net/hsr: Use list_head (and rcu) instead of array for slave devices.

[deliverable/linux.git] / net / hsr / hsr_framereg.c

/* Copyright 2011-2014 Autronica Fire and Security AS
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the Free
 * Software Foundation; either version 2 of the License, or (at your option)
 * any later version.
 *
 * 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.
 */

#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"


struct hsr_node {
        struct list_head        mac_list;
        unsigned char           MacAddressA[ETH_ALEN];
        unsigned char           MacAddressB[ETH_ALEN];
        /* Local slave through which AddrB frames are received from this node */
        enum hsr_port_type      AddrB_port;
        unsigned long           time_in[HSR_PT_PORTS];
        bool                    time_in_stale[HSR_PT_PORTS];
        u16                     seq_out[HSR_PT_PORTS];
        struct rcu_head         rcu_head;
};

/*      TODO: use hash lists for mac addresses (linux/jhash.h)?    */



/* Search for mac entry. Caller must hold rcu read lock.
 */
static struct hsr_node *find_node_by_AddrA(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->MacAddressA, addr))
                        return node;
        }

        return NULL;
}


/* Search for mac entry. Caller must hold rcu read lock.
 */
static struct hsr_node *find_node_by_AddrB(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->MacAddressB, addr))
                        return node;
        }

        return NULL;
}


/* Search for mac entry. Caller must hold rcu read lock.
 */
struct hsr_node *hsr_find_node(struct list_head *node_db, struct sk_buff *skb)
{
        struct hsr_node *node;
        struct ethhdr *ethhdr;

        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->MacAddressA, ethhdr->h_source))
                        return node;
                if (ether_addr_equal(node->MacAddressB, ethhdr->h_source))
                        return node;
        }

        return NULL;
}


/* Helper for device init; the self_node_db is used in hsr_rcv() to recognize
 * frames from self that's been looped over the HSR ring.
 */
int hsr_create_self_node(struct list_head *self_node_db,
                         unsigned char addr_a[ETH_ALEN],
                         unsigned char addr_b[ETH_ALEN])
{
        struct hsr_node *node, *oldnode;

        node = kmalloc(sizeof(*node), GFP_KERNEL);
        if (!node)
                return -ENOMEM;

        ether_addr_copy(node->MacAddressA, addr_a);
        ether_addr_copy(node->MacAddressB, addr_b);

        rcu_read_lock();
        oldnode = list_first_or_null_rcu(self_node_db,
                                                struct hsr_node, mac_list);
        if (oldnode) {
                list_replace_rcu(&oldnode->mac_list, &node->mac_list);
                rcu_read_unlock();
                synchronize_rcu();
                kfree(oldnode);
        } else {
                rcu_read_unlock();
                list_add_tail_rcu(&node->mac_list, self_node_db);
        }

        return 0;
}


/* Add/merge node to the database of nodes. 'skb' must contain an HSR
 * supervision frame.
 * - If the supervision header's MacAddressA field is not yet in the database,
 * this frame is from an hitherto unknown node - add it to the database.
 * - If the sender's MAC address is not the same as its MacAddressA address,
 * the node is using PICS_SUBS (address substitution). Record the sender's
 * address as the node's MacAddressB.
 *
 * This function needs to work even if the sender node has changed one of its
 * slaves' MAC addresses. In this case, there are four different cases described
 * by (Addr-changed, received-from) pairs as follows. Note that changing the
 * SlaveA address is equal to changing the node's own address:
 *
 * - (AddrB, SlaveB): The new AddrB will be recorded by PICS_SUBS code since
 *                    node == NULL.
 * - (AddrB, SlaveA): Will work as usual (the AddrB change won't be detected
 *                    from this frame).
 *
 * - (AddrA, SlaveB): The old node will be found. We need to detect this and
 *                    remove the node.
 * - (AddrA, SlaveA): A new node will be registered (non-PICS_SUBS at first).
 *                    The old one will be pruned after HSR_NODE_FORGET_TIME.
 *
 * We also need to detect if the sender's SlaveA and SlaveB cables have been
 * swapped.
 */
struct hsr_node *hsr_merge_node(struct hsr_node *node, struct sk_buff *skb,
                                struct hsr_port *port)
{
        struct hsr_priv *hsr;
        struct hsr_sup_payload *hsr_sp;
        struct hsr_ethhdr_sp *hsr_ethsup;
        int i;
        unsigned long now;

        hsr_ethsup = (struct hsr_ethhdr_sp *) skb_mac_header(skb);
        hsr_sp = (struct hsr_sup_payload *) skb->data;
        hsr = port->hsr;

        if (node && !ether_addr_equal(node->MacAddressA, hsr_sp->MacAddressA)) {
                /* Node has changed its AddrA, frame was received from SlaveB */
                list_del_rcu(&node->mac_list);
                kfree_rcu(node, rcu_head);
                node = NULL;
        }

        if (node && (port->type == node->AddrB_port) &&
            !ether_addr_equal(node->MacAddressB, hsr_ethsup->ethhdr.h_source)) {
                /* Cables have been swapped */
                list_del_rcu(&node->mac_list);
                kfree_rcu(node, rcu_head);
                node = NULL;
        }

