(&ifmsh->mesh_preq_queue_lock);
989 		return;
990 	}
991 
992 	preq_node = list_first_entry(&ifmsh->preq_queue.list,
993 			struct mesh_preq_queue, list);
994 	list_del(&preq_node->list);
995 	--ifmsh->preq_queue_len;
996 	spin_unlock_bh(&ifmsh->mesh_preq_queue_lock);
997 
998 	rcu_read_lock();
999 	mpath = mesh_path_lookup(preq_node->dst, sdata);
1000 	if (!mpath)
1001 		goto enddiscovery;
1002 
1003 	spin_lock_bh(&mpath->state_lock);
1004 	mpath->flags &= ~MESH_PATH_REQ_QUEUED;
1005 	if (preq_node->flags & PREQ_Q_F_START) {
1006 		if (mpath->flags & MESH_PATH_RESOLVING) {
1007 			spin_unlock_bh(&mpath->state_lock);
1008 			goto enddiscovery;
1009 		} else {
1010 			mpath->flags &= ~MESH_PATH_RESOLVED;
1011 			mpath->flags |= MESH_PATH_RESOLVING;
1012 			mpath->discovery_retries = 0;
1013 			mpath->discovery_timeout = disc_timeout_jiff(sdata);
1014 		}
1015 	} else if (!(mpath->flags & MESH_PATH_RESOLVING) ||
1016 			mpath->flags & MESH_PATH_RESOLVED) {
1017 		mpath->flags &= ~MESH_PATH_RESOLVING;
1018 		spin_unlock_bh(&mpath->state_lock);
1019 		goto enddiscovery;
1020 	}
1021 
1022 	ifmsh->last_preq = jiffies;
1023 
1024 	if (time_after(jiffies, ifmsh->last_sn_update +
1025 				net_traversal_jiffies(sdata)) ||
1026 	    time_before(jiffies, ifmsh->last_sn_update)) {
1027 		++ifmsh->sn;
1028 		sdata->u.mesh.last_sn_update = jiffies;
1029 	}
1030 	lifetime = default_lifetime(sdata);
1031 	ttl = sdata->u.mesh.mshcfg.element_ttl;
1032 	if (ttl == 0) {
1033 		sdata->u.mesh.mshstats.dropped_frames_ttl++;
1034 		spin_unlock_bh(&mpath->state_lock);
1035 		goto enddiscovery;
1036 	}
1037 
1038 	if (preq_node->flags & PREQ_Q_F_REFRESH)
1039 		target_flags = MP_F_DO;
1040 	else
1041 		target_flags = MP_F_RF;
1042 
1043 	spin_unlock_bh(&mpath->state_lock);
1044 	da = (mpath->is_root) ? mpath->rann_snd_addr : broadcast_addr;
1045 	mesh_path_sel_frame_tx(MPATH_PREQ, 0, sdata->vif.addr,
1046 			cpu_to_le32(ifmsh->sn), target_flags, mpath->dst,
1047 			cpu_to_le32(mpath->sn), da, 0,
1048 			ttl, cpu_to_le32(lifetime), 0,
1049 			cpu_to_le32(ifmsh->preq_id++), sdata);
1050 	mod_timer(&mpath->timer, jiffies + mpath->discovery_timeout);
1051 
1052 enddiscovery:
1053 	rcu_read_unlock();
1054 	kfree(preq_node);
1055 }
1056 
1057 /**
1058  * mesh_nexthop_resolve - lookup next hop; conditionally start path discovery
1059  *
1060  * @skb: 802.11 frame to be sent
1061  * @sdata: network subif the frame will be sent through
1062  *
1063  * Lookup next hop for given skb and start path discovery if no
1064  * forwarding information is found.
1065  *
1066  * Returns: 0 if the next hop was found and -ENOENT if the frame was queued.
1067  * skb is freeed here if no mpath could be allocated.
