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	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0
 /* Copyright (C) B.A.T.M.A.N. contributors:
  *
  * Edo Monticelli, Antonio Quartulli
  */
 
 #include "tp_meter.h"
 #include "main.h"
 
 #include <linux/atomic.h>
 #include <linux/build_bug.h>
 #include <linux/byteorder/generic.h>
 #include <linux/cache.h>
 #include <linux/compiler.h>
 #include <linux/container_of.h>
 #include <linux/err.h>
 #include <linux/etherdevice.h>
 #include <linux/gfp.h>
 #include <linux/if_ether.h>
 #include <linux/init.h>
 #include <linux/jiffies.h>
 #include <linux/kref.h>
 #include <linux/kthread.h>
 #include <linux/limits.h>
 #include <linux/list.h>
 #include <linux/minmax.h>
 #include <linux/netdevice.h>
 #include <linux/param.h>
 #include <linux/printk.h>
 #include <linux/random.h>
 #include <linux/rculist.h>
 #include <linux/rcupdate.h>
 #include <linux/sched.h>
 #include <linux/skbuff.h>
 #include <linux/slab.h>
 #include <linux/spinlock.h>
 #include <linux/stddef.h>
 #include <linux/string.h>
 #include <linux/timer.h>
 #include <linux/wait.h>
 #include <linux/workqueue.h>
 #include <uapi/linux/batadv_packet.h>
 #include <uapi/linux/batman_adv.h>
 
 #include "hard-interface.h"
 #include "log.h"
 #include "netlink.h"
 #include "originator.h"
 #include "send.h"
 
 /**
  * BATADV_TP_DEF_TEST_LENGTH - Default test length if not specified by the user
  *  in milliseconds
  */
 #define BATADV_TP_DEF_TEST_LENGTH 10000
 
 /**
  * BATADV_TP_AWND - Advertised window by the receiver (in bytes)
  */
 #define BATADV_TP_AWND 0x20000000
 
 /**
  * BATADV_TP_RECV_TIMEOUT - Receiver activity timeout. If the receiver does not
  *  get anything for such amount of milliseconds, the connection is killed
  */
 #define BATADV_TP_RECV_TIMEOUT 1000
 
 /**
  * BATADV_TP_MAX_RTO - Maximum sender timeout. If the sender RTO gets beyond
  * such amount of milliseconds, the receiver is considered unreachable and the
  * connection is killed
  */
 #define BATADV_TP_MAX_RTO 30000
 
 /**
  * BATADV_TP_FIRST_SEQ - First seqno of each session. The number is rather high
  *  in order to immediately trigger a wrap around (test purposes)
  */
 #define BATADV_TP_FIRST_SEQ ((u32)-1 - 2000)
 
 /**
  * BATADV_TP_PLEN - length of the payload (data after the batadv_unicast header)
  *  to simulate
  */
 #define BATADV_TP_PLEN (BATADV_TP_PACKET_LEN - ETH_HLEN - \
             sizeof(struct batadv_unicast_packet))
 
 static u8 batadv_tp_prerandom[4096] __read_mostly;
 
 /**
  * batadv_tp_session_cookie() - generate session cookie based on session ids
  * @session: TP session identifier
  * @icmp_uid: icmp pseudo uid of the tp session
  *
  * Return: 32 bit tp_meter session cookie
  */
 static u32 batadv_tp_session_cookie(const u8 session[2], u8 icmp_uid)
 {
     u32 cookie;
 
     cookie = icmp_uid << 16;
     cookie |= session[0] << 8;
     cookie |= session[1];
 
     return cookie;
 }
 
 /**
  * batadv_tp_cwnd() - compute the new cwnd size
  * @base: base cwnd size value
  * @increment: the value to add to base to get the new size
  * @min: minimum cwnd value (usually MSS)
  *
  * Return the new cwnd size and ensure it does not exceed the Advertised
  * Receiver Window size. It is wrapped around safely.
  * For details refer to Section 3.1 of RFC5681
  *
  * Return: new congestion window size in bytes
  */
 static u32 batadv_tp_cwnd(u32 base, u32 increment, u32 min)
 {
     u32 new_size = base + increment;
 
     /* check for wrap-around */
     if (new_size < base)
         new_size = (u32)ULONG_MAX;
 
     new_size = min_t(u32, new_size, BATADV_TP_AWND);
 
     return max_t(u32, new_size, min);
 }
 
 /**
  * batadv_tp_update_cwnd() - update the Congestion Windows
  * @tp_vars: the private data of the current TP meter session
  * @mss: maximum segment size of transmission
  *
  * 1) if the session is in Slow Start, the CWND has to be increased by 1
  * MSS every unique received ACK
  * 2) if the session is in Congestion Avoidance, the CWND has to be
  * increased by MSS * MSS / CWND for every unique received ACK
  */
 static void batadv_tp_update_cwnd(struct batadv_tp_vars *tp_vars, u32 mss)
 {
     spin_lock_bh(&tp_vars->cwnd_lock);
 
     /* slow start... */
     if (tp_vars->cwnd <= tp_vars->ss_threshold) {
         tp_vars->dec_cwnd = 0;
         tp_vars->cwnd = batadv_tp_cwnd(tp_vars->cwnd, mss, mss);
         spin_unlock_bh(&tp_vars->cwnd_lock);
         return;
     }
 
     /* increment CWND at least of 1 (section 3.1 of RFC5681) */
     tp_vars->dec_cwnd += max_t(u32, 1U << 3,
                    ((mss * mss) << 6) / (tp_vars->cwnd << 3));
     if (tp_vars->dec_cwnd < (mss << 3)) {
         spin_unlock_bh(&tp_vars->cwnd_lock);
         return;
     }
 
     tp_vars->cwnd = batadv_tp_cwnd(tp_vars->cwnd, mss, mss);
     tp_vars->dec_cwnd = 0;
 
     spin_unlock_bh(&tp_vars->cwnd_lock);
 }
 
 /**
  * batadv_tp_update_rto() - calculate new retransmission timeout
  * @tp_vars: the private data of the current TP meter session
  * @new_rtt: new roundtrip time in msec
  */
 static void batadv_tp_update_rto(struct batadv_tp_vars *tp_vars,
                  u32 new_rtt)
 {
     long m = new_rtt;
 
     /* RTT update
      * Details in Section 2.2 and 2.3 of RFC6298
      *
      * It's tricky to understand. Don't lose hair please.
      * Inspired by tcp_rtt_estimator() tcp_input.c
      */
     if (tp_vars->srtt != 0) {
         m -= (tp_vars->srtt >> 3); /* m is now error in rtt est */
         tp_vars->srtt += m; /* rtt = 7/8 srtt + 1/8 new */
         if (m < 0)
             m = -m;
 
         m -= (tp_vars->rttvar >> 2);
         tp_vars->rttvar += m; /* mdev ~= 3/4 rttvar + 1/4 new */
     } else {
         /* first measure getting in */
         tp_vars->srtt = m << 3; /* take the measured time to be srtt */
         tp_vars->rttvar = m << 1; /* new_rtt / 2 */
     }
 