        if (node && (port->type != node->AddrB_port) &&
            (node->AddrB_port != HSR_PT_NONE) &&
            !ether_addr_equal(node->MacAddressA, hsr_ethsup->ethhdr.h_source)) {
                /* Cables have been swapped */
                list_del_rcu(&node->mac_list);
                kfree_rcu(node, rcu_head);
                node = NULL;
        }

        if (node)
                return node;

        node = find_node_by_AddrA(&hsr->node_db, hsr_sp->MacAddressA);
        if (node) {
                /* Node is known, but frame was received from an unknown
                 * address. Node is PICS_SUBS capable; merge its AddrB.
                 */
                ether_addr_copy(node->MacAddressB, hsr_ethsup->ethhdr.h_source);
                node->AddrB_port = port->type;
                return node;
        }

        node = kzalloc(sizeof(*node), GFP_ATOMIC);
        if (!node)
                return NULL;

        ether_addr_copy(node->MacAddressA, hsr_sp->MacAddressA);
        ether_addr_copy(node->MacAddressB, hsr_ethsup->ethhdr.h_source);
        if (!ether_addr_equal(hsr_sp->MacAddressA, hsr_ethsup->ethhdr.h_source))
                node->AddrB_port = port->type;

        /* 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++)
                node->time_in[i] = now;
        for (i = 0; i < HSR_PT_PORTS; i++)
                node->seq_out[i] = ntohs(hsr_ethsup->hsr_sup.sequence_nr) - 1;

        list_add_tail_rcu(&node->mac_list, &hsr->node_db);

        return node;
}


/* '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 sender
 * address with that node's "official" address (MacAddressA) so that upper
 * layers recognize where it came from.
 */
void hsr_addr_subst_source(struct hsr_priv *hsr, struct sk_buff *skb)
{
        struct ethhdr *ethhdr;
        struct hsr_node *node;

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

        rcu_read_lock();
        node = find_node_by_AddrB(&hsr->node_db, ethhdr->h_source);
        if (node)
                ether_addr_copy(ethhdr->h_source, node->MacAddressA);
        rcu_read_unlock();
}


/* 'skb' is a frame meant for another host.
 * 'hsr_dev_idx' is the HSR index of the outgoing device
 *
 * 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_priv *hsr, struct ethhdr *ethhdr,
                         struct hsr_port *port)
{
        struct hsr_node *node;

        rcu_read_lock();
        node = find_node_by_AddrA(&hsr->node_db, ethhdr->h_dest);
        if (node && (node->AddrB_port == port->type))
                ether_addr_copy(ethhdr->h_dest, node->MacAddressB);
        rcu_read_unlock();
}


/* seq_nr_after(a, b) - return true if a is after (higher in sequence than) b,
 * false otherwise.
 */
static bool seq_nr_after(u16 a, u16 b)
{
        /* Remove inconsistency where
         * seq_nr_after(a, b) == seq_nr_before(a, b)
         */
        if ((int) b - a == 32768)
                return false;

        return (((s16) (b - a)) < 0);
}
#define seq_nr_before(a, b)             seq_nr_after((b), (a))
#define seq_nr_after_or_eq(a, b)        (!seq_nr_before((a), (b)))
#define seq_nr_before_or_eq(a, b)       (!seq_nr_after((a), (b)))


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


/* 'skb' is a HSR Ethernet frame (with a HSR tag inserted), with a valid
 * ethhdr->h_source address and skb->mac_header set.
 *
 * Return:
 *       1 if frame can be shown to have been sent recently on this interface,
 *       0 otherwise, or
 *       negative error code on error
 */
int hsr_register_frame_out(struct hsr_node *node, struct hsr_port *port,
                           struct sk_buff *skb)
{
        struct hsr_ethhdr *hsr_ethhdr;
        u16 sequence_nr;

        if (!skb_mac_header_was_set(skb)) {
                WARN_ONCE(1, "%s: Mac header not set\n", __func__);
                return -EINVAL;
        }
        hsr_ethhdr = (struct hsr_ethhdr *) skb_mac_header(skb);

        sequence_nr = ntohs(hsr_ethhdr->hsr_tag.sequence_nr);
        if (seq_nr_before_or_eq(sequence_nr, node->seq_out[port->type]))
                return 1;

        node->seq_out[port->type] = sequence_nr;
        return 0;
}


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(unsigned long data)
{
        struct hsr_priv *hsr;
        struct hsr_node *node;
        struct hsr_port *port;
        unsigned long timestamp;
        unsigned long time_a, time_b;

        hsr = (struct hsr_priv *) data;

        rcu_read_lock();
        list_for_each_entry_rcu(node, &hsr->node_db, mac_list) {
                /* 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 != NULL)
                                hsr_nl_ringerror(hsr, node->MacAddressA, 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->MacAddressA);
                        list_del_rcu(&node->mac_list);
                        /* Note that we need to free this entry later: */
                        kfree_rcu(node, rcu_head);
                }
        }
        rcu_read_unlock();
}


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->MacAddressA);
                return node;
        }

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

        return NULL;
}


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;


        rcu_read_lock();
        node = find_node_by_AddrA(&hsr->node_db, addr);
        if (!node) {
                rcu_read_unlock();
                return -ENOENT; /* No such entry */
        }

        ether_addr_copy(addr_b, node->MacAddressB);

        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 = node->seq_out[HSR_PT_SLAVE_B];
        *if2_seq = node->seq_out[HSR_PT_SLAVE_A];

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

        rcu_read_unlock();

        return 0;
}