1068  */
1069 int mesh_nexthop_resolve(struct sk_buff *skb,
1070 			 struct ieee80211_sub_if_data *sdata)
1071 {
1072 	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
1073 	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
1074 	struct mesh_path *mpath;
1075 	struct sk_buff *skb_to_free = NULL;
1076 	u8 *target_addr = hdr->addr3;
1077 	int err = 0;
1078 
1079 	rcu_read_lock();
1080 	err = mesh_nexthop_lookup(skb, sdata);
1081 	if (!err)
1082 		goto endlookup;
1083 
1084 	/* no nexthop found, start resolving */
1085 	mpath = mesh_path_lookup(target_addr, sdata);
1086 	if (!mpath) {
1087 		mesh_path_add(target_addr, sdata);
1088 		mpath = mesh_path_lookup(target_addr, sdata);
1089 		if (!mpath) {
1090 			mesh_path_discard_frame(skb, sdata);
1091 			err = -ENOSPC;
1092 			goto endlookup;
1093 		}
1094 	}
1095 
1096 	if (!(mpath->flags & MESH_PATH_RESOLVING))
1097 		mesh_queue_preq(mpath, PREQ_Q_F_START);
1098 
1099 	if (skb_queue_len(&mpath->frame_queue) >= MESH_FRAME_QUEUE_LEN)
1100 		skb_to_free = skb_dequeue(&mpath->frame_queue);
1101 
1102 	info->flags |= IEEE80211_TX_INTFL_NEED_TXPROCESSING;
1103 	ieee80211_set_qos_hdr(sdata, skb);
1104 	skb_queue_tail(&mpath->frame_queue, skb);
1105 	err = -ENOENT;
1106 	if (skb_to_free)
1107 		mesh_path_discard_frame(skb_to_free, sdata);
1108 
1109 endlookup:
1110 	rcu_read_unlock();
1111 	return err;
1112 }
1113 /**
1114  * mesh_nexthop_lookup - put the appropriate next hop on a mesh frame. Calling
1115  * this function is considered "using" the associated mpath, so preempt a path
1116  * refresh if this mpath expires soon.
1117  *
1118  * @skb: 802.11 frame to be sent
1119  * @sdata: network subif the frame will be sent through
1120  *
1121  * Returns: 0 if the next hop was found. Nonzero otherwise.
1122  */
1123 int mesh_nexthop_lookup(struct sk_buff *skb,
1124 			struct ieee80211_sub_if_data *sdata)
1125 {
1126 	struct mesh_path *mpath;
1127 	struct sta_info *next_hop;
1128 	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
1129 	u8 *target_addr = hdr->addr3;
1130 	int err = -ENOENT;
1131 
1132 	rcu_read_lock();
1133 	mpath = mesh_path_lookup(target_addr, sdata);
1134 
1135 	if (!mpath || !(mpath->flags & MESH_PATH_ACTIVE))
1136 		goto endlookup;
1137 
1138 	if (time_after(jiffies,
1139 		       mpath->exp_time -
1140 		       msecs_to_jiffies(sdata->u.mesh.mshcfg.path_refresh_time)) &&
1141 	    ether_addr_equal(sdata->vif.addr, hdr->addr4) &&
1142 	    !(mpath->flags & MESH_PATH_RESOLVING) &&
1143 	    !(mpath->flags & MESH_PATH_FIXED))
1144 		mesh_queue_preq(mpath, PREQ_Q_F_START | PREQ_Q_F_REFRESH);
1145 
1146 	next_hop = rcu_dereference(mpath->next_hop);
1147 	if (next_hop) {
1148 		memcpy(hdr->addr1, next_hop->sta.addr, ETH_ALEN);
1149 		memcpy(hdr->addr2, sdata->vif.addr, ETH_ALEN);
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
1192 mesh_path_tx_root_frame(struct ieee80211_sub_if_data *sdata)
1193 {
1194 	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
1195 	u32 interval = ifmsh->mshcfg.dot11MeshHWMPRannInterval;
1196 	u8 flags, target_flags = 0;
1197 
1198 	flags = (ifmsh->mshcfg.dot11MeshGateAnnouncementProtocol)
1199 			? RANN_FLAG_IS_GATE : 0;
1200 
1201 	switch (ifmsh->mshcfg.dot11MeshHWMPRootMode) {
1202 	case IEEE80211_PROACTIVE_RANN:
1203 		mesh_path_sel_frame_tx(MPATH_RANN, flags, sdata->vif.addr,
1204 			       cpu_to_le32(++ifmsh->sn),
1205 			       0, NULL, 0, broadcast_addr,
1206 			       0, ifmsh->mshcfg.element_ttl,
1207 			       cpu_to_le32(interval), 0, 0, sdata);
1208 		break;
1209 	case IEEE80211_PROACTIVE_PREQ_WITH_PREP:
1210 		flags |= IEEE80211_PREQ_PROACTIVE_PREP_FLAG;
1211 	case IEEE80211_PROACTIVE_PREQ_NO_PREP:
1212 		interval = ifmsh->mshcfg.dot11MeshHWMPactivePathToRootTimeout;
1213 		target_flags |= IEEE80211_PREQ_TO_FLAG |
1214 				IEEE80211_PREQ_USN_FLAG;
1215 		mesh_path_sel_frame_tx(MPATH_PREQ, flags, sdata->vif.addr,
1216 				cpu_to_le32(++ifmsh->sn), target_flags,
1217 				(u8 *) broadcast_addr, 0, broadcast_addr,
1218 				0, ifmsh->mshcfg.element_ttl,
1219 				cpu_to_le32(interval),
1220 				0, cpu_to_le32(ifmsh->preq_id++), sdata);
1221 		break;
1222 	default:
1223 		mhwmp_dbg(sdata, "Proactive mechanism not supported\n");
1224 		return;
1225 	}
1226 }
1227