// SPDX-License-Identifier: GPL-2.0
/* Copyright 2011-2014 Autronica Fire and Security AS
 *
 * Author(s):
 *      2011-2014 Arvid Brodin, arvid.brodin@alten.se
 *
 * The HSR spec says never to forward the same frame twice on the same
 * interface. A frame is identified by its source MAC address and its HSR
 * sequence number. This code keeps track of senders and their sequence numbers
 * to allow filtering of duplicate frames, and to detect HSR ring errors.
 * Same code handles filtering of duplicates for PRP as well.
 */

#include <kunit/visibility.h>
#include <linux/if_ether.h>
#include <linux/etherdevice.h>
#include <linux/slab.h>
#include <linux/rculist.h>
#include "hsr_main.h"
#include "hsr_framereg.h"
#include "hsr_netlink.h"

bool hsr_addr_is_redbox(struct hsr_priv *hsr, unsigned char *addr)
{
        if (!hsr->redbox || !is_valid_ether_addr(hsr->macaddress_redbox))
                return false;

        return ether_addr_equal(addr, hsr->macaddress_redbox);
}

bool hsr_addr_is_self(struct hsr_priv *hsr, unsigned char *addr)
{
        struct hsr_self_node *sn;
        bool ret = false;

        rcu_read_lock();
        sn = rcu_dereference(hsr->self_node);
        if (!sn) {
                WARN_ONCE(1, "HSR: No self node\n");
                goto out;
        }

        if (ether_addr_equal(addr, sn->macaddress_A) ||
            ether_addr_equal(addr, sn->macaddress_B))
                ret = true;
out:
        rcu_read_unlock();
        return ret;
}

/* Search for mac entry. Caller must hold rcu read lock.
 */
static struct hsr_node *find_node_by_addr_A(struct list_head *node_db,
                                            const unsigned char addr[ETH_ALEN])
{
        struct hsr_node *node;

        list_for_each_entry_rcu(node, node_db, mac_list) {
                if (ether_addr_equal(node->macaddress_A, addr))
                        return node;
        }

        return NULL;
}

/* Check if node for a given MAC address is already present in data base
 */
bool hsr_is_node_in_db(struct list_head *node_db,
                       const unsigned char addr[ETH_ALEN])
{
        return !!find_node_by_addr_A(node_db, addr);
}

/* Helper for device init; the self_node is used in hsr_rcv() to recognize
 * frames from self that's been looped over the HSR ring.
 */
int hsr_create_self_node(struct hsr_priv *hsr,
                         const unsigned char addr_a[ETH_ALEN],
                         const unsigned char addr_b[ETH_ALEN])
{
        struct hsr_self_node *sn, *old;

        sn = kmalloc_obj(*sn);
        if (!sn)
                return -ENOMEM;

        ether_addr_copy(sn->macaddress_A, addr_a);
        ether_addr_copy(sn->macaddress_B, addr_b);

        spin_lock_bh(&hsr->list_lock);
        old = rcu_replace_pointer(hsr->self_node, sn,
                                  lockdep_is_held(&hsr->list_lock));
        spin_unlock_bh(&hsr->list_lock);

        if (old)
                kfree_rcu(old, rcu_head);
        return 0;
}

void hsr_del_self_node(struct hsr_priv *hsr)
{
        struct hsr_self_node *old;

        spin_lock_bh(&hsr->list_lock);
        old = rcu_replace_pointer(hsr->self_node, NULL,
                                  lockdep_is_held(&hsr->list_lock));
        spin_unlock_bh(&hsr->list_lock);
        if (old)
                kfree_rcu(old, rcu_head);
}

static void hsr_free_node(struct hsr_node *node)
{
        xa_destroy(&node->seq_blocks);
        kfree(node->block_buf);
        kfree(node);
}

static void hsr_free_node_rcu(struct rcu_head *rn)
{
        struct hsr_node *node = container_of(rn, struct hsr_node, rcu_head);

        hsr_free_node(node);
}

static void hsr_lock_seq_out_pair(struct hsr_node *node_a,
                                  struct hsr_node *node_b)
{
        if (node_a == node_b) {
                spin_lock_bh(&node_a->seq_out_lock);
                return;
        }