     /* rto = srtt + 4 * rttvar.
      * rttvar is scaled by 4, therefore doesn't need to be multiplied
      */
     tp_vars->rto = (tp_vars->srtt >> 3) + tp_vars->rttvar;
 }
 
 /**
  * batadv_tp_batctl_notify() - send client status result to client
  * @reason: reason for tp meter session stop
  * @dst: destination of tp_meter session
  * @bat_priv: the bat priv with all the soft interface information
  * @start_time: start of transmission in jiffies
  * @total_sent: bytes acked to the receiver
  * @cookie: cookie of tp_meter session
  */
 static void batadv_tp_batctl_notify(enum batadv_tp_meter_reason reason,
                     const u8 *dst, struct batadv_priv *bat_priv,
                     unsigned long start_time, u64 total_sent,
                     u32 cookie)
 {
     u32 test_time;
     u8 result;
     u32 total_bytes;
 
     if (!batadv_tp_is_error(reason)) {
         result = BATADV_TP_REASON_COMPLETE;
         test_time = jiffies_to_msecs(jiffies - start_time);
         total_bytes = total_sent;
     } else {
         result = reason;
         test_time = 0;
         total_bytes = 0;
     }
 
     batadv_netlink_tpmeter_notify(bat_priv, dst, result, test_time,
                       total_bytes, cookie);
 }
 
 /**
  * batadv_tp_batctl_error_notify() - send client error result to client
  * @reason: reason for tp meter session stop
  * @dst: destination of tp_meter session
  * @bat_priv: the bat priv with all the soft interface information
  * @cookie: cookie of tp_meter session
  */
 static void batadv_tp_batctl_error_notify(enum batadv_tp_meter_reason reason,
                       const u8 *dst,
                       struct batadv_priv *bat_priv,
                       u32 cookie)
 {
     batadv_tp_batctl_notify(reason, dst, bat_priv, 0, 0, cookie);
 }
 
 /**
  * batadv_tp_list_find() - find a tp_vars object in the global list
  * @bat_priv: the bat priv with all the soft interface information
  * @dst: the other endpoint MAC address to look for
  *
  * Look for a tp_vars object matching dst as end_point and return it after
  * having increment the refcounter. Return NULL is not found
  *
  * Return: matching tp_vars or NULL when no tp_vars with @dst was found
  */
 static struct batadv_tp_vars *batadv_tp_list_find(struct batadv_priv *bat_priv,
                           const u8 *dst)
 {
     struct batadv_tp_vars *pos, *tp_vars = NULL;
 
     rcu_read_lock();
     hlist_for_each_entry_rcu(pos, &bat_priv->tp_list, list) {
         if (!batadv_compare_eth(pos->other_end, dst))
             continue;
 
         /* most of the time this function is invoked during the normal
          * process..it makes sens to pay more when the session is
          * finished and to speed the process up during the measurement
          */
         if (unlikely(!kref_get_unless_zero(&pos->refcount)))
             continue;
 
         tp_vars = pos;
         break;
     }
     rcu_read_unlock();
 
     return tp_vars;
 }
 
 /**
  * batadv_tp_list_find_session() - find tp_vars session object in the global
  *  list
  * @bat_priv: the bat priv with all the soft interface information
  * @dst: the other endpoint MAC address to look for
  * @session: session identifier
  *
  * Look for a tp_vars object matching dst as end_point, session as tp meter
  * session and return it after having increment the refcounter. Return NULL
  * is not found
  *
  * Return: matching tp_vars or NULL when no tp_vars was found
  */
 static struct batadv_tp_vars *
 batadv_tp_list_find_session(struct batadv_priv *bat_priv, const u8 *dst,
                 const u8 *session)
 {
     struct batadv_tp_vars *pos, *tp_vars = NULL;
 
     rcu_read_lock();
     hlist_for_each_entry_rcu(pos, &bat_priv->tp_list, list) {
         if (!batadv_compare_eth(pos->other_end, dst))
             continue;
 
         if (memcmp(pos->session, session, sizeof(pos->session)) != 0)
             continue;
 
         /* most of the time this function is invoked during the normal
          * process..it makes sense to pay more when the session is
          * finished and to speed the process up during the measurement
          */
         if (unlikely(!kref_get_unless_zero(&pos->refcount)))
             continue;
 
         tp_vars = pos;
         break;
     }
     rcu_read_unlock();
 
     return tp_vars;
 }
 
 /**
  * batadv_tp_vars_release() - release batadv_tp_vars from lists and queue for
  *  free after rcu grace period
  * @ref: kref pointer of the batadv_tp_vars
  */
 static void batadv_tp_vars_release(struct kref *ref)
 {
     struct batadv_tp_vars *tp_vars;
     struct batadv_tp_unacked *un, *safe;
 
     tp_vars = container_of(ref, struct batadv_tp_vars, refcount);
 
     /* lock should not be needed because this object is now out of any
      * context!
      */
     spin_lock_bh(&tp_vars->unacked_lock);
     list_for_each_entry_safe(un, safe, &tp_vars->unacked_list, list) {
         list_del(&un->list);
         kfree(un);
     }
     spin_unlock_bh(&tp_vars->unacked_lock);
 
     kfree_rcu(tp_vars, rcu);
 }
 
 /**
  * batadv_tp_vars_put() - decrement the batadv_tp_vars refcounter and possibly
  *  release it
  * @tp_vars: the private data of the current TP meter session to be free'd
  */
 static void batadv_tp_vars_put(struct batadv_tp_vars *tp_vars)
 {
     if (!tp_vars)
         return;
 
     kref_put(&tp_vars->refcount, batadv_tp_vars_release);
 }
 
 /**
  * batadv_tp_sender_cleanup() - cleanup sender data and drop and timer
  * @bat_priv: the bat priv with all the soft interface information
  * @tp_vars: the private data of the current TP meter session to cleanup
  */
 static void batadv_tp_sender_cleanup(struct batadv_priv *bat_priv,
                      struct batadv_tp_vars *tp_vars)
 {
     cancel_delayed_work(&tp_vars->finish_work);
 
     spin_lock_bh(&tp_vars->bat_priv->tp_list_lock);
     hlist_del_rcu(&tp_vars->list);
     spin_unlock_bh(&tp_vars->bat_priv->tp_list_lock);
 
     /* drop list reference */
     batadv_tp_vars_put(tp_vars);
 
     atomic_dec(&tp_vars->bat_priv->tp_num);
 
