text: /*
   * Copyright (c) 2008, 2009 open80211s Ltd.
   * Author:     Luis Carlos Cobo <luisca@cozybit.com>
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License version 2 as
   * published by the Free Software Foundation.
   */
  
  #include <linux/slab.h>
  #include <linux/etherdevice.h>
  #include <asm/unaligned.h>
  #include "wme.h"
  #include "mesh.h"
  
  #define TEST_FRAME_LEN	8192
  #define MAX_METRIC	0xffffffff
  #define ARITH_SHIFT	8
  #define LINK_FAIL_THRESH 95
  
  #define MAX_PREQ_QUEUE_LEN	64
  
  static void mesh_queue_preq(struct mesh_path *, u8);
  
  static inline u32 u32_field_get(const u8 *preq_elem, int offset, bool ae)
  {
  	if (ae)
  		offset += 6;
  	return get_unaligned_le32(preq_elem + offset);
  }
  
  static inline u16 u16_field_get(const u8 *preq_elem, int offset, bool ae)
  {
  	if (ae)
  		offset += 6;
  	return get_unaligned_le16(preq_elem + offset);
  }
  
  /* HWMP IE processing macros */
  #define AE_F			(1<<6)
  #define AE_F_SET(x)		(*x & AE_F)
  #define PREQ_IE_FLAGS(x)	(*(x))
  #define PREQ_IE_HOPCOUNT(x)	(*(x + 1))
  #define PREQ_IE_TTL(x)		(*(x + 2))
  #define PREQ_IE_PREQ_ID(x)	u32_field_get(x, 3, 0)
  #define PREQ_IE_ORIG_ADDR(x)	(x + 7)
  #define PREQ_IE_ORIG_SN(x)	u32_field_get(x, 13, 0)
  #define PREQ_IE_LIFETIME(x)	u32_field_get(x, 17, AE_F_SET(x))
  #define PREQ_IE_METRIC(x) 	u32_field_get(x, 21, AE_F_SET(x))
  #define PREQ_IE_TARGET_F(x)	(*(AE_F_SET(x) ? x + 32 : x + 26))
  #define PREQ_IE_TARGET_ADDR(x) 	(AE_F_SET(x) ? x + 33 : x + 27)
  #define PREQ_IE_TARGET_SN(x) 	u32_field_get(x, 33, AE_F_SET(x))
  
  
  #define PREP_IE_FLAGS(x)	PREQ_IE_FLAGS(x)
  #define PREP_IE_HOPCOUNT(x)	PREQ_IE_HOPCOUNT(x)
  #define PREP_IE_TTL(x)		PREQ_IE_TTL(x)
  #define PREP_IE_ORIG_ADDR(x)	(AE_F_SET(x) ? x + 27 : x + 21)
  #define PREP_IE_ORIG_SN(x)	u32_field_get(x, 27, AE_F_SET(x))
  #define PREP_IE_LIFETIME(x)	u32_field_get(x, 13, AE_F_SET(x))
  #define PREP_IE_METRIC(x)	u32_field_get(x, 17, AE_F_SET(x))
  #define PREP_IE_TARGET_ADDR(x)	(x + 3)
  #define PREP_IE_TARGET_SN(x)	u32_field_get(x, 9, 0)
  
  #define PERR_IE_TTL(x)		(*(x))
  #define PERR_IE_TARGET_FLAGS(x)	(*(x + 2))
  #define PERR_IE_TARGET_ADDR(x)	(x + 3)
  #define PERR_IE_TARGET_SN(x)	u32_field_get(x, 9, 0)
  #define PERR_IE_TARGET_RCODE(x)	u16_field_get(x, 13, 0)
  
  #define MSEC_TO_TU(x) (x*1000/1024)
  #define SN_GT(x, y) ((s32)(y - x) < 0)
  #define SN_LT(x, y) ((s32)(x - y) < 0)
  #define MAX_SANE_SN_DELTA 32
  
  static inline u32 SN_DELTA(u32 x, u32 y)
  {
  	return x >= y ? x - y : y - x;
  }
  
  #define net_traversal_jiffies(s) \
  	msecs_to_jiffies(s->u.mesh.mshcfg.dot11MeshHWMPnetDiameterTraversalTime)
  #define default_lifetime(s) \
  	MSEC_TO_TU(s->u.mesh.mshcfg.dot11MeshHWMPactivePathTimeout)
  #define min_preq_int_jiff(s) \
  	(msecs_to_jiffies(s->u.mesh.mshcfg.dot11MeshHWMPpreqMinInterval))
  #define max_preq_retries(s) (s->u.mesh.mshcfg.dot11MeshHWMPmaxPREQretries)
  #define disc_timeout_jiff(s) \
  	msecs_to_jiffies(sdata->u.mesh.mshcfg.min_discovery_timeout)
  #define root_path_confirmation_jiffies(s) \
  	msecs_to_jiffies(sdata->u.mesh.mshcfg.dot11MeshHWMPconfirmationInterval)
  
  enum mpath_frame_type {
  	MPATH_PREQ = 0,
  	MPATH_PREP,
  	MPATH_PERR,
  	MPATH_RANN
  };
  
  static const u8 broadcast_addr[ETH_ALEN] = {0xff, 0xff, 0xff, 0xff, 0xff, 0xff};
  
  static int mesh_path_sel_frame_tx(enum mpath_frame_type action, u8 flags,
  				  const u8 *orig_addr, u32 orig_sn,
  				  u8 target_flags, const u8 *target,
  				  u32 target_sn, const u8 *da,
  				  u8 hop_count, u8 ttl,
  				  u32 lifetime, u32 metric, u32 preq_id,
  				  struct ieee80211_sub_if_data *sdata)
  {
  	struct ieee80211_local *local = sdata->local;
  	struct sk_buff *skb;
  	struct ieee80211_mgmt *mgmt;
  	u8 *pos, ie_len;
  	int hdr_len = offsetofend(struct ieee80211_mgmt,
  				  u.action.u.mesh_action);
  
  	skb = dev_alloc_skb(local->tx_headroom +
  			    hdr_len +
  			    2 + 37); /* max HWMP IE */
  	if (!skb)
  		return -1;
  	skb_reserve(skb, local->tx_headroom);
  	mgmt = skb_put_zero(skb, hdr_len);
  	mgmt->frame_control = cpu_to_le16(IEEE80211_FTYPE_MGMT |
  					  IEEE80211_STYPE_ACTION);
  
  	memcpy(mgmt->da, da, ETH_ALEN);
  	memcpy(mgmt->sa, sdata->vif.addr, ETH_ALEN);
  	/* BSSID == SA */
  	memcpy(mgmt->bssid, sdata->vif.addr, ETH_ALEN);
  	mgmt->u.action.category = WLAN_CATEGORY_MESH_ACTION;
  	mgmt->u.action.u.mesh_action.action_code =
  					WLAN_MESH_ACTION_HWMP_PATH_SELECTION;
  