        if (node_a < node_b) {
                spin_lock_bh(&node_a->seq_out_lock);
                spin_lock_nested(&node_b->seq_out_lock, SINGLE_DEPTH_NESTING);
        } else {
                spin_lock_bh(&node_b->seq_out_lock);
                spin_lock_nested(&node_a->seq_out_lock, SINGLE_DEPTH_NESTING);
        }
}

static void hsr_unlock_seq_out_pair(struct hsr_node *node_a,
                                    struct hsr_node *node_b)
{
        if (node_a == node_b) {
                spin_unlock_bh(&node_a->seq_out_lock);
                return;
        }

        if (node_a < node_b) {
                spin_unlock(&node_b->seq_out_lock);
                spin_unlock_bh(&node_a->seq_out_lock);
        } else {
                spin_unlock(&node_a->seq_out_lock);
                spin_unlock_bh(&node_b->seq_out_lock);
        }
}

void hsr_del_nodes(struct list_head *node_db)
{
        struct hsr_node *node;
        struct hsr_node *tmp;

        list_for_each_entry_safe(node, tmp, node_db, mac_list) {
                list_del(&node->mac_list);
                hsr_free_node(node);
        }
}

void prp_handle_san_frame(bool san, enum hsr_port_type port,
                          struct hsr_node *node)
{
        /* Mark if the SAN node is over LAN_A or LAN_B */
        if (port == HSR_PT_SLAVE_A) {
                node->san_a = true;
                return;
        }

        if (port == HSR_PT_SLAVE_B)
                node->san_b = true;
}

/* Allocate an hsr_node and add it to node_db. 'addr' is the node's address_A.
 */
static struct hsr_node *hsr_add_node(struct hsr_priv *hsr,
                                     struct list_head *node_db,
                                     unsigned char addr[], bool san,
                                     enum hsr_port_type rx_port)
{
        struct hsr_node *new_node, *node = NULL;
        unsigned long now;
        size_t block_sz;
        int i;

        new_node = kzalloc_obj(*new_node, GFP_ATOMIC);
        if (!new_node)
                return NULL;

        ether_addr_copy(new_node->macaddress_A, addr);
        spin_lock_init(&new_node->seq_out_lock);

        if (hsr->prot_version == PRP_V1)
                new_node->seq_port_cnt = 1;
        else
                new_node->seq_port_cnt = HSR_PT_PORTS - 1;

        block_sz = hsr_seq_block_size(new_node);
        new_node->block_buf = kcalloc(HSR_MAX_SEQ_BLOCKS, block_sz, GFP_ATOMIC);
        if (!new_node->block_buf)
                goto free;

        xa_init(&new_node->seq_blocks);

        /* We are only interested in time diffs here, so use current jiffies
         * as initialization. (0 could trigger an spurious ring error warning).
         */
        now = jiffies;
        for (i = 0; i < HSR_PT_PORTS; i++) {
                new_node->time_in[i] = now;
        }

        if (san && hsr->proto_ops->handle_san_frame)
                hsr->proto_ops->handle_san_frame(san, rx_port, new_node);

        spin_lock_bh(&hsr->list_lock);
        list_for_each_entry_rcu(node, node_db, mac_list,
                                lockdep_is_held(&hsr->list_lock)) {
                if (ether_addr_equal(node->macaddress_A, addr))
                        goto out;
                if (ether_addr_equal(node->macaddress_B, addr))
                        goto out;
        }
        list_add_tail_rcu(&new_node->mac_list, node_db);
        spin_unlock_bh(&hsr->list_lock);
        return new_node;
out:
        spin_unlock_bh(&hsr->list_lock);
        kfree(new_node->block_buf);
free:
        kfree(new_node);
        return node;
}

void prp_update_san_info(struct hsr_node *node, bool is_sup)
{
        if (!is_sup)
                return;