     /* kill the timer and remove its reference */
     del_timer_sync(&tp_vars->timer);
     /* the worker might have rearmed itself therefore we kill it again. Note
      * that if the worker should run again before invoking the following
      * del_timer(), it would not re-arm itself once again because the status
      * is OFF now
      */
     del_timer(&tp_vars->timer);
     batadv_tp_vars_put(tp_vars);
 }
 
 /**
  * batadv_tp_sender_end() - print info about ended session and inform client
  * @bat_priv: the bat priv with all the soft interface information
  * @tp_vars: the private data of the current TP meter session
  */
 static void batadv_tp_sender_end(struct batadv_priv *bat_priv,
                  struct batadv_tp_vars *tp_vars)
 {
     u32 session_cookie;
 
     batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
            "Test towards %pM finished..shutting down (reason=%d)\n",
            tp_vars->other_end, tp_vars->reason);
 
     batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
            "Last timing stats: SRTT=%ums RTTVAR=%ums RTO=%ums\n",
            tp_vars->srtt >> 3, tp_vars->rttvar >> 2, tp_vars->rto);
 
     batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
            "Final values: cwnd=%u ss_threshold=%u\n",
            tp_vars->cwnd, tp_vars->ss_threshold);
 
     session_cookie = batadv_tp_session_cookie(tp_vars->session,
                           tp_vars->icmp_uid);
 
     batadv_tp_batctl_notify(tp_vars->reason,
                 tp_vars->other_end,
                 bat_priv,
                 tp_vars->start_time,
                 atomic64_read(&tp_vars->tot_sent),
                 session_cookie);
 }
 
 /**
  * batadv_tp_sender_shutdown() - let sender thread/timer stop gracefully
  * @tp_vars: the private data of the current TP meter session
  * @reason: reason for tp meter session stop
  */
 static void batadv_tp_sender_shutdown(struct batadv_tp_vars *tp_vars,
                       enum batadv_tp_meter_reason reason)
 {
     if (!atomic_dec_and_test(&tp_vars->sending))
         return;
 
     tp_vars->reason = reason;
 }
 
 /**
  * batadv_tp_sender_finish() - stop sender session after test_length was reached
  * @work: delayed work reference of the related tp_vars
  */
 static void batadv_tp_sender_finish(struct work_struct *work)
 {
     struct delayed_work *delayed_work;
     struct batadv_tp_vars *tp_vars;
 
     delayed_work = to_delayed_work(work);
     tp_vars = container_of(delayed_work, struct batadv_tp_vars,
                    finish_work);
 
     batadv_tp_sender_shutdown(tp_vars, BATADV_TP_REASON_COMPLETE);
 }
 
 /**
  * batadv_tp_reset_sender_timer() - reschedule the sender timer
  * @tp_vars: the private TP meter data for this session
  *
  * Reschedule the timer using tp_vars->rto as delay
  */
 static void batadv_tp_reset_sender_timer(struct batadv_tp_vars *tp_vars)
 {
     /* most of the time this function is invoked while normal packet
      * reception...
      */
     if (unlikely(atomic_read(&tp_vars->sending) == 0))
         /* timer ref will be dropped in batadv_tp_sender_cleanup */
         return;
 
     mod_timer(&tp_vars->timer, jiffies + msecs_to_jiffies(tp_vars->rto));
 }
 
 /**
  * batadv_tp_sender_timeout() - timer that fires in case of packet loss
  * @t: address to timer_list inside tp_vars
  *
  * If fired it means that there was packet loss.
  * Switch to Slow Start, set the ss_threshold to half of the current cwnd and
  * reset the cwnd to 3*MSS
  */
 static void batadv_tp_sender_timeout(struct timer_list *t)
 {
     struct batadv_tp_vars *tp_vars = from_timer(tp_vars, t, timer);
     struct batadv_priv *bat_priv = tp_vars->bat_priv;
 
     if (atomic_read(&tp_vars->sending) == 0)
         return;
 
     /* if the user waited long enough...shutdown the test */
     if (unlikely(tp_vars->rto >= BATADV_TP_MAX_RTO)) {
         batadv_tp_sender_shutdown(tp_vars,
                       BATADV_TP_REASON_DST_UNREACHABLE);
         return;
     }
 
     /* RTO exponential backoff
      * Details in Section 5.5 of RFC6298
      */
     tp_vars->rto <<= 1;
 
     spin_lock_bh(&tp_vars->cwnd_lock);
 
     tp_vars->ss_threshold = tp_vars->cwnd >> 1;
     if (tp_vars->ss_threshold < BATADV_TP_PLEN * 2)
         tp_vars->ss_threshold = BATADV_TP_PLEN * 2;
 
     batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
            "Meter: RTO fired during test towards %pM! cwnd=%u new ss_thr=%u, resetting last_sent to %u\n",
            tp_vars->other_end, tp_vars->cwnd, tp_vars->ss_threshold,
            atomic_read(&tp_vars->last_acked));
 
     tp_vars->cwnd = BATADV_TP_PLEN * 3;
 
     spin_unlock_bh(&tp_vars->cwnd_lock);
 
     /* resend the non-ACKed packets.. */
     tp_vars->last_sent = atomic_read(&tp_vars->last_acked);
     wake_up(&tp_vars->more_bytes);
 
     batadv_tp_reset_sender_timer(tp_vars);
 }
 
 /**
  * batadv_tp_fill_prerandom() - Fill buffer with prefetched random bytes
  * @tp_vars: the private TP meter data for this session
  * @buf: Buffer to fill with bytes
  * @nbytes: amount of pseudorandom bytes
  */
 static void batadv_tp_fill_prerandom(struct batadv_tp_vars *tp_vars,
                      u8 *buf, size_t nbytes)
 {
     u32 local_offset;
     size_t bytes_inbuf;
     size_t to_copy;
     size_t pos = 0;
 
     spin_lock_bh(&tp_vars->prerandom_lock);
     local_offset = tp_vars->prerandom_offset;
     tp_vars->prerandom_offset += nbytes;
     tp_vars->prerandom_offset %= sizeof(batadv_tp_prerandom);
     spin_unlock_bh(&tp_vars->prerandom_lock);
 
     while (nbytes) {
         local_offset %= sizeof(batadv_tp_prerandom);
         bytes_inbuf = sizeof(batadv_tp_prerandom) - local_offset;
         to_copy = min(nbytes, bytes_inbuf);
 
         memcpy(&buf[pos], &batadv_tp_prerandom[local_offset], to_copy);
         pos += to_copy;
         nbytes -= to_copy;
         local_offset = 0;
     }
 }
 