  	switch (action) {
  	case MPATH_PREQ:
  		mhwmp_dbg(sdata, "sending PREQ to %pM\n", target);
  		ie_len = 37;
  		pos = skb_put(skb, 2 + ie_len);
  		*pos++ = WLAN_EID_PREQ;
  		break;
  	case MPATH_PREP:
  		mhwmp_dbg(sdata, "sending PREP to %pM\n", orig_addr);
  		ie_len = 31;
  		pos = skb_put(skb, 2 + ie_len);
  		*pos++ = WLAN_EID_PREP;
  		break;
  	case MPATH_RANN:
  		mhwmp_dbg(sdata, "sending RANN from %pM\n", orig_addr);
  		ie_len = sizeof(struct ieee80211_rann_ie);
  		pos = skb_put(skb, 2 + ie_len);
  		*pos++ = WLAN_EID_RANN;
  		break;
  	default:
  		kfree_skb(skb);
  		return -ENOTSUPP;
  	}
  	*pos++ = ie_len;
  	*pos++ = flags;
  	*pos++ = hop_count;
  	*pos++ = ttl;
  	if (action == MPATH_PREP) {
  		memcpy(pos, target, ETH_ALEN);
  		pos += ETH_ALEN;
  		put_unaligned_le32(target_sn, pos);
  		pos += 4;
  	} else {
  		if (action == MPATH_PREQ) {
  			put_unaligned_le32(preq_id, pos);
  			pos += 4;
  		}
  		memcpy(pos, orig_addr, ETH_ALEN);
  		pos += ETH_ALEN;
  		put_unaligned_le32(orig_sn, pos);
  		pos += 4;
  	}
  	put_unaligned_le32(lifetime, pos); /* interval for RANN */
  	pos += 4;
  	put_unaligned_le32(metric, pos);
  	pos += 4;
  	if (action == MPATH_PREQ) {
  		*pos++ = 1; /* destination count */
  		*pos++ = target_flags;
  		memcpy(pos, target, ETH_ALEN);
  		pos += ETH_ALEN;
  		put_unaligned_le32(target_sn, pos);
  		pos += 4;
  	} else if (action == MPATH_PREP) {
  		memcpy(pos, orig_addr, ETH_ALEN);
  		pos += ETH_ALEN;
  		put_unaligned_le32(orig_sn, pos);
  		pos += 4;
  	}
  
  	ieee80211_tx_skb(sdata, skb);
  	return 0;
  }
  
  
  /*  Headroom is not adjusted.  Caller should ensure that skb has sufficient
   *  headroom in case the frame is encrypted. */
  static void prepare_frame_for_deferred_tx(struct ieee80211_sub_if_data *sdata,
  		struct sk_buff *skb)
  {
  	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
  	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
  
  	skb_reset_mac_header(skb);
  	skb_reset_network_header(skb);
  	skb_reset_transport_header(skb);
  
  	/* Send all internal mgmt frames on VO. Accordingly set TID to 7. */
  	skb_set_queue_mapping(skb, IEEE80211_AC_VO);
  	skb->priority = 7;
  
  	info->control.vif = &sdata->vif;
  	info->flags |= IEEE80211_TX_INTFL_NEED_TXPROCESSING;
  	ieee80211_set_qos_hdr(sdata, skb);
  	ieee80211_mps_set_frame_flags(sdata, NULL, hdr);
  }
  
  /**
   * mesh_path_error_tx - Sends a PERR mesh management frame
   *
   * @ttl: allowed remaining hops
   * @target: broken destination
   * @target_sn: SN of the broken destination
   * @target_rcode: reason code for this PERR
   * @ra: node this frame is addressed to
   * @sdata: local mesh subif
   *
   * Note: This function may be called with driver locks taken that the driver
   * also acquires in the TX path.  To avoid a deadlock we don't transmit the
   * frame directly but add it to the pending queue instead.
   */
  int mesh_path_error_tx(struct ieee80211_sub_if_data *sdata,
  		       u8 ttl, const u8 *target, u32 target_sn,
  		       u16 target_rcode, const u8 *ra)
  {
  	struct ieee80211_local *local = sdata->local;
  	struct sk_buff *skb;
  	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
  	struct ieee80211_mgmt *mgmt;
  	u8 *pos, ie_len;
  	int hdr_len = offsetofend(struct ieee80211_mgmt,
  				  u.action.u.mesh_action);
  
  	if (time_before(jiffies, ifmsh->next_perr))
  		return -EAGAIN;
  
  	skb = dev_alloc_skb(local->tx_headroom +
  			    sdata->encrypt_headroom +
  			    IEEE80211_ENCRYPT_TAILROOM +
  			    hdr_len +
  			    2 + 15 /* PERR IE */);
  	if (!skb)
  		return -1;
  	skb_reserve(skb, local->tx_headroom + sdata->encrypt_headroom);
  	mgmt = skb_put_zero(skb, hdr_len);
  	mgmt->frame_control = cpu_to_le16(IEEE80211_FTYPE_MGMT |
  					  IEEE80211_STYPE_ACTION);
  
  	memcpy(mgmt->da, ra, ETH_ALEN);
  	memcpy(mgmt->sa, sdata->vif.addr, ETH_ALEN);
  	/* BSSID == SA */
  	memcpy(mgmt->bssid, sdata->vif.addr, ETH_ALEN);
  	mgmt->u.action.category = WLAN_CATEGORY_MESH_ACTION;
  	mgmt->u.action.u.mesh_action.action_code =
  					WLAN_MESH_ACTION_HWMP_PATH_SELECTION;
  	ie_len = 15;
  	pos = skb_put(skb, 2 + ie_len);
  	*pos++ = WLAN_EID_PERR;
  	*pos++ = ie_len;
  	/* ttl */
  	*pos++ = ttl;
  	/* number of destinations */
  	*pos++ = 1;
  	/* Flags field has AE bit only as defined in
  	 * sec 8.4.2.117 IEEE802.11-2012
  	 */
  	*pos = 0;
  	pos++;
  	memcpy(pos, target, ETH_ALEN);
  	pos += ETH_ALEN;
  	put_unaligned_le32(target_sn, pos);
  	pos += 4;
  	put_unaligned_le16(target_rcode, pos);
  