        node->san_a = false;
        node->san_b = false;
}

/* Get the hsr_node from which 'skb' was sent.
 */
struct hsr_node *hsr_get_node(struct hsr_port *port, struct list_head *node_db,
                              struct sk_buff *skb, bool is_sup,
                              enum hsr_port_type rx_port)
{
        struct hsr_priv *hsr = port->hsr;
        struct hsr_node *node;
        struct ethhdr *ethhdr;
        struct prp_rct *rct;
        bool san = false;

        if (!skb_mac_header_was_set(skb))
                return NULL;

        ethhdr = (struct ethhdr *)skb_mac_header(skb);

        list_for_each_entry_rcu(node, node_db, mac_list) {
                if (ether_addr_equal(node->macaddress_A, ethhdr->h_source)) {
                        if (hsr->proto_ops->update_san_info)
                                hsr->proto_ops->update_san_info(node, is_sup);
                        return node;
                }
                if (ether_addr_equal(node->macaddress_B, ethhdr->h_source)) {
                        if (hsr->proto_ops->update_san_info)
                                hsr->proto_ops->update_san_info(node, is_sup);
                        return node;
                }
        }

        /* Check if required node is not in proxy nodes table */
        list_for_each_entry_rcu(node, &hsr->proxy_node_db, mac_list) {
                if (ether_addr_equal(node->macaddress_A, ethhdr->h_source)) {
                        if (hsr->proto_ops->update_san_info)
                                hsr->proto_ops->update_san_info(node, is_sup);
                        return node;
                }
        }

        /* Everyone may create a node entry, connected node to a HSR/PRP
         * device.
         */
        if (ethhdr->h_proto == htons(ETH_P_PRP) ||
            ethhdr->h_proto == htons(ETH_P_HSR)) {
                /* Check if skb contains hsr_ethhdr */
                if (skb->mac_len < sizeof(struct hsr_ethhdr))
                        return NULL;
        } else {
                rct = skb_get_PRP_rct(skb);
                if (!rct && rx_port != HSR_PT_MASTER)
                        san = true;
        }

        return hsr_add_node(hsr, node_db, ethhdr->h_source, san, rx_port);
}

static bool hsr_seq_block_is_old(struct hsr_seq_block *block)
{
        unsigned long expiry = msecs_to_jiffies(HSR_ENTRY_FORGET_TIME);

        return time_is_before_jiffies(block->time + expiry);
}

static void hsr_forget_seq_block(struct hsr_node *node,
                                 struct hsr_seq_block *block)
{
        if (block->time)
                xa_erase(&node->seq_blocks, block->block_idx);
        block->time = 0;
}

/* Get the currently active sequence number block. If there is no block yet, or
 * the existing one is expired, a new block is created. The idea is to maintain
 * a "sparse bitmap" where a bitmap for the whole sequence number space is
 * split into blocks and not all blocks exist all the time. The blocks can
 * expire after time (in low traffic situations) or when they are replaced in
 * the backing fixed size buffer (in high traffic situations).
 */
VISIBLE_IF_KUNIT struct hsr_seq_block *hsr_get_seq_block(struct hsr_node *node,
                                                         u16 block_idx)
{
        struct hsr_seq_block *block, *res;
        size_t block_sz;

        block = xa_load(&node->seq_blocks, block_idx);

        if (block && hsr_seq_block_is_old(block)) {
                hsr_forget_seq_block(node, block);
                block = NULL;
        }

        if (!block) {
                block_sz = hsr_seq_block_size(node);
                block = node->block_buf + node->next_block * block_sz;
                hsr_forget_seq_block(node, block);

                memset(block, 0, block_sz);
                block->time = jiffies;
                block->block_idx = block_idx;

                res = xa_store(&node->seq_blocks, block_idx, block, GFP_ATOMIC);
                if (xa_is_err(res)) {
                        block->time = 0;
                        return NULL;
                }

                node->next_block =
                        (node->next_block + 1) & (HSR_MAX_SEQ_BLOCKS - 1);
        }

        return block;
}
EXPORT_SYMBOL_IF_KUNIT(hsr_get_seq_block);