 /**
  * batadv_tp_send_msg() - send a single message
  * @tp_vars: the private TP meter data for this session
  * @src: source mac address
  * @orig_node: the originator of the destination
  * @seqno: sequence number of this packet
  * @len: length of the entire packet
  * @session: session identifier
  * @uid: local ICMP "socket" index
  * @timestamp: timestamp in jiffies which is replied in ack
  *
  * Create and send a single TP Meter message.
  *
  * Return: 0 on success, BATADV_TP_REASON_DST_UNREACHABLE if the destination is
  * not reachable, BATADV_TP_REASON_MEMORY_ERROR if the packet couldn't be
  * allocated
  */
 static int batadv_tp_send_msg(struct batadv_tp_vars *tp_vars, const u8 *src,
                   struct batadv_orig_node *orig_node,
                   u32 seqno, size_t len, const u8 *session,
                   int uid, u32 timestamp)
 {
     struct batadv_icmp_tp_packet *icmp;
     struct sk_buff *skb;
     int r;
     u8 *data;
     size_t data_len;
 
     skb = netdev_alloc_skb_ip_align(NULL, len + ETH_HLEN);
     if (unlikely(!skb))
         return BATADV_TP_REASON_MEMORY_ERROR;
 
     skb_reserve(skb, ETH_HLEN);
     icmp = skb_put(skb, sizeof(*icmp));
 
     /* fill the icmp header */
     ether_addr_copy(icmp->dst, orig_node->orig);
     ether_addr_copy(icmp->orig, src);
     icmp->version = BATADV_COMPAT_VERSION;
     icmp->packet_type = BATADV_ICMP;
     icmp->ttl = BATADV_TTL;
     icmp->msg_type = BATADV_TP;
     icmp->uid = uid;
 
     icmp->subtype = BATADV_TP_MSG;
     memcpy(icmp->session, session, sizeof(icmp->session));
     icmp->seqno = htonl(seqno);
     icmp->timestamp = htonl(timestamp);
 
     data_len = len - sizeof(*icmp);
     data = skb_put(skb, data_len);
     batadv_tp_fill_prerandom(tp_vars, data, data_len);
 
     r = batadv_send_skb_to_orig(skb, orig_node, NULL);
     if (r == NET_XMIT_SUCCESS)
         return 0;
 
     return BATADV_TP_REASON_CANT_SEND;
 }
 
 /**
  * batadv_tp_recv_ack() - ACK receiving function
  * @bat_priv: the bat priv with all the soft interface information
  * @skb: the buffer containing the received packet
  *
  * Process a received TP ACK packet
  */
 static void batadv_tp_recv_ack(struct batadv_priv *bat_priv,
                    const struct sk_buff *skb)
 {
     struct batadv_hard_iface *primary_if = NULL;
     struct batadv_orig_node *orig_node = NULL;
     const struct batadv_icmp_tp_packet *icmp;
     struct batadv_tp_vars *tp_vars;
     const unsigned char *dev_addr;
     size_t packet_len, mss;
     u32 rtt, recv_ack, cwnd;
 
     packet_len = BATADV_TP_PLEN;
     mss = BATADV_TP_PLEN;
     packet_len += sizeof(struct batadv_unicast_packet);
 
     icmp = (struct batadv_icmp_tp_packet *)skb->data;
 
     /* find the tp_vars */
     tp_vars = batadv_tp_list_find_session(bat_priv, icmp->orig,
                           icmp->session);
     if (unlikely(!tp_vars))
         return;
 
     if (unlikely(atomic_read(&tp_vars->sending) == 0))
         goto out;
 
     /* old ACK? silently drop it.. */
     if (batadv_seq_before(ntohl(icmp->seqno),
                   (u32)atomic_read(&tp_vars->last_acked)))
         goto out;
 
     primary_if = batadv_primary_if_get_selected(bat_priv);
     if (unlikely(!primary_if))
         goto out;
 
     orig_node = batadv_orig_hash_find(bat_priv, icmp->orig);
     if (unlikely(!orig_node))
         goto out;
 
     /* update RTO with the new sampled RTT, if any */
     rtt = jiffies_to_msecs(jiffies) - ntohl(icmp->timestamp);
     if (icmp->timestamp && rtt)
         batadv_tp_update_rto(tp_vars, rtt);
 
     /* ACK for new data... reset the timer */
     batadv_tp_reset_sender_timer(tp_vars);
 
     recv_ack = ntohl(icmp->seqno);
 
     /* check if this ACK is a duplicate */
     if (atomic_read(&tp_vars->last_acked) == recv_ack) {
         atomic_inc(&tp_vars->dup_acks);
         if (atomic_read(&tp_vars->dup_acks) != 3)
             goto out;
 
         if (recv_ack >= tp_vars->recover)
             goto out;
 
         /* if this is the third duplicate ACK do Fast Retransmit */
         batadv_tp_send_msg(tp_vars, primary_if->net_dev->dev_addr,
                    orig_node, recv_ack, packet_len,
                    icmp->session, icmp->uid,
                    jiffies_to_msecs(jiffies));
 
         spin_lock_bh(&tp_vars->cwnd_lock);
 
         /* Fast Recovery */
         tp_vars->fast_recovery = true;
         /* Set recover to the last outstanding seqno when Fast Recovery
          * is entered. RFC6582, Section 3.2, step 1
          */
         tp_vars->recover = tp_vars->last_sent;
         tp_vars->ss_threshold = tp_vars->cwnd >> 1;
         batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
                "Meter: Fast Recovery, (cur cwnd=%u) ss_thr=%u last_sent=%u recv_ack=%u\n",
                tp_vars->cwnd, tp_vars->ss_threshold,
                tp_vars->last_sent, recv_ack);
         tp_vars->cwnd = batadv_tp_cwnd(tp_vars->ss_threshold, 3 * mss,
                            mss);
         tp_vars->dec_cwnd = 0;
         tp_vars->last_sent = recv_ack;
 
         spin_unlock_bh(&tp_vars->cwnd_lock);
     } else {
         /* count the acked data */
         atomic64_add(recv_ack - atomic_read(&tp_vars->last_acked),
                  &tp_vars->tot_sent);
         /* reset the duplicate ACKs counter */
         atomic_set(&tp_vars->dup_acks, 0);
 
         if (tp_vars->fast_recovery) {
             /* partial ACK */
             if (batadv_seq_before(recv_ack, tp_vars->recover)) {
                 /* this is another hole in the window. React
                  * immediately as specified by NewReno (see
                  * Section 3.2 of RFC6582 for details)
                  */
                 dev_addr = primary_if->net_dev->dev_addr;
                 batadv_tp_send_msg(tp_vars, dev_addr,
                            orig_node, recv_ack,
                            packet_len, icmp->session,
                            icmp->uid,
                            jiffies_to_msecs(jiffies));
                 tp_vars->cwnd = batadv_tp_cwnd(tp_vars->cwnd,
                                    mss, mss);
             } else {
                 tp_vars->fast_recovery = false;
                 /* set cwnd to the value of ss_threshold at the
                  * moment that Fast Recovery was entered.
                  * RFC6582, Section 3.2, step 3
                  */
                 cwnd = batadv_tp_cwnd(tp_vars->ss_threshold, 0,
                               mss);
                 tp_vars->cwnd = cwnd;
             }
             goto move_twnd;
         }
 
         if (recv_ack - atomic_read(&tp_vars->last_acked) >= mss)
             batadv_tp_update_cwnd(tp_vars, mss);
 move_twnd:
         /* move the Transmit Window */
         atomic_set(&tp_vars->last_acked, recv_ack);
     }
 
     wake_up(&tp_vars->more_bytes);
 out:
     batadv_hardif_put(primary_if);
     batadv_orig_node_put(orig_node);
     batadv_tp_vars_put(tp_vars);
 }
 