  	/* see note in function header */
  	prepare_frame_for_deferred_tx(sdata, skb);
  	ifmsh->next_perr = TU_TO_EXP_TIME(
  				   ifmsh->mshcfg.dot11MeshHWMPperrMinInterval);
  	ieee80211_add_pending_skb(local, skb);
  	return 0;
  }
  
  void ieee80211s_update_metric(struct ieee80211_local *local,
  		struct sta_info *sta, struct sk_buff *skb)
  {
  	struct ieee80211_tx_info *txinfo = IEEE80211_SKB_CB(skb);
  	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
  	int failed;
  
  	if (!ieee80211_is_data(hdr->frame_control))
  		return;
  
  	failed = !(txinfo->flags & IEEE80211_TX_STAT_ACK);
  
  	/* moving average, scaled to 100.
  	 * feed failure as 100 and success as 0
  	 */
  	ewma_mesh_fail_avg_add(&sta->mesh->fail_avg, failed * 100);
  	if (ewma_mesh_fail_avg_read(&sta->mesh->fail_avg) >
  			LINK_FAIL_THRESH)
  		mesh_plink_broken(sta);
  }
  
  static u32 airtime_link_metric_get(struct ieee80211_local *local,
  				   struct sta_info *sta)
  {
  	struct rate_info rinfo;
  	/* This should be adjusted for each device */
  	int device_constant = 1 << ARITH_SHIFT;
  	int test_frame_len = TEST_FRAME_LEN << ARITH_SHIFT;
  	int s_unit = 1 << ARITH_SHIFT;
  	int rate, err;
  	u32 tx_time, estimated_retx;
  	u64 result;
  	unsigned long fail_avg =
  		ewma_mesh_fail_avg_read(&sta->mesh->fail_avg);
  
  	/* Try to get rate based on HW/SW RC algorithm.
  	 * Rate is returned in units of Kbps, correct this
  	 * to comply with airtime calculation units
  	 * Round up in case we get rate < 100Kbps
  	 */
  	rate = DIV_ROUND_UP(sta_get_expected_throughput(sta), 100);
  
  	if (rate) {
  		err = 0;
  	} else {
  		if (fail_avg > LINK_FAIL_THRESH)
  			return MAX_METRIC;
  
  		sta_set_rate_info_tx(sta, &sta->tx_stats.last_rate, &rinfo);
  		rate = cfg80211_calculate_bitrate(&rinfo);
  		if (WARN_ON(!rate))
  			return MAX_METRIC;
  
  		err = (fail_avg << ARITH_SHIFT) / 100;
  	}
  
  	/* bitrate is in units of 100 Kbps, while we need rate in units of
  	 * 1Mbps. This will be corrected on tx_time computation.
  	 */
  	tx_time = (device_constant + 10 * test_frame_len / rate);
  	estimated_retx = ((1 << (2 * ARITH_SHIFT)) / (s_unit - err));
  	result = (tx_time * estimated_retx) >> (2 * ARITH_SHIFT);
  	return (u32)result;
  }
  
  /**
   * hwmp_route_info_get - Update routing info to originator and transmitter
   *
   * @sdata: local mesh subif
   * @mgmt: mesh management frame
   * @hwmp_ie: hwmp information element (PREP or PREQ)
   * @action: type of hwmp ie
   *
   * This function updates the path routing information to the originator and the
   * transmitter of a HWMP PREQ or PREP frame.
   *
   * Returns: metric to frame originator or 0 if the frame should not be further
   * processed
   *
   * Notes: this function is the only place (besides user-provided info) where
   * path routing information is updated.
   */
  static u32 hwmp_route_info_get(struct ieee80211_sub_if_data *sdata,
  			       struct ieee80211_mgmt *mgmt,
  			       const u8 *hwmp_ie, enum mpath_frame_type action)
  {
  	struct ieee80211_local *local = sdata->local;
  	struct mesh_path *mpath;
  	struct sta_info *sta;
  	bool fresh_info;
  	const u8 *orig_addr, *ta;
  	u32 orig_sn, orig_metric;
  	unsigned long orig_lifetime, exp_time;
  	u32 last_hop_metric, new_metric;
  	bool process = true;
  
  	rcu_read_lock();
  	sta = sta_info_get(sdata, mgmt->sa);
  	if (!sta) {
  		rcu_read_unlock();
  		return 0;
  	}
  
  	last_hop_metric = airtime_link_metric_get(local, sta);
  	/* Update and check originator routing info */
  	fresh_info = true;
  
  	switch (action) {
  	case MPATH_PREQ:
  		orig_addr = PREQ_IE_ORIG_ADDR(hwmp_ie);
  		orig_sn = PREQ_IE_ORIG_SN(hwmp_ie);
  		orig_lifetime = PREQ_IE_LIFETIME(hwmp_ie);
  		orig_metric = PREQ_IE_METRIC(hwmp_ie);
  		break;
  	case MPATH_PREP:
  		/* Originator here refers to the MP that was the target in the
  		 * Path Request. We divert from the nomenclature in the draft
  		 * so that we can easily use a single function to gather path
  		 * information from both PREQ and PREP frames.
  		 */
  		orig_addr = PREP_IE_TARGET_ADDR(hwmp_ie);
  		orig_sn = PREP_IE_TARGET_SN(hwmp_ie);
  		orig_lifetime = PREP_IE_LIFETIME(hwmp_ie);
  		orig_metric = PREP_IE_METRIC(hwmp_ie);
  		break;
  	default:
  		rcu_read_unlock();
  		return 0;
  	}
  	new_metric = orig_metric + last_hop_metric;
  	if (new_metric < orig_metric)
  		new_metric = MAX_METRIC;
  	exp_time = TU_TO_EXP_TIME(orig_lifetime);
  
  	if (ether_addr_equal(orig_addr, sdata->vif.addr)) {
  		/* This MP is the originator, we are not interested in this
  		 * frame, except for updating transmitter's path info.
  		 */
  		process = false;
  		fresh_info = false;
  	} else {
  		mpath = mesh_path_lookup(sdata, orig_addr);
  		if (mpath) {
  			spin_lock_bh(&mpath->state_lock);
  			if (mpath->flags & MESH_PATH_FIXED)
  				fresh_info = false;
  			else if ((mpath->flags & MESH_PATH_ACTIVE) &&
  			    (mpath->flags & MESH_PATH_SN_VALID)) {
  				if (SN_GT(mpath->sn, orig_sn) ||
  				    (mpath->sn == orig_sn &&
  				     new_metric >= mpath->metric)) {
  					process = false;
  					fresh_info = false;
  				}
  			} else if (!(mpath->flags & MESH_PATH_ACTIVE)) {
  				bool have_sn, newer_sn, bounced;
  
  				have_sn = mpath->flags & MESH_PATH_SN_VALID;
  				newer_sn = have_sn && SN_GT(orig_sn, mpath->sn);
  				bounced = have_sn &&
  					  (SN_DELTA(orig_sn, mpath->sn) >
  							MAX_SANE_SN_DELTA);
  