/* Use the Supervision frame's info about an eventual macaddress_B for merging
 * nodes that has previously had their macaddress_B registered as a separate
 * node.
 */
void hsr_handle_sup_frame(struct hsr_frame_info *frame)
{
        struct hsr_node *node_curr = frame->node_src;
        struct hsr_port *port_rcv = frame->port_rcv;
        struct hsr_seq_block *src_blk, *merge_blk;
        struct hsr_priv *hsr = port_rcv->hsr;
        struct hsr_sup_tlv *hsr_sup_tlv;
        struct hsr_sup_payload *hsr_sp;
        struct hsr_node *node_real;
        struct sk_buff *skb = NULL;
        struct list_head *node_db;
        struct ethhdr *ethhdr;
        unsigned int total_pull_size = 0;
        unsigned int pull_size = 0;
        unsigned long idx;
        int i;

        /* Here either frame->skb_hsr or frame->skb_prp should be
         * valid as supervision frame always will have protocol
         * header info.
         */
        if (frame->skb_hsr)
                skb = frame->skb_hsr;
        else if (frame->skb_prp)
                skb = frame->skb_prp;
        else if (frame->skb_std)
                skb = frame->skb_std;
        if (!skb)
                return;

        /* Leave the ethernet header. */
        pull_size = sizeof(struct ethhdr);
        skb_pull(skb, pull_size);
        total_pull_size += pull_size;

        ethhdr = (struct ethhdr *)skb_mac_header(skb);

        /* And leave the HSR tag. */
        if (ethhdr->h_proto == htons(ETH_P_HSR)) {
                pull_size = sizeof(struct hsr_tag);
                skb_pull(skb, pull_size);
                total_pull_size += pull_size;
        }

        /* And leave the HSR sup tag. */
        pull_size = sizeof(struct hsr_sup_tag);
        skb_pull(skb, pull_size);
        total_pull_size += pull_size;

        /* get HSR sup payload */
        hsr_sp = (struct hsr_sup_payload *)skb->data;

        /* Merge node_curr (registered on macaddress_B) into node_real */
        node_db = &port_rcv->hsr->node_db;
        node_real = find_node_by_addr_A(node_db, hsr_sp->macaddress_A);
        if (!node_real)
                /* No frame received from AddrA of this node yet */
                node_real = hsr_add_node(hsr, node_db, hsr_sp->macaddress_A,
                                         true, port_rcv->type);
        if (!node_real)
                goto done; /* No mem */
        if (node_real == node_curr)
                /* Node has already been merged */
                goto done;

        /* Leave the first HSR sup payload. */
        pull_size = sizeof(struct hsr_sup_payload);
        skb_pull(skb, pull_size);
        total_pull_size += pull_size;

        /* Get second supervision tlv */
        hsr_sup_tlv = (struct hsr_sup_tlv *)skb->data;
        /* And check if it is a redbox mac TLV */
        if (hsr_sup_tlv->HSR_TLV_type == PRP_TLV_REDBOX_MAC) {
                /* We could stop here after pushing hsr_sup_payload,
                 * or proceed and allow macaddress_B and for redboxes.
                 */
                /* Sanity check length */
                if (hsr_sup_tlv->HSR_TLV_length != 6)
                        goto done;

                /* Leave the second HSR sup tlv. */
                pull_size = sizeof(struct hsr_sup_tlv);
                skb_pull(skb, pull_size);
                total_pull_size += pull_size;

                /* Get redbox mac address. */
                hsr_sp = (struct hsr_sup_payload *)skb->data;

                /* Check if redbox mac and node mac are equal. */
                if (!ether_addr_equal(node_real->macaddress_A, hsr_sp->macaddress_A)) {
                        /* This is a redbox supervision frame for a VDAN! */
                        goto done;
                }
        }

        ether_addr_copy(node_real->macaddress_B, ethhdr->h_source);
        hsr_lock_seq_out_pair(node_real, node_curr);
        for (i = 0; i < HSR_PT_PORTS; i++) {
                if (!node_curr->time_in_stale[i] &&
                    time_after(node_curr->time_in[i], node_real->time_in[i])) {
                        node_real->time_in[i] = node_curr->time_in[i];
                        node_real->time_in_stale[i] =
                                                node_curr->time_in_stale[i];
                }
        }