 /**
  * batadv_tp_avail() - check if congestion window is not full
  * @tp_vars: the private data of the current TP meter session
  * @payload_len: size of the payload of a single message
  *
  * Return: true when congestion window is not full, false otherwise
  */
 static bool batadv_tp_avail(struct batadv_tp_vars *tp_vars,
                 size_t payload_len)
 {
     u32 win_left, win_limit;
 
     win_limit = atomic_read(&tp_vars->last_acked) + tp_vars->cwnd;
     win_left = win_limit - tp_vars->last_sent;
 
     return win_left >= payload_len;
 }
 
 /**
  * batadv_tp_wait_available() - wait until congestion window becomes free or
  *  timeout is reached
  * @tp_vars: the private data of the current TP meter session
  * @plen: size of the payload of a single message
  *
  * Return: 0 if the condition evaluated to false after the timeout elapsed,
  *  1 if the condition evaluated to true after the timeout elapsed, the
  *  remaining jiffies (at least 1) if the condition evaluated to true before
  *  the timeout elapsed, or -ERESTARTSYS if it was interrupted by a signal.
  */
 static int batadv_tp_wait_available(struct batadv_tp_vars *tp_vars, size_t plen)
 {
     int ret;
 
     ret = wait_event_interruptible_timeout(tp_vars->more_bytes,
                            batadv_tp_avail(tp_vars, plen),
                            HZ / 10);
 
     return ret;
 }
 
 /**
  * batadv_tp_send() - main sending thread of a tp meter session
  * @arg: address of the related tp_vars
  *
  * Return: nothing, this function never returns
  */
 static int batadv_tp_send(void *arg)
 {
     struct batadv_tp_vars *tp_vars = arg;
     struct batadv_priv *bat_priv = tp_vars->bat_priv;
     struct batadv_hard_iface *primary_if = NULL;
     struct batadv_orig_node *orig_node = NULL;
     size_t payload_len, packet_len;
     int err = 0;
 
     if (unlikely(tp_vars->role != BATADV_TP_SENDER)) {
         err = BATADV_TP_REASON_DST_UNREACHABLE;
         tp_vars->reason = err;
         goto out;
     }
 
     orig_node = batadv_orig_hash_find(bat_priv, tp_vars->other_end);
     if (unlikely(!orig_node)) {
         err = BATADV_TP_REASON_DST_UNREACHABLE;
         tp_vars->reason = err;
         goto out;
     }
 
     primary_if = batadv_primary_if_get_selected(bat_priv);
     if (unlikely(!primary_if)) {
         err = BATADV_TP_REASON_DST_UNREACHABLE;
         tp_vars->reason = err;
         goto out;
     }
 
     /* assume that all the hard_interfaces have a correctly
      * configured MTU, so use the soft_iface MTU as MSS.
      * This might not be true and in that case the fragmentation
      * should be used.
      * Now, try to send the packet as it is
      */
     payload_len = BATADV_TP_PLEN;
     BUILD_BUG_ON(sizeof(struct batadv_icmp_tp_packet) > BATADV_TP_PLEN);
 
     batadv_tp_reset_sender_timer(tp_vars);
 
     /* queue the worker in charge of terminating the test */
     queue_delayed_work(batadv_event_workqueue, &tp_vars->finish_work,
                msecs_to_jiffies(tp_vars->test_length));
 
     while (atomic_read(&tp_vars->sending) != 0) {
         if (unlikely(!batadv_tp_avail(tp_vars, payload_len))) {
             batadv_tp_wait_available(tp_vars, payload_len);
             continue;
         }
 
         /* to emulate normal unicast traffic, add to the payload len
          * the size of the unicast header
          */
         packet_len = payload_len + sizeof(struct batadv_unicast_packet);
 
         err = batadv_tp_send_msg(tp_vars, primary_if->net_dev->dev_addr,
                      orig_node, tp_vars->last_sent,
                      packet_len,
                      tp_vars->session, tp_vars->icmp_uid,
                      jiffies_to_msecs(jiffies));
 
         /* something went wrong during the preparation/transmission */
         if (unlikely(err && err != BATADV_TP_REASON_CANT_SEND)) {
             batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
                    "Meter: %s() cannot send packets (%d)\n",
                    __func__, err);
             /* ensure nobody else tries to stop the thread now */
             if (atomic_dec_and_test(&tp_vars->sending))
                 tp_vars->reason = err;
             break;
         }
 
         /* right-shift the TWND */
         if (!err)
             tp_vars->last_sent += payload_len;
 
         cond_resched();
     }
 
 out:
     batadv_hardif_put(primary_if);
     batadv_orig_node_put(orig_node);
 
     batadv_tp_sender_end(bat_priv, tp_vars);
     batadv_tp_sender_cleanup(bat_priv, tp_vars);
 
     batadv_tp_vars_put(tp_vars);
 
     return 0;
 }
 
 /**
  * batadv_tp_start_kthread() - start new thread which manages the tp meter
  *  sender
  * @tp_vars: the private data of the current TP meter session
  */
 static void batadv_tp_start_kthread(struct batadv_tp_vars *tp_vars)
 {
     struct task_struct *kthread;
     struct batadv_priv *bat_priv = tp_vars->bat_priv;
     u32 session_cookie;
 
     kref_get(&tp_vars->refcount);
     kthread = kthread_create(batadv_tp_send, tp_vars, "kbatadv_tp_meter");
     if (IS_ERR(kthread)) {
         session_cookie = batadv_tp_session_cookie(tp_vars->session,
                               tp_vars->icmp_uid);
         pr_err("batadv: cannot create tp meter kthread\n");
         batadv_tp_batctl_error_notify(BATADV_TP_REASON_MEMORY_ERROR,
                           tp_vars->other_end,
                           bat_priv, session_cookie);
 
         /* drop reserved reference for kthread */
         batadv_tp_vars_put(tp_vars);
 