  				if (!have_sn || newer_sn) {
  					/* if SN is newer than what we had
  					 * then we can take it */;
  				} else if (bounced) {
  					/* if SN is way different than what
  					 * we had then assume the other side
  					 * rebooted or restarted */;
  				} else {
  					process = false;
  					fresh_info = false;
  				}
  			}
  		} else {
  			mpath = mesh_path_add(sdata, orig_addr);
  			if (IS_ERR(mpath)) {
  				rcu_read_unlock();
  				return 0;
  			}
  			spin_lock_bh(&mpath->state_lock);
  		}
  
  		if (fresh_info) {
  			mesh_path_assign_nexthop(mpath, sta);
  			mpath->flags |= MESH_PATH_SN_VALID;
  			mpath->metric = new_metric;
  			mpath->sn = orig_sn;
  			mpath->exp_time = time_after(mpath->exp_time, exp_time)
  					  ?  mpath->exp_time : exp_time;
  			mesh_path_activate(mpath);
  			spin_unlock_bh(&mpath->state_lock);
  			ewma_mesh_fail_avg_init(&sta->mesh->fail_avg);
  			/* init it at a low value - 0 start is tricky */
  			ewma_mesh_fail_avg_add(&sta->mesh->fail_avg, 1);
  			mesh_path_tx_pending(mpath);
  			/* draft says preq_id should be saved to, but there does
  			 * not seem to be any use for it, skipping by now
  			 */
  		} else
  			spin_unlock_bh(&mpath->state_lock);
  	}
  
  	/* Update and check transmitter routing info */
  	ta = mgmt->sa;
  	if (ether_addr_equal(orig_addr, ta))
  		fresh_info = false;
  	else {
  		fresh_info = true;
  
  		mpath = mesh_path_lookup(sdata, ta);
  		if (mpath) {
  			spin_lock_bh(&mpath->state_lock);
  			if ((mpath->flags & MESH_PATH_FIXED) ||
  				((mpath->flags & MESH_PATH_ACTIVE) &&
  					(last_hop_metric > mpath->metric)))
  				fresh_info = false;
  		} else {
  			mpath = mesh_path_add(sdata, ta);
  			if (IS_ERR(mpath)) {
  				rcu_read_unlock();
  				return 0;
  			}
  			spin_lock_bh(&mpath->state_lock);
  		}
  
  		if (fresh_info) {
  			mesh_path_assign_nexthop(mpath, sta);
  			mpath->metric = last_hop_metric;
  			mpath->exp_time = time_after(mpath->exp_time, exp_time)
  					  ?  mpath->exp_time : exp_time;
  			mesh_path_activate(mpath);
  			spin_unlock_bh(&mpath->state_lock);
  			ewma_mesh_fail_avg_init(&sta->mesh->fail_avg);
  			/* init it at a low value - 0 start is tricky */
  			ewma_mesh_fail_avg_add(&sta->mesh->fail_avg, 1);
  			mesh_path_tx_pending(mpath);
  		} else
  			spin_unlock_bh(&mpath->state_lock);
  	}
  
  	rcu_read_unlock();
  
  	return process ? new_metric : 0;
  }
  
  static void hwmp_preq_frame_process(struct ieee80211_sub_if_data *sdata,
  				    struct ieee80211_mgmt *mgmt,
  				    const u8 *preq_elem, u32 orig_metric)
  {
  	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
  	struct mesh_path *mpath = NULL;
  	const u8 *target_addr, *orig_addr;
  	const u8 *da;
  	u8 target_flags, ttl, flags;
  	u32 orig_sn, target_sn, lifetime, target_metric = 0;
  	bool reply = false;
  	bool forward = true;
  	bool root_is_gate;
  
  	/* Update target SN, if present */
  	target_addr = PREQ_IE_TARGET_ADDR(preq_elem);
  	orig_addr = PREQ_IE_ORIG_ADDR(preq_elem);
  	target_sn = PREQ_IE_TARGET_SN(preq_elem);
  	orig_sn = PREQ_IE_ORIG_SN(preq_elem);
  	target_flags = PREQ_IE_TARGET_F(preq_elem);
  	/* Proactive PREQ gate announcements */
  	flags = PREQ_IE_FLAGS(preq_elem);
  	root_is_gate = !!(flags & RANN_FLAG_IS_GATE);
  
  	mhwmp_dbg(sdata, "received PREQ from %pM\n", orig_addr);
  
  	if (ether_addr_equal(target_addr, sdata->vif.addr)) {
  		mhwmp_dbg(sdata, "PREQ is for us\n");
  		forward = false;
  		reply = true;
  		target_metric = 0;
  		if (time_after(jiffies, ifmsh->last_sn_update +
  					net_traversal_jiffies(sdata)) ||
  		    time_before(jiffies, ifmsh->last_sn_update)) {
  			++ifmsh->sn;
  			ifmsh->last_sn_update = jiffies;
  		}
  		target_sn = ifmsh->sn;
  	} else if (is_broadcast_ether_addr(target_addr) &&
  		   (target_flags & IEEE80211_PREQ_TO_FLAG)) {
  		rcu_read_lock();
  		mpath = mesh_path_lookup(sdata, orig_addr);
  		if (mpath) {
  			if (flags & IEEE80211_PREQ_PROACTIVE_PREP_FLAG) {
  				reply = true;
  				target_addr = sdata->vif.addr;
  				target_sn = ++ifmsh->sn;
  				target_metric = 0;
  				ifmsh->last_sn_update = jiffies;
  			}
  			if (root_is_gate)
  				mesh_path_add_gate(mpath);
  		}
  		rcu_read_unlock();
  	} else {
  		rcu_read_lock();
  		mpath = mesh_path_lookup(sdata, target_addr);
  		if (mpath) {
  			if ((!(mpath->flags & MESH_PATH_SN_VALID)) ||
  					SN_LT(mpath->sn, target_sn)) {
  				mpath->sn = target_sn;
  				mpath->flags |= MESH_PATH_SN_VALID;
  			} else if ((!(target_flags & IEEE80211_PREQ_TO_FLAG)) &&
  					(mpath->flags & MESH_PATH_ACTIVE)) {
  				reply = true;
  				target_metric = mpath->metric;
  				target_sn = mpath->sn;
  				/* Case E2 of sec 13.10.9.3 IEEE 802.11-2012*/
  				target_flags |= IEEE80211_PREQ_TO_FLAG;
  			}
  		}
  		rcu_read_unlock();
  	}
  