        xa_for_each(&node_curr->seq_blocks, idx, src_blk) {
                if (hsr_seq_block_is_old(src_blk))
                        continue;

                merge_blk = hsr_get_seq_block(node_real, src_blk->block_idx);
                if (!merge_blk)
                        continue;
                merge_blk->time = min(merge_blk->time, src_blk->time);
                for (i = 0; i < node_real->seq_port_cnt; i++) {
                        bitmap_or(merge_blk->seq_nrs[i], merge_blk->seq_nrs[i],
                                  src_blk->seq_nrs[i], HSR_SEQ_BLOCK_SIZE);
                }
        }
        hsr_unlock_seq_out_pair(node_real, node_curr);
        node_real->addr_B_port = port_rcv->type;

        spin_lock_bh(&hsr->list_lock);
        if (!node_curr->removed) {
                list_del_rcu(&node_curr->mac_list);
                node_curr->removed = true;
                call_rcu(&node_curr->rcu_head, hsr_free_node_rcu);
        }
        spin_unlock_bh(&hsr->list_lock);

done:
        /* Push back here */
        skb_push(skb, total_pull_size);
}

/* 'skb' is a frame meant for this host, that is to be passed to upper layers.
 *
 * If the frame was sent by a node's B interface, replace the source
 * address with that node's "official" address (macaddress_A) so that upper
 * layers recognize where it came from.
 */
void hsr_addr_subst_source(struct hsr_node *node, struct sk_buff *skb)
{
        if (!skb_mac_header_was_set(skb)) {
                WARN_ONCE(1, "%s: Mac header not set\n", __func__);
                return;
        }

        memcpy(&eth_hdr(skb)->h_source, node->macaddress_A, ETH_ALEN);
}

/* 'skb' is a frame meant for another host.
 * 'port' is the outgoing interface
 *
 * Substitute the target (dest) MAC address if necessary, so the it matches the
 * recipient interface MAC address, regardless of whether that is the
 * recipient's A or B interface.
 * This is needed to keep the packets flowing through switches that learn on
 * which "side" the different interfaces are.
 */
void hsr_addr_subst_dest(struct hsr_node *node_src, struct sk_buff *skb,
                         struct hsr_port *port)
{
        struct hsr_node *node_dst;

        if (!skb_mac_header_was_set(skb)) {
                WARN_ONCE(1, "%s: Mac header not set\n", __func__);
                return;
        }

        if (!is_unicast_ether_addr(eth_hdr(skb)->h_dest))
                return;

        node_dst = find_node_by_addr_A(&port->hsr->node_db,
                                       eth_hdr(skb)->h_dest);
        if (!node_dst && port->hsr->redbox)
                node_dst = find_node_by_addr_A(&port->hsr->proxy_node_db,
                                               eth_hdr(skb)->h_dest);

        if (!node_dst) {
                if (port->hsr->prot_version != PRP_V1 && net_ratelimit())
                        netdev_err(skb->dev, "%s: Unknown node\n", __func__);
                return;
        }
        if (port->type != node_dst->addr_B_port)
                return;

        if (is_valid_ether_addr(node_dst->macaddress_B))
                ether_addr_copy(eth_hdr(skb)->h_dest, node_dst->macaddress_B);
}

void hsr_register_frame_in(struct hsr_node *node, struct hsr_port *port,
                           u16 sequence_nr)
{
        node->time_in[port->type] = jiffies;
        node->time_in_stale[port->type] = false;
}