         /* cleanup of failed tp meter variables */
         batadv_tp_sender_cleanup(bat_priv, tp_vars);
         return;
     }
 
     wake_up_process(kthread);
 }
 
 /**
  * batadv_tp_start() - start a new tp meter session
  * @bat_priv: the bat priv with all the soft interface information
  * @dst: the receiver MAC address
  * @test_length: test length in milliseconds
  * @cookie: session cookie
  */
 void batadv_tp_start(struct batadv_priv *bat_priv, const u8 *dst,
              u32 test_length, u32 *cookie)
 {
     struct batadv_tp_vars *tp_vars;
     u8 session_id[2];
     u8 icmp_uid;
     u32 session_cookie;
 
     get_random_bytes(session_id, sizeof(session_id));
     get_random_bytes(&icmp_uid, 1);
     session_cookie = batadv_tp_session_cookie(session_id, icmp_uid);
     *cookie = session_cookie;
 
     /* look for an already existing test towards this node */
     spin_lock_bh(&bat_priv->tp_list_lock);
     tp_vars = batadv_tp_list_find(bat_priv, dst);
     if (tp_vars) {
         spin_unlock_bh(&bat_priv->tp_list_lock);
         batadv_tp_vars_put(tp_vars);
         batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
                "Meter: test to or from the same node already ongoing, aborting\n");
         batadv_tp_batctl_error_notify(BATADV_TP_REASON_ALREADY_ONGOING,
                           dst, bat_priv, session_cookie);
         return;
     }
 
     if (!atomic_add_unless(&bat_priv->tp_num, 1, BATADV_TP_MAX_NUM)) {
         spin_unlock_bh(&bat_priv->tp_list_lock);
         batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
                "Meter: too many ongoing sessions, aborting (SEND)\n");
         batadv_tp_batctl_error_notify(BATADV_TP_REASON_TOO_MANY, dst,
                           bat_priv, session_cookie);
         return;
     }
 
     tp_vars = kmalloc(sizeof(*tp_vars), GFP_ATOMIC);
     if (!tp_vars) {
         spin_unlock_bh(&bat_priv->tp_list_lock);
         batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
                "Meter: %s cannot allocate list elements\n",
                __func__);
         batadv_tp_batctl_error_notify(BATADV_TP_REASON_MEMORY_ERROR,
                           dst, bat_priv, session_cookie);
         return;
     }
 
     /* initialize tp_vars */
     ether_addr_copy(tp_vars->other_end, dst);
     kref_init(&tp_vars->refcount);
     tp_vars->role = BATADV_TP_SENDER;
     atomic_set(&tp_vars->sending, 1);
     memcpy(tp_vars->session, session_id, sizeof(session_id));
     tp_vars->icmp_uid = icmp_uid;
 
     tp_vars->last_sent = BATADV_TP_FIRST_SEQ;
     atomic_set(&tp_vars->last_acked, BATADV_TP_FIRST_SEQ);
     tp_vars->fast_recovery = false;
     tp_vars->recover = BATADV_TP_FIRST_SEQ;
 
     /* initialise the CWND to 3*MSS (Section 3.1 in RFC5681).
      * For batman-adv the MSS is the size of the payload received by the
      * soft_interface, hence its MTU
      */
     tp_vars->cwnd = BATADV_TP_PLEN * 3;
     /* at the beginning initialise the SS threshold to the biggest possible
      * window size, hence the AWND size
      */
     tp_vars->ss_threshold = BATADV_TP_AWND;
 
     /* RTO initial value is 3 seconds.
      * Details in Section 2.1 of RFC6298
      */
     tp_vars->rto = 1000;
     tp_vars->srtt = 0;
     tp_vars->rttvar = 0;
 
     atomic64_set(&tp_vars->tot_sent, 0);
 
     kref_get(&tp_vars->refcount);
     timer_setup(&tp_vars->timer, batadv_tp_sender_timeout, 0);
 
     tp_vars->bat_priv = bat_priv;
     tp_vars->start_time = jiffies;
 
     init_waitqueue_head(&tp_vars->more_bytes);
 
     spin_lock_init(&tp_vars->unacked_lock);
     INIT_LIST_HEAD(&tp_vars->unacked_list);
 
     spin_lock_init(&tp_vars->cwnd_lock);
 
     tp_vars->prerandom_offset = 0;
     spin_lock_init(&tp_vars->prerandom_lock);
 
     kref_get(&tp_vars->refcount);
     hlist_add_head_rcu(&tp_vars->list, &bat_priv->tp_list);
     spin_unlock_bh(&bat_priv->tp_list_lock);
 
     tp_vars->test_length = test_length;
     if (!tp_vars->test_length)
         tp_vars->test_length = BATADV_TP_DEF_TEST_LENGTH;
 
     batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
            "Meter: starting throughput meter towards %pM (length=%ums)\n",
            dst, test_length);
 
     /* init work item for finished tp tests */
     INIT_DELAYED_WORK(&tp_vars->finish_work, batadv_tp_sender_finish);
 
     /* start tp kthread. This way the write() call issued from userspace can
      * happily return and avoid to block
      */
     batadv_tp_start_kthread(tp_vars);
 
     /* don't return reference to new tp_vars */
     batadv_tp_vars_put(tp_vars);
 }
 
 /**
  * batadv_tp_stop() - stop currently running tp meter session
  * @bat_priv: the bat priv with all the soft interface information
  * @dst: the receiver MAC address
  * @return_value: reason for tp meter session stop
  */
 void batadv_tp_stop(struct batadv_priv *bat_priv, const u8 *dst,
             u8 return_value)
 {
     struct batadv_orig_node *orig_node;
     struct batadv_tp_vars *tp_vars;
 
     batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
            "Meter: stopping test towards %pM\n", dst);
 
     orig_node = batadv_orig_hash_find(bat_priv, dst);
     if (!orig_node)
         return;
 
     tp_vars = batadv_tp_list_find(bat_priv, orig_node->orig);
     if (!tp_vars) {
         batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
                "Meter: trying to interrupt an already over connection\n");
         goto out;
     }
 
     batadv_tp_sender_shutdown(tp_vars, return_value);
     batadv_tp_vars_put(tp_vars);
 out:
     batadv_orig_node_put(orig_node);
 }
 
 /**
  * batadv_tp_reset_receiver_timer() - reset the receiver shutdown timer
  * @tp_vars: the private data of the current TP meter session
  *
  * start the receiver shutdown timer or reset it if already started
  */
 static void batadv_tp_reset_receiver_timer(struct batadv_tp_vars *tp_vars)
 {
     mod_timer(&tp_vars->timer,
           jiffies + msecs_to_jiffies(BATADV_TP_RECV_TIMEOUT));
 }
 
 /**
  * batadv_tp_receiver_shutdown() - stop a tp meter receiver when timeout is
  *  reached without received ack
  * @t: address to timer_list inside tp_vars
  */
 static void batadv_tp_receiver_shutdown(struct timer_list *t)
 {
     struct batadv_tp_vars *tp_vars = from_timer(tp_vars, t, timer);
     struct batadv_tp_unacked *un, *safe;
     struct batadv_priv *bat_priv;
 
     bat_priv = tp_vars->bat_priv;
 