  	if (reply) {
  		lifetime = PREQ_IE_LIFETIME(preq_elem);
  		ttl = ifmsh->mshcfg.element_ttl;
  		if (ttl != 0) {
  			mhwmp_dbg(sdata, "replying to the PREQ\n");
  			mesh_path_sel_frame_tx(MPATH_PREP, 0, orig_addr,
  					       orig_sn, 0, target_addr,
  					       target_sn, mgmt->sa, 0, ttl,
  					       lifetime, target_metric, 0,
  					       sdata);
  		} else {
  			ifmsh->mshstats.dropped_frames_ttl++;
  		}
  	}
  
  	if (forward && ifmsh->mshcfg.dot11MeshForwarding) {
  		u32 preq_id;
  		u8 hopcount;
  
  		ttl = PREQ_IE_TTL(preq_elem);
  		lifetime = PREQ_IE_LIFETIME(preq_elem);
  		if (ttl <= 1) {
  			ifmsh->mshstats.dropped_frames_ttl++;
  			return;
  		}
  		mhwmp_dbg(sdata, "forwarding the PREQ from %pM\n", orig_addr);
  		--ttl;
  		preq_id = PREQ_IE_PREQ_ID(preq_elem);
  		hopcount = PREQ_IE_HOPCOUNT(preq_elem) + 1;
  		da = (mpath && mpath->is_root) ?
  			mpath->rann_snd_addr : broadcast_addr;
  
  		if (flags & IEEE80211_PREQ_PROACTIVE_PREP_FLAG) {
  			target_addr = PREQ_IE_TARGET_ADDR(preq_elem);
  			target_sn = PREQ_IE_TARGET_SN(preq_elem);
  		}
  
  		mesh_path_sel_frame_tx(MPATH_PREQ, flags, orig_addr,
  				       orig_sn, target_flags, target_addr,
  				       target_sn, da, hopcount, ttl, lifetime,
  				       orig_metric, preq_id, sdata);
  		if (!is_multicast_ether_addr(da))
  			ifmsh->mshstats.fwded_unicast++;
  		else
  			ifmsh->mshstats.fwded_mcast++;
  		ifmsh->mshstats.fwded_frames++;
  	}
  }
  
  
  static inline struct sta_info *
  next_hop_deref_protected(struct mesh_path *mpath)
  {
  	return rcu_dereference_protected(mpath->next_hop,
  					 lockdep_is_held(&mpath->state_lock));
  }
  
  
  static void hwmp_prep_frame_process(struct ieee80211_sub_if_data *sdata,
  				    struct ieee80211_mgmt *mgmt,
  				    const u8 *prep_elem, u32 metric)
  {
  	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
  	struct mesh_path *mpath;
  	const u8 *target_addr, *orig_addr;
  	u8 ttl, hopcount, flags;
  	u8 next_hop[ETH_ALEN];
  	u32 target_sn, orig_sn, lifetime;
  
  	mhwmp_dbg(sdata, "received PREP from %pM\n",
  		  PREP_IE_TARGET_ADDR(prep_elem));
  
  	orig_addr = PREP_IE_ORIG_ADDR(prep_elem);
  	if (ether_addr_equal(orig_addr, sdata->vif.addr))
  		/* destination, no forwarding required */
  		return;
  
  	if (!ifmsh->mshcfg.dot11MeshForwarding)
  		return;
  
  	ttl = PREP_IE_TTL(prep_elem);
  	if (ttl <= 1) {
  		sdata->u.mesh.mshstats.dropped_frames_ttl++;
  		return;
  	}
  
  	rcu_read_lock();
  	mpath = mesh_path_lookup(sdata, orig_addr);
  	if (mpath)
  		spin_lock_bh(&mpath->state_lock);
  	else
  		goto fail;
  	if (!(mpath->flags & MESH_PATH_ACTIVE)) {
  		spin_unlock_bh(&mpath->state_lock);
  		goto fail;
  	}
  	memcpy(next_hop, next_hop_deref_protected(mpath)->sta.addr, ETH_ALEN);
  	spin_unlock_bh(&mpath->state_lock);
  	--ttl;
  	flags = PREP_IE_FLAGS(prep_elem);
  	lifetime = PREP_IE_LIFETIME(prep_elem);
  	hopcount = PREP_IE_HOPCOUNT(prep_elem) + 1;
  	target_addr = PREP_IE_TARGET_ADDR(prep_elem);
  	target_sn = PREP_IE_TARGET_SN(prep_elem);
  	orig_sn = PREP_IE_ORIG_SN(prep_elem);
  
  	mesh_path_sel_frame_tx(MPATH_PREP, flags, orig_addr, orig_sn, 0,
  			       target_addr, target_sn, next_hop, hopcount,
  			       ttl, lifetime, metric, 0, sdata);
  	rcu_read_unlock();
  
  	sdata->u.mesh.mshstats.fwded_unicast++;
  	sdata->u.mesh.mshstats.fwded_frames++;
  	return;
  
  fail:
  	rcu_read_unlock();
  	sdata->u.mesh.mshstats.dropped_frames_no_route++;
  }
  
  static void hwmp_perr_frame_process(struct ieee80211_sub_if_data *sdata,
  				    struct ieee80211_mgmt *mgmt,
  				    const u8 *perr_elem)
  {
  	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
  	struct mesh_path *mpath;
  	u8 ttl;
  	const u8 *ta, *target_addr;
  	u32 target_sn;
  	u16 target_rcode;
  
  	ta = mgmt->sa;
  	ttl = PERR_IE_TTL(perr_elem);
  	if (ttl <= 1) {
  		ifmsh->mshstats.dropped_frames_ttl++;
  		return;
  	}
  	ttl--;
  	target_addr = PERR_IE_TARGET_ADDR(perr_elem);
  	target_sn = PERR_IE_TARGET_SN(perr_elem);
  	target_rcode = PERR_IE_TARGET_RCODE(perr_elem);
  
  	rcu_read_lock();
  	mpath = mesh_path_lookup(sdata, target_addr);
  	if (mpath) {
  		struct sta_info *sta;
  
  		spin_lock_bh(&mpath->state_lock);
  		sta = next_hop_deref_protected(mpath);
  		if (mpath->flags & MESH_PATH_ACTIVE &&
  		    ether_addr_equal(ta, sta->sta.addr) &&
  		    !(mpath->flags & MESH_PATH_FIXED) &&
  		    (!(mpath->flags & MESH_PATH_SN_VALID) ||
  		    SN_GT(target_sn, mpath->sn)  || target_sn == 0)) {
  			mpath->flags &= ~MESH_PATH_ACTIVE;
  			if (target_sn != 0)
  				mpath->sn = target_sn;
  			else
  				mpath->sn += 1;
  			spin_unlock_bh(&mpath->state_lock);
  			if (!ifmsh->mshcfg.dot11MeshForwarding)
  				goto endperr;
  			mesh_path_error_tx(sdata, ttl, target_addr,
  					   target_sn, target_rcode,
  					   broadcast_addr);
  		} else
  			spin_unlock_bh(&mpath->state_lock);
  	}
  endperr:
  	rcu_read_unlock();
  }
  