/* Duplicate discard algorithm: we maintain a bitmap where we set a bit for
 * every seen sequence number. The bitmap is split into blocks and the block
 * management is detailed in hsr_get_seq_block(). In any case, we err on the
 * side of accepting a packet, as the specification requires the algorithm to
 * be "designed such that it never rejects a legitimate frame, while occasional
 * acceptance of a duplicate can be tolerated." (IEC 62439-3:2021, 4.1.10.3).
 * While this requirement is explicit for PRP, applying it to HSR does no harm
 * either.
 *
 * 'frame' is the frame to be sent
 * 'port_type' is the type of the outgoing interface
 *
 * Return:
 *       1 if frame can be shown to have been sent recently on this interface,
 *       0 otherwise
 */
static int hsr_check_duplicate(struct hsr_frame_info *frame,
                               unsigned int port_type)
{
        u16 sequence_nr, seq_bit, block_idx;
        struct hsr_seq_block *block;
        struct hsr_node *node;

        node = frame->node_src;
        sequence_nr = frame->sequence_nr;

        if (WARN_ON_ONCE(port_type >= node->seq_port_cnt))
                return 0;

        spin_lock_bh(&node->seq_out_lock);

        block_idx = hsr_seq_block_index(sequence_nr);
        block = hsr_get_seq_block(node, block_idx);
        if (!block)
                goto out_new;

        seq_bit = hsr_seq_block_bit(sequence_nr);
        if (__test_and_set_bit(seq_bit, block->seq_nrs[port_type]))
                goto out_seen;

out_new:
        spin_unlock_bh(&node->seq_out_lock);
        return 0;

out_seen:
        spin_unlock_bh(&node->seq_out_lock);
        return 1;
}

/* HSR duplicate discard: we check if the same frame has already been sent on
 * this outgoing interface. The check follows the general duplicate discard
 * algorithm.
 *
 * 'port' is the outgoing interface
 * 'frame' is the frame to be sent
 *
 * Return:
 *       1 if frame can be shown to have been sent recently on this interface,
 *       0 otherwise
 */
int hsr_register_frame_out(struct hsr_port *port, struct hsr_frame_info *frame)
{
        return hsr_check_duplicate(frame, port->type - 1);
}

/* PRP duplicate discard: we only consider frames that are received on port A
 * or port B and should go to the master port. For those, we check if they have
 * already been received by the host, i.e., master port. The check uses the
 * general duplicate discard algorithm, but without tracking multiple ports.
 *
 * 'port' is the outgoing interface
 * 'frame' is the frame to be sent
 *
 * Return:
 *       1 if frame can be shown to have been sent recently on this interface,
 *       0 otherwise
 */
int prp_register_frame_out(struct hsr_port *port, struct hsr_frame_info *frame)
{
        /* out-going frames are always in order */
        if (frame->port_rcv->type == HSR_PT_MASTER)
                return 0;

        /* for PRP we should only forward frames from the slave ports
         * to the master port
         */
        if (port->type != HSR_PT_MASTER)
                return 1;

        return hsr_check_duplicate(frame, 0);
}
EXPORT_SYMBOL_IF_KUNIT(prp_register_frame_out);

static struct hsr_port *get_late_port(struct hsr_priv *hsr,
                                      struct hsr_node *node)
{
        if (node->time_in_stale[HSR_PT_SLAVE_A])
                return hsr_port_get_hsr(hsr, HSR_PT_SLAVE_A);
        if (node->time_in_stale[HSR_PT_SLAVE_B])
                return hsr_port_get_hsr(hsr, HSR_PT_SLAVE_B);

        if (time_after(node->time_in[HSR_PT_SLAVE_B],
                       node->time_in[HSR_PT_SLAVE_A] +
                                        msecs_to_jiffies(MAX_SLAVE_DIFF)))
                return hsr_port_get_hsr(hsr, HSR_PT_SLAVE_A);
        if (time_after(node->time_in[HSR_PT_SLAVE_A],
                       node->time_in[HSR_PT_SLAVE_B] +
                                        msecs_to_jiffies(MAX_SLAVE_DIFF)))
                return hsr_port_get_hsr(hsr, HSR_PT_SLAVE_B);

        return NULL;
}

/* Remove stale sequence_nr records. Called by timer every
 * HSR_LIFE_CHECK_INTERVAL (two seconds or so).
 */
void hsr_prune_nodes(struct timer_list *t)
{
        struct hsr_priv *hsr = timer_container_of(hsr, t, prune_timer);
        struct hsr_node *node;
        struct hsr_node *tmp;
        struct hsr_port *port;
        unsigned long timestamp;
        unsigned long time_a, time_b;

        spin_lock_bh(&hsr->list_lock);
        list_for_each_entry_safe(node, tmp, &hsr->node_db, mac_list) {
                /* Don't prune own node. Neither time_in[HSR_PT_SLAVE_A]
                 * nor time_in[HSR_PT_SLAVE_B], will ever be updated for
                 * the master port. Thus the master node will be repeatedly
                 * pruned leading to packet loss.
                 */
                if (hsr_addr_is_self(hsr, node->macaddress_A))
                        continue;