     /* if there is recent activity rearm the timer */
     if (!batadv_has_timed_out(tp_vars->last_recv_time,
                   BATADV_TP_RECV_TIMEOUT)) {
         /* reset the receiver shutdown timer */
         batadv_tp_reset_receiver_timer(tp_vars);
         return;
     }
 
     batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
            "Shutting down for inactivity (more than %dms) from %pM\n",
            BATADV_TP_RECV_TIMEOUT, tp_vars->other_end);
 
     spin_lock_bh(&tp_vars->bat_priv->tp_list_lock);
     hlist_del_rcu(&tp_vars->list);
     spin_unlock_bh(&tp_vars->bat_priv->tp_list_lock);
 
     /* drop list reference */
     batadv_tp_vars_put(tp_vars);
 
     atomic_dec(&bat_priv->tp_num);
 
     spin_lock_bh(&tp_vars->unacked_lock);
     list_for_each_entry_safe(un, safe, &tp_vars->unacked_list, list) {
         list_del(&un->list);
         kfree(un);
     }
     spin_unlock_bh(&tp_vars->unacked_lock);
 
     /* drop reference of timer */
     batadv_tp_vars_put(tp_vars);
 }
 
 /**
  * batadv_tp_send_ack() - send an ACK packet
  * @bat_priv: the bat priv with all the soft interface information
  * @dst: the mac address of the destination originator
  * @seq: the sequence number to ACK
  * @timestamp: the timestamp to echo back in the ACK
  * @session: session identifier
  * @socket_index: local ICMP socket identifier
  *
  * Return: 0 on success, a positive integer representing the reason of the
  * failure otherwise
  */
 static int batadv_tp_send_ack(struct batadv_priv *bat_priv, const u8 *dst,
                   u32 seq, __be32 timestamp, const u8 *session,
                   int socket_index)
 {
     struct batadv_hard_iface *primary_if = NULL;
     struct batadv_orig_node *orig_node;
     struct batadv_icmp_tp_packet *icmp;
     struct sk_buff *skb;
     int r, ret;
 
     orig_node = batadv_orig_hash_find(bat_priv, dst);
     if (unlikely(!orig_node)) {
         ret = BATADV_TP_REASON_DST_UNREACHABLE;
         goto out;
     }
 
     primary_if = batadv_primary_if_get_selected(bat_priv);
     if (unlikely(!primary_if)) {
         ret = BATADV_TP_REASON_DST_UNREACHABLE;
         goto out;
     }
 
     skb = netdev_alloc_skb_ip_align(NULL, sizeof(*icmp) + ETH_HLEN);
     if (unlikely(!skb)) {
         ret = BATADV_TP_REASON_MEMORY_ERROR;
         goto out;
     }
 
     skb_reserve(skb, ETH_HLEN);
     icmp = skb_put(skb, sizeof(*icmp));
     icmp->packet_type = BATADV_ICMP;
     icmp->version = BATADV_COMPAT_VERSION;
     icmp->ttl = BATADV_TTL;
     icmp->msg_type = BATADV_TP;
     ether_addr_copy(icmp->dst, orig_node->orig);
     ether_addr_copy(icmp->orig, primary_if->net_dev->dev_addr);
     icmp->uid = socket_index;
 
     icmp->subtype = BATADV_TP_ACK;
     memcpy(icmp->session, session, sizeof(icmp->session));
     icmp->seqno = htonl(seq);
     icmp->timestamp = timestamp;
 
     /* send the ack */
     r = batadv_send_skb_to_orig(skb, orig_node, NULL);
     if (unlikely(r < 0) || r == NET_XMIT_DROP) {
         ret = BATADV_TP_REASON_DST_UNREACHABLE;
         goto out;
     }
     ret = 0;
 
 out:
     batadv_orig_node_put(orig_node);
     batadv_hardif_put(primary_if);
 
     return ret;
 }
 
 /**
  * batadv_tp_handle_out_of_order() - store an out of order packet
  * @tp_vars: the private data of the current TP meter session
  * @skb: the buffer containing the received packet
  *
  * Store the out of order packet in the unacked list for late processing. This
  * packets are kept in this list so that they can be ACKed at once as soon as
  * all the previous packets have been received
  *
  * Return: true if the packed has been successfully processed, false otherwise
  */
 static bool batadv_tp_handle_out_of_order(struct batadv_tp_vars *tp_vars,
                       const struct sk_buff *skb)
 {
     const struct batadv_icmp_tp_packet *icmp;
     struct batadv_tp_unacked *un, *new;
     u32 payload_len;
     bool added = false;
 
     new = kmalloc(sizeof(*new), GFP_ATOMIC);
     if (unlikely(!new))
         return false;
 
     icmp = (struct batadv_icmp_tp_packet *)skb->data;
 
     new->seqno = ntohl(icmp->seqno);
     payload_len = skb->len - sizeof(struct batadv_unicast_packet);
     new->len = payload_len;
 
     spin_lock_bh(&tp_vars->unacked_lock);
     /* if the list is empty immediately attach this new object */
     if (list_empty(&tp_vars->unacked_list)) {
         list_add(&new->list, &tp_vars->unacked_list);
         goto out;
     }
 
     /* otherwise loop over the list and either drop the packet because this
      * is a duplicate or store it at the right position.
      *
      * The iteration is done in the reverse way because it is likely that
      * the last received packet (the one being processed now) has a bigger
      * seqno than all the others already stored.
      */
     list_for_each_entry_reverse(un, &tp_vars->unacked_list, list) {
         /* check for duplicates */
         if (new->seqno == un->seqno) {
             if (new->len > un->len)
                 un->len = new->len;
             kfree(new);
             added = true;
             break;
         }
 
         /* look for the right position */
         if (batadv_seq_before(new->seqno, un->seqno))
             continue;
 
         /* as soon as an entry having a bigger seqno is found, the new
          * one is attached _after_ it. In this way the list is kept in
          * ascending order
          */
         list_add_tail(&new->list, &un->list);
         added = true;
         break;
     }
 
     /* received packet with smallest seqno out of order; add it to front */
     if (!added)
         list_add(&new->list, &tp_vars->unacked_list);
 
 out:
     spin_unlock_bh(&tp_vars->unacked_lock);
 
     return true;
 }
 
 /**
  * batadv_tp_ack_unordered() - update number received bytes in current stream
  *  without gaps
  * @tp_vars: the private data of the current TP meter session
  */
 static void batadv_tp_ack_unordered(struct batadv_tp_vars *tp_vars)
 {
     struct batadv_tp_unacked *un, *safe;
     u32 to_ack;
 