  static void hwmp_rann_frame_process(struct ieee80211_sub_if_data *sdata,
  				    struct ieee80211_mgmt *mgmt,
  				    const struct ieee80211_rann_ie *rann)
  {
  	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
  	struct ieee80211_local *local = sdata->local;
  	struct sta_info *sta;
  	struct mesh_path *mpath;
  	u8 ttl, flags, hopcount;
  	const u8 *orig_addr;
  	u32 orig_sn, new_metric, orig_metric, last_hop_metric, interval;
  	bool root_is_gate;
  
  	ttl = rann->rann_ttl;
  	flags = rann->rann_flags;
  	root_is_gate = !!(flags & RANN_FLAG_IS_GATE);
  	orig_addr = rann->rann_addr;
  	orig_sn = le32_to_cpu(rann->rann_seq);
  	interval = le32_to_cpu(rann->rann_interval);
  	hopcount = rann->rann_hopcount;
  	hopcount++;
  	orig_metric = le32_to_cpu(rann->rann_metric);
  
  	/*  Ignore our own RANNs */
  	if (ether_addr_equal(orig_addr, sdata->vif.addr))
  		return;
  
  	mhwmp_dbg(sdata,
  		  "received RANN from %pM via neighbour %pM (is_gate=%d)\n",
  		  orig_addr, mgmt->sa, root_is_gate);
  
  	rcu_read_lock();
  	sta = sta_info_get(sdata, mgmt->sa);
  	if (!sta) {
  		rcu_read_unlock();
  		return;
  	}
  
  	last_hop_metric = airtime_link_metric_get(local, sta);
  	new_metric = orig_metric + last_hop_metric;
  	if (new_metric < orig_metric)
  		new_metric = MAX_METRIC;
  
  	mpath = mesh_path_lookup(sdata, orig_addr);
  	if (!mpath) {
  		mpath = mesh_path_add(sdata, orig_addr);
  		if (IS_ERR(mpath)) {
  			rcu_read_unlock();
  			sdata->u.mesh.mshstats.dropped_frames_no_route++;
  			return;
  		}
  	}
  
  	if (!(SN_LT(mpath->sn, orig_sn)) &&
  	    !(mpath->sn == orig_sn && new_metric < mpath->rann_metric)) {
  		rcu_read_unlock();
  		return;
  	}
  
  	if ((!(mpath->flags & (MESH_PATH_ACTIVE | MESH_PATH_RESOLVING)) ||
  	     (time_after(jiffies, mpath->last_preq_to_root +
  				  root_path_confirmation_jiffies(sdata)) ||
  	     time_before(jiffies, mpath->last_preq_to_root))) &&
  	     !(mpath->flags & MESH_PATH_FIXED) && (ttl != 0)) {
  		mhwmp_dbg(sdata,
  			  "time to refresh root mpath %pM\n",
  			  orig_addr);
  		mesh_queue_preq(mpath, PREQ_Q_F_START | PREQ_Q_F_REFRESH);
  		mpath->last_preq_to_root = jiffies;
  	}
  
  	mpath->sn = orig_sn;
  	mpath->rann_metric = new_metric;
  	mpath->is_root = true;
  	/* Recording RANNs sender address to send individually
  	 * addressed PREQs destined for root mesh STA */
  	memcpy(mpath->rann_snd_addr, mgmt->sa, ETH_ALEN);
  
  	if (root_is_gate)
  		mesh_path_add_gate(mpath);
  
  	if (ttl <= 1) {
  		ifmsh->mshstats.dropped_frames_ttl++;
  		rcu_read_unlock();
  		return;
  	}
  	ttl--;
  
  	if (ifmsh->mshcfg.dot11MeshForwarding) {
  		mesh_path_sel_frame_tx(MPATH_RANN, flags, orig_addr,
  				       orig_sn, 0, NULL, 0, broadcast_addr,
  				       hopcount, ttl, interval,
  				       new_metric, 0, sdata);
  	}
  
  	rcu_read_unlock();
  }
  
  
  void mesh_rx_path_sel_frame(struct ieee80211_sub_if_data *sdata,
  			    struct ieee80211_mgmt *mgmt, size_t len)
  {
  	struct ieee802_11_elems elems;
  	size_t baselen;
  	u32 path_metric;
  	struct sta_info *sta;
  
  	/* need action_code */
  	if (len < IEEE80211_MIN_ACTION_SIZE + 1)
  		return;
  
  	rcu_read_lock();
  	sta = sta_info_get(sdata, mgmt->sa);
  	if (!sta || sta->mesh->plink_state != NL80211_PLINK_ESTAB) {
  		rcu_read_unlock();
  		return;
  	}
  	rcu_read_unlock();
  
  	baselen = (u8 *) mgmt->u.action.u.mesh_action.variable - (u8 *) mgmt;
  	ieee802_11_parse_elems(mgmt->u.action.u.mesh_action.variable,
  			       len - baselen, false, &elems);
  
  	if (elems.preq) {
  		if (elems.preq_len != 37)
  			/* Right now we support just 1 destination and no AE */
  			return;
  		path_metric = hwmp_route_info_get(sdata, mgmt, elems.preq,
  						  MPATH_PREQ);
  		if (path_metric)
  			hwmp_preq_frame_process(sdata, mgmt, elems.preq,
  						path_metric);
  	}
  	if (elems.prep) {
  		if (elems.prep_len != 31)
  			/* Right now we support no AE */
  			return;
  		path_metric = hwmp_route_info_get(sdata, mgmt, elems.prep,
  						  MPATH_PREP);
  		if (path_metric)
  			hwmp_prep_frame_process(sdata, mgmt, elems.prep,
  						path_metric);
  	}
  	if (elems.perr) {
  		if (elems.perr_len != 15)
  			/* Right now we support only one destination per PERR */
  			return;
  		hwmp_perr_frame_process(sdata, mgmt, elems.perr);
  	}
  	if (elems.rann)
  		hwmp_rann_frame_process(sdata, mgmt, elems.rann);
  }
  