                /* Shorthand */
                time_a = node->time_in[HSR_PT_SLAVE_A];
                time_b = node->time_in[HSR_PT_SLAVE_B];

                /* Check for timestamps old enough to risk wrap-around */
                if (time_after(jiffies, time_a + MAX_JIFFY_OFFSET / 2))
                        node->time_in_stale[HSR_PT_SLAVE_A] = true;
                if (time_after(jiffies, time_b + MAX_JIFFY_OFFSET / 2))
                        node->time_in_stale[HSR_PT_SLAVE_B] = true;

                /* Get age of newest frame from node.
                 * At least one time_in is OK here; nodes get pruned long
                 * before both time_ins can get stale
                 */
                timestamp = time_a;
                if (node->time_in_stale[HSR_PT_SLAVE_A] ||
                    (!node->time_in_stale[HSR_PT_SLAVE_B] &&
                    time_after(time_b, time_a)))
                        timestamp = time_b;

                /* Warn of ring error only as long as we get frames at all */
                if (time_is_after_jiffies(timestamp +
                                msecs_to_jiffies(1.5 * MAX_SLAVE_DIFF))) {
                        rcu_read_lock();
                        port = get_late_port(hsr, node);
                        if (port)
                                hsr_nl_ringerror(hsr, node->macaddress_A, port);
                        rcu_read_unlock();
                }

                /* Prune old entries */
                if (time_is_before_jiffies(timestamp +
                                msecs_to_jiffies(HSR_NODE_FORGET_TIME))) {
                        hsr_nl_nodedown(hsr, node->macaddress_A);
                        if (!node->removed) {
                                list_del_rcu(&node->mac_list);
                                node->removed = true;
                                /* Note that we need to free this entry later: */
                                call_rcu(&node->rcu_head, hsr_free_node_rcu);
                        }
                }
        }
        spin_unlock_bh(&hsr->list_lock);

        /* Restart timer */
        mod_timer(&hsr->prune_timer,
                  jiffies + msecs_to_jiffies(PRUNE_PERIOD));
}

void hsr_prune_proxy_nodes(struct timer_list *t)
{
        struct hsr_priv *hsr = timer_container_of(hsr, t, prune_proxy_timer);
        unsigned long timestamp;
        struct hsr_node *node;
        struct hsr_node *tmp;

        spin_lock_bh(&hsr->list_lock);
        list_for_each_entry_safe(node, tmp, &hsr->proxy_node_db, mac_list) {
                /* Don't prune RedBox node. */
                if (hsr_addr_is_redbox(hsr, node->macaddress_A))
                        continue;

                timestamp = node->time_in[HSR_PT_INTERLINK];

                /* Prune old entries */
                if (time_is_before_jiffies(timestamp +
                                msecs_to_jiffies(HSR_PROXY_NODE_FORGET_TIME))) {
                        hsr_nl_nodedown(hsr, node->macaddress_A);
                        if (!node->removed) {
                                list_del_rcu(&node->mac_list);
                                node->removed = true;
                                /* Note that we need to free this entry later: */
                                call_rcu(&node->rcu_head, hsr_free_node_rcu);
                        }
                }
        }

        spin_unlock_bh(&hsr->list_lock);