     /* go through the unacked packet list and possibly ACK them as
      * well
      */
     spin_lock_bh(&tp_vars->unacked_lock);
     list_for_each_entry_safe(un, safe, &tp_vars->unacked_list, list) {
         /* the list is ordered, therefore it is possible to stop as soon
          * there is a gap between the last acked seqno and the seqno of
          * the packet under inspection
          */
         if (batadv_seq_before(tp_vars->last_recv, un->seqno))
             break;
 
         to_ack = un->seqno + un->len - tp_vars->last_recv;
 
         if (batadv_seq_before(tp_vars->last_recv, un->seqno + un->len))
             tp_vars->last_recv += to_ack;
 
         list_del(&un->list);
         kfree(un);
     }
     spin_unlock_bh(&tp_vars->unacked_lock);
 }
 
 /**
  * batadv_tp_init_recv() - return matching or create new receiver tp_vars
  * @bat_priv: the bat priv with all the soft interface information
  * @icmp: received icmp tp msg
  *
  * Return: corresponding tp_vars or NULL on errors
  */
 static struct batadv_tp_vars *
 batadv_tp_init_recv(struct batadv_priv *bat_priv,
             const struct batadv_icmp_tp_packet *icmp)
 {
     struct batadv_tp_vars *tp_vars;
 
     spin_lock_bh(&bat_priv->tp_list_lock);
     tp_vars = batadv_tp_list_find_session(bat_priv, icmp->orig,
                           icmp->session);
     if (tp_vars)
         goto out_unlock;
 
     if (!atomic_add_unless(&bat_priv->tp_num, 1, BATADV_TP_MAX_NUM)) {
         batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
                "Meter: too many ongoing sessions, aborting (RECV)\n");
         goto out_unlock;
     }
 
     tp_vars = kmalloc(sizeof(*tp_vars), GFP_ATOMIC);
     if (!tp_vars)
         goto out_unlock;
 
     ether_addr_copy(tp_vars->other_end, icmp->orig);
     tp_vars->role = BATADV_TP_RECEIVER;
     memcpy(tp_vars->session, icmp->session, sizeof(tp_vars->session));
     tp_vars->last_recv = BATADV_TP_FIRST_SEQ;
     tp_vars->bat_priv = bat_priv;
     kref_init(&tp_vars->refcount);
 
     spin_lock_init(&tp_vars->unacked_lock);
     INIT_LIST_HEAD(&tp_vars->unacked_list);
 
     kref_get(&tp_vars->refcount);
     hlist_add_head_rcu(&tp_vars->list, &bat_priv->tp_list);
 
     kref_get(&tp_vars->refcount);
     timer_setup(&tp_vars->timer, batadv_tp_receiver_shutdown, 0);
 
     batadv_tp_reset_receiver_timer(tp_vars);
 
 out_unlock:
     spin_unlock_bh(&bat_priv->tp_list_lock);
 
     return tp_vars;
 }
 
 /**
  * batadv_tp_recv_msg() - process a single data message
  * @bat_priv: the bat priv with all the soft interface information
  * @skb: the buffer containing the received packet
  *
  * Process a received TP MSG packet
  */
 static void batadv_tp_recv_msg(struct batadv_priv *bat_priv,
                    const struct sk_buff *skb)
 {
     const struct batadv_icmp_tp_packet *icmp;
     struct batadv_tp_vars *tp_vars;
     size_t packet_size;
     u32 seqno;
 
     icmp = (struct batadv_icmp_tp_packet *)skb->data;
 
     seqno = ntohl(icmp->seqno);
     /* check if this is the first seqno. This means that if the
      * first packet is lost, the tp meter does not work anymore!
      */
     if (seqno == BATADV_TP_FIRST_SEQ) {
         tp_vars = batadv_tp_init_recv(bat_priv, icmp);
         if (!tp_vars) {
             batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
                    "Meter: seqno != BATADV_TP_FIRST_SEQ cannot initiate connection\n");
             goto out;
         }
     } else {
         tp_vars = batadv_tp_list_find_session(bat_priv, icmp->orig,
                               icmp->session);
         if (!tp_vars) {
             batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
                    "Unexpected packet from %pM!\n",
                    icmp->orig);
             goto out;
         }
     }
 
     if (unlikely(tp_vars->role != BATADV_TP_RECEIVER)) {
         batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
                "Meter: dropping packet: not expected (role=%u)\n",
                tp_vars->role);
         goto out;
     }
 
     tp_vars->last_recv_time = jiffies;
 
     /* if the packet is a duplicate, it may be the case that an ACK has been
      * lost. Resend the ACK
      */
     if (batadv_seq_before(seqno, tp_vars->last_recv))
         goto send_ack;
 
     /* if the packet is out of order enqueue it */
     if (ntohl(icmp->seqno) != tp_vars->last_recv) {
         /* exit immediately (and do not send any ACK) if the packet has
          * not been enqueued correctly
          */
         if (!batadv_tp_handle_out_of_order(tp_vars, skb))
             goto out;
 
         /* send a duplicate ACK */
         goto send_ack;
     }
 
     /* if everything was fine count the ACKed bytes */
     packet_size = skb->len - sizeof(struct batadv_unicast_packet);
     tp_vars->last_recv += packet_size;
 
     /* check if this ordered message filled a gap.... */
     batadv_tp_ack_unordered(tp_vars);
 
 send_ack:
     /* send the ACK. If the received packet was out of order, the ACK that
      * is going to be sent is a duplicate (the sender will count them and
      * possibly enter Fast Retransmit as soon as it has reached 3)
      */
     batadv_tp_send_ack(bat_priv, icmp->orig, tp_vars->last_recv,
                icmp->timestamp, icmp->session, icmp->uid);
 out:
     batadv_tp_vars_put(tp_vars);
 }
 
 /**
  * batadv_tp_meter_recv() - main TP Meter receiving function
  * @bat_priv: the bat priv with all the soft interface information
  * @skb: the buffer containing the received packet
  */
 void batadv_tp_meter_recv(struct batadv_priv *bat_priv, struct sk_buff *skb)
 {
     struct batadv_icmp_tp_packet *icmp;
 
     icmp = (struct batadv_icmp_tp_packet *)skb->data;
 
     switch (icmp->subtype) {
     case BATADV_TP_MSG:
         batadv_tp_recv_msg(bat_priv, skb);
         break;
     case BATADV_TP_ACK:
         batadv_tp_recv_ack(bat_priv, skb);
         break;
     default:
         batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
                "Received unknown TP Metric packet type %u\n",
                icmp->subtype);
     }
     consume_skb(skb);
 }
 
 /**
  * batadv_tp_meter_init() - initialize global tp_meter structures
  */
 void __init batadv_tp_meter_init(void)
 {
     get_random_bytes(batadv_tp_prerandom, sizeof(batadv_tp_prerandom));
 }

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