  /**
   * mesh_queue_preq - queue a PREQ to a given destination
   *
   * @mpath: mesh path to discover
   * @flags: special attributes of the PREQ to be sent
   *
   * Locking: the function must be called from within a rcu read lock block.
   *
   */
  static void mesh_queue_preq(struct mesh_path *mpath, u8 flags)
  {
  	struct ieee80211_sub_if_data *sdata = mpath->sdata;
  	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
  	struct mesh_preq_queue *preq_node;
  
  	preq_node = kmalloc(sizeof(struct mesh_preq_queue), GFP_ATOMIC);
  	if (!preq_node) {
  		mhwmp_dbg(sdata, "could not allocate PREQ node\n");
  		return;
  	}
  
  	spin_lock_bh(&ifmsh->mesh_preq_queue_lock);
  	if (ifmsh->preq_queue_len == MAX_PREQ_QUEUE_LEN) {
  		spin_unlock_bh(&ifmsh->mesh_preq_queue_lock);
  		kfree(preq_node);
  		if (printk_ratelimit())
  			mhwmp_dbg(sdata, "PREQ node queue full\n");
  		return;
  	}
  
  	spin_lock(&mpath->state_lock);
  	if (mpath->flags & MESH_PATH_REQ_QUEUED) {
  		spin_unlock(&mpath->state_lock);
  		spin_unlock_bh(&ifmsh->mesh_preq_queue_lock);
  		kfree(preq_node);
  		return;
  	}
  
  	memcpy(preq_node->dst, mpath->dst, ETH_ALEN);
  	preq_node->flags = flags;
  
  	mpath->flags |= MESH_PATH_REQ_QUEUED;
  	spin_unlock(&mpath->state_lock);
  
  	list_add_tail(&preq_node->list, &ifmsh->preq_queue.list);
  	++ifmsh->preq_queue_len;
  	spin_unlock_bh(&ifmsh->mesh_preq_queue_lock);
  
  	if (time_after(jiffies, ifmsh->last_preq + min_preq_int_jiff(sdata)))
  		ieee80211_queue_work(&sdata->local->hw, &sdata->work);
  
  	else if (time_before(jiffies, ifmsh->last_preq)) {
  		/* avoid long wait if did not send preqs for a long time
  		 * and jiffies wrapped around
  		 */
  		ifmsh->last_preq = jiffies - min_preq_int_jiff(sdata) - 1;
  		ieee80211_queue_work(&sdata->local->hw, &sdata->work);
  	} else
  		mod_timer(&ifmsh->mesh_path_timer, ifmsh->last_preq +
  						min_preq_int_jiff(sdata));
  }
  
  /**
   * mesh_path_start_discovery - launch a path discovery from the PREQ queue
   *
   * @sdata: local mesh subif
   */
  void mesh_path_start_discovery(struct ieee80211_sub_if_data *sdata)
  {
  	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
  	struct mesh_preq_queue *preq_node;
  	struct mesh_path *mpath;
  	u8 ttl, target_flags = 0;
  	const u8 *da;
  	u32 lifetime;
  
  	spin_lock_bh(&ifmsh->mesh_preq_queue_lock);
  	if (!ifmsh->preq_queue_len ||
  		time_before(jiffies, ifmsh->last_preq +
  				min_preq_int_jiff(sdata))) {
  		spin_unlock_bh(&ifmsh->mesh_preq_queue_lock);
  		return;
  	}
  
  	preq_node = list_first_entry(&ifmsh->preq_queue.list,
  			struct mesh_preq_queue, list);
  	list_del(&preq_node->list);
  	--ifmsh->preq_queue_len;
  	spin_unlock_bh(&ifmsh->mesh_preq_queue_lock);
  
  	rcu_read_lock();
  	mpath = mesh_path_lookup(sdata, preq_node->dst);
  	if (!mpath)
  		goto enddiscovery;
  
  	spin_lock_bh(&mpath->state_lock);
  	if (mpath->flags & (MESH_PATH_DELETED | MESH_PATH_FIXED)) {
  		spin_unlock_bh(&mpath->state_lock);
  		goto enddiscovery;
  	}
  	mpath->flags &= ~MESH_PATH_REQ_QUEUED;
  	if (preq_node->flags & PREQ_Q_F_START) {
  		if (mpath->flags & MESH_PATH_RESOLVING) {
  			spin_unlock_bh(&mpath->state_lock);
  			goto enddiscovery;
  		} else {
  			mpath->flags &= ~MESH_PATH_RESOLVED;
  			mpath->flags |= MESH_PATH_RESOLVING;
  			mpath->discovery_retries = 0;
  			mpath->discovery_timeout = disc_timeout_jiff(sdata);
  		}
  	} else if (!(mpath->flags & MESH_PATH_RESOLVING) ||
  			mpath->flags & MESH_PATH_RESOLVED) {
  		mpath->flags &= ~MESH_PATH_RESOLVING;
  		spin_unlock_bh(&mpath->state_lock);
  		goto enddiscovery;
  	}
  
  	ifmsh->last_preq = jiffies;
  
  	if (time_after(jiffies, ifmsh->last_sn_update +
  				net_traversal_jiffies(sdata)) ||
  	    time_before(jiffies, ifmsh->last_sn_update)) {
  		++ifmsh->sn;
  		sdata->u.mesh.last_sn_update = jiffies;
  	}
  	lifetime = default_lifetime(sdata);
  	ttl = sdata->u.mesh.mshcfg.element_ttl;
  	if (ttl == 0) {
  		sdata->u.mesh.mshstats.dropped_frames_ttl++;
  		spin_unlock_bh(&mpath->state_lock);
  		goto enddiscovery;
  	}
  
  	if (preq_node->flags & PREQ_Q_F_REFRESH)
  		target_flags |= IEEE80211_PREQ_TO_FLAG;
  	else
  		target_flags &= ~IEEE80211_PREQ_TO_FLAG;
  
  	spin_unlock_bh(&mpath->state_lock);
  	da = (mpath->is_root) ? mpath->rann_snd_addr : broadcast_addr;
  	mesh_path_sel_frame_tx(MPATH_PREQ, 0, sdata->vif.addr, ifmsh->sn,
  			       target_flags, mpath->dst, mpath->sn, da, 0,
  			       ttl, lifetime, 0, ifmsh->preq_id++, sdata);
  	mod_timer(&mpath->timer, jiffies + mpath->discovery_timeout);
  
  enddiscovery:
  	rcu_read_unlock();
  	kfree(preq_node);
  }
  
  /**
   * mesh_nexthop_resolve - lookup next hop; conditionally start path discovery
   *
   * @skb: 802.11 frame to be sent
   * @sdata: network subif the frame will be sent through
   *
   * Lookup next hop for given skb and start path discovery if no
   * forwarding information is found.
   *
   * Returns: 0 if the next hop was found and -ENOENT if the frame was queued.
   * skb is freeed here if no mpath could be allocated.
   */
  int mesh_nexthop_resolve(struct ieee80211_sub_if_data *sdata,
  			 struct sk_buff *skb)
  {
  	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
  	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
  	struct mesh_path *mpath;
  	struct sk_buff *skb_to_free = NULL;
  	u8 *target_addr = hdr->addr3;
  	int err = 0;
  