        /* Restart timer */
        mod_timer(&hsr->prune_proxy_timer,
                  jiffies + msecs_to_jiffies(PRUNE_PROXY_PERIOD));
}

void *hsr_get_next_node(struct hsr_priv *hsr, void *_pos,
                        unsigned char addr[ETH_ALEN])
{
        struct hsr_node *node;

        if (!_pos) {
                node = list_first_or_null_rcu(&hsr->node_db,
                                              struct hsr_node, mac_list);
                if (node)
                        ether_addr_copy(addr, node->macaddress_A);
                return node;
        }

        node = _pos;
        list_for_each_entry_continue_rcu(node, &hsr->node_db, mac_list) {
                ether_addr_copy(addr, node->macaddress_A);
                return node;
        }

        return NULL;
}

/* Fill the last sequence number that has been received from node on if1 by
 * finding the last sequence number sent on port B; accordingly get the last
 * received sequence number for if2 using sent sequence numbers on port A.
 */
static void fill_last_seq_nrs(struct hsr_node *node, u16 *if1_seq, u16 *if2_seq)
{
        struct hsr_seq_block *block;
        unsigned int block_off;
        size_t block_sz;
        u16 seq_bit;

        spin_lock_bh(&node->seq_out_lock);

        /* Get last inserted block */
        block_off = (node->next_block - 1) & (HSR_MAX_SEQ_BLOCKS - 1);
        block_sz = hsr_seq_block_size(node);
        block = node->block_buf + block_off * block_sz;

        if (!bitmap_empty(block->seq_nrs[HSR_PT_SLAVE_B - 1],
                          HSR_SEQ_BLOCK_SIZE)) {
                seq_bit = find_last_bit(block->seq_nrs[HSR_PT_SLAVE_B - 1],
                                        HSR_SEQ_BLOCK_SIZE);
                *if1_seq = (block->block_idx << HSR_SEQ_BLOCK_SHIFT) | seq_bit;
        }
        if (!bitmap_empty(block->seq_nrs[HSR_PT_SLAVE_A - 1],
                          HSR_SEQ_BLOCK_SIZE)) {
                seq_bit = find_last_bit(block->seq_nrs[HSR_PT_SLAVE_A - 1],
                                        HSR_SEQ_BLOCK_SIZE);
                *if2_seq = (block->block_idx << HSR_SEQ_BLOCK_SHIFT) | seq_bit;
        }
        spin_unlock_bh(&node->seq_out_lock);
}

int hsr_get_node_data(struct hsr_priv *hsr,
                      const unsigned char *addr,
                      unsigned char addr_b[ETH_ALEN],
                      unsigned int *addr_b_ifindex,
                      int *if1_age,
                      u16 *if1_seq,
                      int *if2_age,
                      u16 *if2_seq)
{
        struct hsr_node *node;
        struct hsr_port *port;
        unsigned long tdiff;

        node = find_node_by_addr_A(&hsr->node_db, addr);
        if (!node)
                return -ENOENT;

        ether_addr_copy(addr_b, node->macaddress_B);

        tdiff = jiffies - node->time_in[HSR_PT_SLAVE_A];
        if (node->time_in_stale[HSR_PT_SLAVE_A])
                *if1_age = INT_MAX;
#if HZ <= MSEC_PER_SEC
        else if (tdiff > msecs_to_jiffies(INT_MAX))
                *if1_age = INT_MAX;
#endif
        else
                *if1_age = jiffies_to_msecs(tdiff);

        tdiff = jiffies - node->time_in[HSR_PT_SLAVE_B];
        if (node->time_in_stale[HSR_PT_SLAVE_B])
                *if2_age = INT_MAX;
#if HZ <= MSEC_PER_SEC
        else if (tdiff > msecs_to_jiffies(INT_MAX))
                *if2_age = INT_MAX;
#endif
        else
                *if2_age = jiffies_to_msecs(tdiff);

        /* Present sequence numbers as if they were incoming on interface */
        *if1_seq = 0;
        *if2_seq = 0;
        if (hsr->prot_version != PRP_V1)
                fill_last_seq_nrs(node, if1_seq, if2_seq);

        if (node->addr_B_port != HSR_PT_NONE) {
                port = hsr_port_get_hsr(hsr, node->addr_B_port);
                *addr_b_ifindex = port->dev->ifindex;
        } else {
                *addr_b_ifindex = -1;
        }

        return 0;
}