l2t.c

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/*
 * This file is part of the Chelsio T4 Ethernet driver for Linux.
 *
 * Copyright (c) 2003-2010 Chelsio Communications, Inc. All rights reserved.
 *
 * This software is available to you under a choice of one of two
 * licenses.  You may choose to be licensed under the terms of the GNU
 * General Public License (GPL) Version 2, available from the file
 * COPYING in the main directory of this source tree, or the
 * OpenIB.org BSD license below:
 *
 *     Redistribution and use in source and binary forms, with or
 *     without modification, are permitted provided that the following
 *     conditions are met:
 *
 *      - Redistributions of source code must retain the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer.
 *
 *      - Redistributions in binary form must reproduce the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer in the documentation and/or other materials
 *        provided with the distribution.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

#include <linux/skbuff.h>
#include <linux/netdevice.h>
#include <linux/if.h>
#include <linux/if_vlan.h>
#include <linux/jhash.h>
#include <linux/module.h>
#include <linux/debugfs.h>
#include <linux/seq_file.h>
#include <net/neighbour.h>
#include "cxgb4.h"
#include "l2t.h"
#include "t4_msg.h"
#include "t4fw_api.h"

#define VLAN_NONE 0xfff

/* identifies sync vs async L2T_WRITE_REQs */
#define F_SYNC_WR    (1 << 12)

enum {
    L2T_STATE_VALID,      /* entry is up to date */
    L2T_STATE_STALE,      /* entry may be used but needs revalidation */
    L2T_STATE_RESOLVING,  /* entry needs address resolution */
    L2T_STATE_SYNC_WRITE, /* synchronous write of entry underway */

    /* when state is one of the below the entry is not hashed */
    L2T_STATE_SWITCHING,  /* entry is being used by a switching filter */
    L2T_STATE_UNUSED      /* entry not in use */
};

struct l2t_data {
    rwlock_t lock;
    atomic_t nfree;             /* number of free entries */
    struct l2t_entry *rover;    /* starting point for next allocation */
    struct l2t_entry l2tab[L2T_SIZE];
};

static inline unsigned int vlan_prio(const struct l2t_entry *e)
{
    return e->vlan >> 13;
}

static inline void l2t_hold(struct l2t_data *d, struct l2t_entry *e)
{
    if (atomic_add_return(1, &e->refcnt) == 1)  /* 0 -> 1 transition */
        atomic_dec(&d->nfree);
}

/*
 * To avoid having to check address families we do not allow v4 and v6
 * neighbors to be on the same hash chain.  We keep v4 entries in the first
 * half of available hash buckets and v6 in the second.
 */
enum {
    L2T_SZ_HALF = L2T_SIZE / 2,
    L2T_HASH_MASK = L2T_SZ_HALF - 1
};

static inline unsigned int arp_hash(const u32 *key, int ifindex)
{
    return jhash_2words(*key, ifindex, 0) & L2T_HASH_MASK;
}

static inline unsigned int ipv6_hash(const u32 *key, int ifindex)
{
    u32 xor = key[0] ^ key[1] ^ key[2] ^ key[3];

    return L2T_SZ_HALF + (jhash_2words(xor, ifindex, 0) & L2T_HASH_MASK);
}

static unsigned int addr_hash(const u32 *addr, int addr_len, int ifindex)
{
    return addr_len == 4 ? arp_hash(addr, ifindex) :
                   ipv6_hash(addr, ifindex);
}

/*
 * Checks if an L2T entry is for the given IP/IPv6 address.  It does not check
 * whether the L2T entry and the address are of the same address family.
 * Callers ensure an address is only checked against L2T entries of the same
 * family, something made trivial by the separation of IP and IPv6 hash chains
 * mentioned above.  Returns 0 if there's a match,
 */
static int addreq(const struct l2t_entry *e, const u32 *addr)
{
    if (e->v6)
        return (e->addr[0] ^ addr[0]) | (e->addr[1] ^ addr[1]) |
               (e->addr[2] ^ addr[2]) | (e->addr[3] ^ addr[3]);
    return e->addr[0] ^ addr[0];
}

static void neigh_replace(struct l2t_entry *e, struct neighbour *n)
{
    neigh_hold(n);
    if (e->neigh)
        neigh_release(e->neigh);
    e->neigh = n;
}