  	/* Nulls are only sent to peers for PS and should be pre-addressed */
  	if (ieee80211_is_qos_nullfunc(hdr->frame_control))
  		return 0;
  
  	rcu_read_lock();
  	err = mesh_nexthop_lookup(sdata, skb);
  	if (!err)
  		goto endlookup;
  
  	/* no nexthop found, start resolving */
  	mpath = mesh_path_lookup(sdata, target_addr);
  	if (!mpath) {
  		mpath = mesh_path_add(sdata, target_addr);
  		if (IS_ERR(mpath)) {
  			mesh_path_discard_frame(sdata, skb);
  			err = PTR_ERR(mpath);
  			goto endlookup;
  		}
  	}
  
  	if (!(mpath->flags & MESH_PATH_RESOLVING))
  		mesh_queue_preq(mpath, PREQ_Q_F_START);
  
  	if (skb_queue_len(&mpath->frame_queue) >= MESH_FRAME_QUEUE_LEN)
  		skb_to_free = skb_dequeue(&mpath->frame_queue);
  
  	info->flags |= IEEE80211_TX_INTFL_NEED_TXPROCESSING;
  	ieee80211_set_qos_hdr(sdata, skb);
  	skb_queue_tail(&mpath->frame_queue, skb);
  	err = -ENOENT;
  	if (skb_to_free)
  		mesh_path_discard_frame(sdata, skb_to_free);
  
  endlookup:
  	rcu_read_unlock();
  	return err;
  }
  
  /**
   * mesh_nexthop_lookup - put the appropriate next hop on a mesh frame. Calling
   * this function is considered "using" the associated mpath, so preempt a path
   * refresh if this mpath expires soon.
   *
   * @skb: 802.11 frame to be sent
   * @sdata: network subif the frame will be sent through
   *
   * Returns: 0 if the next hop was found. Nonzero otherwise.
   */
  int mesh_nexthop_lookup(struct ieee80211_sub_if_data *sdata,
  			struct sk_buff *skb)
  {
  	struct mesh_path *mpath;
  	struct sta_info *next_hop;
  	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
  	u8 *target_addr = hdr->addr3;
  	int err = -ENOENT;
  
  	rcu_read_lock();
  	mpath = mesh_path_lookup(sdata, target_addr);
  
  	if (!mpath || !(mpath->flags & MESH_PATH_ACTIVE))
  		goto endlookup;
  
  	if (time_after(jiffies,
  		       mpath->exp_time -
  		       msecs_to_jiffies(sdata->u.mesh.mshcfg.path_refresh_time)) &&
  	    ether_addr_equal(sdata->vif.addr, hdr->addr4) &&
  	    !(mpath->flags & MESH_PATH_RESOLVING) &&
  	    !(mpath->flags & MESH_PATH_FIXED))
  		mesh_queue_preq(mpath, PREQ_Q_F_START | PREQ_Q_F_REFRESH);
  
  	next_hop = rcu_dereference(mpath->next_hop);
  	if (next_hop) {
  		memcpy(hdr->addr1, next_hop->sta.addr, ETH_ALEN);
  		memcpy(hdr->addr2, sdata->vif.addr, ETH_ALEN);
  		ieee80211_mps_set_frame_flags(sdata, next_hop, hdr);
  		err = 0;
  	}
  
  endlookup:
  	rcu_read_unlock();
  	return err;
  }
  
  void mesh_path_timer(struct timer_list *t)
  {
  	struct mesh_path *mpath = from_timer(mpath, t, timer);
  	struct ieee80211_sub_if_data *sdata = mpath->sdata;
  	int ret;
  
  	if (sdata->local->quiescing)
  		return;
  
  	spin_lock_bh(&mpath->state_lock);
  	if (mpath->flags & MESH_PATH_RESOLVED ||
  			(!(mpath->flags & MESH_PATH_RESOLVING))) {
  		mpath->flags &= ~(MESH_PATH_RESOLVING | MESH_PATH_RESOLVED);
  		spin_unlock_bh(&mpath->state_lock);
  	} else if (mpath->discovery_retries < max_preq_retries(sdata)) {
  		++mpath->discovery_retries;
  		mpath->discovery_timeout *= 2;
  		mpath->flags &= ~MESH_PATH_REQ_QUEUED;
  		spin_unlock_bh(&mpath->state_lock);
  		mesh_queue_preq(mpath, 0);
  	} else {
  		mpath->flags &= ~(MESH_PATH_RESOLVING |
  				  MESH_PATH_RESOLVED |
  				  MESH_PATH_REQ_QUEUED);
  		mpath->exp_time = jiffies;
  		spin_unlock_bh(&mpath->state_lock);
  		if (!mpath->is_gate && mesh_gate_num(sdata) > 0) {
  			ret = mesh_path_send_to_gates(mpath);
  			if (ret)
  				mhwmp_dbg(sdata, "no gate was reachable\n");
  		} else
  			mesh_path_flush_pending(mpath);
  	}
  }
  
  void mesh_path_tx_root_frame(struct ieee80211_sub_if_data *sdata)
  {
  	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
  	u32 interval = ifmsh->mshcfg.dot11MeshHWMPRannInterval;
  	u8 flags, target_flags = 0;
  
  	flags = (ifmsh->mshcfg.dot11MeshGateAnnouncementProtocol)
  			? RANN_FLAG_IS_GATE : 0;
  
  	switch (ifmsh->mshcfg.dot11MeshHWMPRootMode) {
  	case IEEE80211_PROACTIVE_RANN:
  		mesh_path_sel_frame_tx(MPATH_RANN, flags, sdata->vif.addr,
  				       ++ifmsh->sn, 0, NULL, 0, broadcast_addr,
  				       0, ifmsh->mshcfg.element_ttl,
  				       interval, 0, 0, sdata);
  		break;
  	case IEEE80211_PROACTIVE_PREQ_WITH_PREP:
  		flags |= IEEE80211_PREQ_PROACTIVE_PREP_FLAG;
  		/* fall through */
  	case IEEE80211_PROACTIVE_PREQ_NO_PREP:
  		interval = ifmsh->mshcfg.dot11MeshHWMPactivePathToRootTimeout;
  		target_flags |= IEEE80211_PREQ_TO_FLAG |
  				IEEE80211_PREQ_USN_FLAG;
  		mesh_path_sel_frame_tx(MPATH_PREQ, flags, sdata->vif.addr,
  				       ++ifmsh->sn, target_flags,
  				       (u8 *) broadcast_addr, 0, broadcast_addr,
  				       0, ifmsh->mshcfg.element_ttl, interval,
  				       0, ifmsh->preq_id++, sdata);
  		break;
  	default:
  		mhwmp_dbg(sdata, "Proactive mechanism not supported\n");
  		return;
  	}
  }
  