Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1351 insertions, 0 deletions

diff --git a/net/mac80211/mesh_hwmp.c b/net/mac80211/mesh_hwmp.c
new file mode 100644
index 0000000000..5136907298
--- /dev/null
+++ b/net/mac80211/mesh_hwmp.c
@@ -0,0 +1,1351 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2008, 2009 open80211s Ltd.
+ * Copyright (C) 2019, 2021-2023 Intel Corporation
+ * Author:     Luis Carlos Cobo <luisca@cozybit.com>
+ */
+
+#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->control.flags |= IEEE80211_TX_INTCFL_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 +
+			    IEEE80211_ENCRYPT_HEADROOM +
+			    IEEE80211_ENCRYPT_TAILROOM +
+			    hdr_len +
+			    2 + 15 /* PERR IE */);
+	if (!skb)
+		return -1;
+	skb_reserve(skb, local->tx_headroom + IEEE80211_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 ieee80211_tx_status *st)
+{
+	struct ieee80211_tx_info *txinfo = st->info;
+	int failed;
+	struct rate_info rinfo;
+
+	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);
+
+	/* use rate info set by the driver directly if present */
+	if (st->n_rates)
+		rinfo = sta->deflink.tx_stats.last_rate_info;
+	else
+		sta_set_rate_info_tx(sta, &sta->deflink.tx_stats.last_rate, &rinfo);
+
+	ewma_mesh_tx_rate_avg_add(&sta->mesh->tx_rate_avg,
+				  cfg80211_calculate_bitrate(&rinfo));
+}
+
+u32 airtime_link_metric_get(struct ieee80211_local *local,
+			    struct sta_info *sta)
+{
+	/* 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);
+
+	if (sta->mesh->plink_state != NL80211_PLINK_ESTAB)
+		return MAX_METRIC;
+
+	/* 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;
+
+		rate = ewma_mesh_tx_rate_avg_read(&sta->mesh->tx_rate_avg);
+		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 = ((u64)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 flush_mpath = false;
+	bool process = true;
+	u8 hopcount;
+
+	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);
+		hopcount = PREQ_IE_HOPCOUNT(hwmp_ie) + 1;
+		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);
+		hopcount = PREP_IE_HOPCOUNT(hwmp_ie) + 1;
+		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 &&
+				     (rcu_access_pointer(mpath->next_hop) !=
+						      sta ?
+					      mult_frac(new_metric, 10, 9) :
+					      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) {
+			if (rcu_access_pointer(mpath->next_hop) != sta) {
+				mpath->path_change_count++;
+				flush_mpath = true;
+			}
+			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;
+			mpath->hop_count = hopcount;
+			mesh_path_activate(mpath);
+			spin_unlock_bh(&mpath->state_lock);
+			if (flush_mpath)
+				mesh_fast_tx_flush_mpath(mpath);
+			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) &&
+			     ((rcu_access_pointer(mpath->next_hop) != sta ?
+				       mult_frac(last_hop_metric, 10, 9) :
+				       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) {
+			if (rcu_access_pointer(mpath->next_hop) != sta) {
+				mpath->path_change_count++;
+				flush_mpath = true;
+			}
+			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;
+			mpath->hop_count = 1;
+			mesh_path_activate(mpath);
+			spin_unlock_bh(&mpath->state_lock);
+			if (flush_mpath)
+				mesh_fast_tx_flush_mpath(mpath);
+			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 (SN_GT(target_sn, ifmsh->sn))
+			ifmsh->sn = target_sn;
+
+		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;
+	elems = ieee802_11_parse_elems(mgmt->u.action.u.mesh_action.variable,
+				       len - baselen, false, NULL);
+	if (!elems)
+		return;
+
+	if (elems->preq) {
+		if (elems->preq_len != 37)
+			/* Right now we support just 1 destination and no AE */
+			goto free;
+		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 */
+			goto free;
+		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 */
+			goto free;
+		hwmp_perr_frame_process(sdata, mgmt, elems->perr);
+	}
+	if (elems->rann)
+		hwmp_rann_frame_process(sdata, mgmt, elems->rann);
+free:
+	kfree(elems);
+}
+
+/**
+ * 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)))
+		wiphy_work_queue(sdata->local->hw.wiphy, &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;
+		wiphy_work_queue(sdata->local->hw.wiphy, &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);
+
+	spin_lock_bh(&mpath->state_lock);
+	if (!(mpath->flags & MESH_PATH_DELETED))
+		mod_timer(&mpath->timer, jiffies + mpath->discovery_timeout);
+	spin_unlock_bh(&mpath->state_lock);
+
+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 freed 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;
+
+	/* Nulls are only sent to peers for PS and should be pre-addressed */
+	if (ieee80211_is_qos_nullfunc(hdr->frame_control))
+		return 0;
+
+	/* Allow injected packets to bypass mesh routing */
+	if (info->control.flags & IEEE80211_TX_CTRL_SKIP_MPATH_LOOKUP)
+		return 0;
+
+	if (!mesh_nexthop_lookup(sdata, skb))
+		return 0;
+
+	/* 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);
+			return PTR_ERR(mpath);
+		}
+	}
+
+	if (!(mpath->flags & MESH_PATH_RESOLVING) &&
+	    mesh_path_sel_is_hwmp(sdata))
+		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->control.flags |= IEEE80211_TX_INTCFL_NEED_TXPROCESSING;
+	ieee80211_set_qos_hdr(sdata, skb);
+	skb_queue_tail(&mpath->frame_queue, skb);
+	if (skb_to_free)
+		mesh_path_discard_frame(sdata, skb_to_free);
+
+	return -ENOENT;
+}
+
+/**
+ * mesh_nexthop_lookup_nolearn - try to set next hop without path discovery
+ * @skb: 802.11 frame to be sent
+ * @sdata: network subif the frame will be sent through
+ *
+ * Check if the meshDA (addr3) of a unicast frame is a direct neighbor.
+ * And if so, set the RA (addr1) to it to transmit to this node directly,
+ * avoiding PREQ/PREP path discovery.
+ *
+ * Returns: 0 if the next hop was found and -ENOENT otherwise.
+ */
+static int mesh_nexthop_lookup_nolearn(struct ieee80211_sub_if_data *sdata,
+				       struct sk_buff *skb)
+{
+	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
+	struct sta_info *sta;
+
+	if (is_multicast_ether_addr(hdr->addr1))
+		return -ENOENT;
+
+	rcu_read_lock();
+	sta = sta_info_get(sdata, hdr->addr3);
+
+	if (!sta || sta->mesh->plink_state != NL80211_PLINK_ESTAB) {
+		rcu_read_unlock();
+		return -ENOENT;
+	}
+	rcu_read_unlock();
+
+	memcpy(hdr->addr1, hdr->addr3, ETH_ALEN);
+	memcpy(hdr->addr2, sdata->vif.addr, ETH_ALEN);
+	return 0;
+}
+
+void mesh_path_refresh(struct ieee80211_sub_if_data *sdata,
+		       struct mesh_path *mpath, const u8 *addr)
+{
+	if (mpath->flags & (MESH_PATH_REQ_QUEUED | MESH_PATH_FIXED |
+			    MESH_PATH_RESOLVING))
+		return;
+
+	if (time_after(jiffies,
+		       mpath->exp_time -
+		       msecs_to_jiffies(sdata->u.mesh.mshcfg.path_refresh_time)) &&
+	    (!addr || ether_addr_equal(sdata->vif.addr, addr)))
+		mesh_queue_preq(mpath, PREQ_Q_F_START | PREQ_Q_F_REFRESH);
+}
+
+/**
+ * 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 ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
+	struct mesh_path *mpath;
+	struct sta_info *next_hop;
+	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
+	u8 *target_addr = hdr->addr3;
+
+	if (ifmsh->mshcfg.dot11MeshNolearn &&
+	    !mesh_nexthop_lookup_nolearn(sdata, skb))
+		return 0;
+
+	mpath = mesh_path_lookup(sdata, target_addr);
+	if (!mpath || !(mpath->flags & MESH_PATH_ACTIVE))
+		return -ENOENT;
+
+	mesh_path_refresh(sdata, mpath, hdr->addr4);
+
+	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);
+		if (ieee80211_hw_check(&sdata->local->hw, SUPPORT_FAST_XMIT))
+			mesh_fast_tx_cache(sdata, skb, mpath);
+		return 0;
+	}
+
+	return -ENOENT;
+}
+
+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;
+		fallthrough;
+	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;
+	}
+}