/*
 * Write an L2T entry.  Must be called with the entry locked.
 * The write may be synchronous or asynchronous.
 */
static int write_l2e(struct adapter *adap, struct l2t_entry *e, int sync)
{
    struct sk_buff *skb;
    struct cpl_l2t_write_req *req;

    skb = alloc_skb(sizeof(*req), GFP_ATOMIC);
    if (!skb)
        return -ENOMEM;

    req = (struct cpl_l2t_write_req *)__skb_put(skb, sizeof(*req));
    INIT_TP_WR(req, 0);

    OPCODE_TID(req) = htonl(MK_OPCODE_TID(CPL_L2T_WRITE_REQ,
                    e->idx | (sync ? F_SYNC_WR : 0) |
                    TID_QID(adap->sge.fw_evtq.abs_id)));
    req->params = htons(L2T_W_PORT(e->lport) | L2T_W_NOREPLY(!sync));
    req->l2t_idx = htons(e->idx);
    req->vlan = htons(e->vlan);
    if (e->neigh)
        memcpy(e->dmac, e->neigh->ha, sizeof(e->dmac));
    memcpy(req->dst_mac, e->dmac, sizeof(req->dst_mac));

    set_wr_txq(skb, CPL_PRIORITY_CONTROL, 0);
    t4_ofld_send(adap, skb);

    if (sync && e->state != L2T_STATE_SWITCHING)
        e->state = L2T_STATE_SYNC_WRITE;
    return 0;
}

/*
 * Send packets waiting in an L2T entry's ARP queue.  Must be called with the
 * entry locked.
 */
static void send_pending(struct adapter *adap, struct l2t_entry *e)
{
    while (e->arpq_head) {
        struct sk_buff *skb = e->arpq_head;

        e->arpq_head = skb->next;
        skb->next = NULL;
        t4_ofld_send(adap, skb);
    }
    e->arpq_tail = NULL;
}

/*
 * Process a CPL_L2T_WRITE_RPL.  Wake up the ARP queue if it completes a
 * synchronous L2T_WRITE.  Note that the TID in the reply is really the L2T
 * index it refers to.
 */
void do_l2t_write_rpl(struct adapter *adap, const struct cpl_l2t_write_rpl *rpl)
{
    unsigned int tid = GET_TID(rpl);
    unsigned int idx = tid & (L2T_SIZE - 1);

    if (unlikely(rpl->status != CPL_ERR_NONE)) {
        dev_err(adap->pdev_dev,
            "Unexpected L2T_WRITE_RPL status %u for entry %u\n",
            rpl->status, idx);
        return;
    }

    if (tid & F_SYNC_WR) {
        struct l2t_entry *e = &adap->l2t->l2tab[idx];

        spin_lock(&e->lock);
        if (e->state != L2T_STATE_SWITCHING) {
            send_pending(adap, e);
            e->state = (e->neigh->nud_state & NUD_STALE) ?
                    L2T_STATE_STALE : L2T_STATE_VALID;
        }
        spin_unlock(&e->lock);
    }
}

/*
 * Add a packet to an L2T entry's queue of packets awaiting resolution.
 * Must be called with the entry's lock held.
 */
static inline void arpq_enqueue(struct l2t_entry *e, struct sk_buff *skb)
{
    skb->next = NULL;
    if (e->arpq_head)
        e->arpq_tail->next = skb;
    else
        e->arpq_head = skb;
    e->arpq_tail = skb;
}

int cxgb4_l2t_send(struct net_device *dev, struct sk_buff *skb,
           struct l2t_entry *e)
{
    struct adapter *adap = netdev2adap(dev);

again:
    switch (e->state) {
    case L2T_STATE_STALE:     /* entry is stale, kick off revalidation */
        neigh_event_send(e->neigh, NULL);
        spin_lock_bh(&e->lock);
        if (e->state == L2T_STATE_STALE)
            e->state = L2T_STATE_VALID;
        spin_unlock_bh(&e->lock);
    case L2T_STATE_VALID:     /* fast-path, send the packet on */
        return t4_ofld_send(adap, skb);
    case L2T_STATE_RESOLVING:
    case L2T_STATE_SYNC_WRITE:
        spin_lock_bh(&e->lock);
        if (e->state != L2T_STATE_SYNC_WRITE &&
            e->state != L2T_STATE_RESOLVING) {
            spin_unlock_bh(&e->lock);
            goto again;
        }
        arpq_enqueue(e, skb);
        spin_unlock_bh(&e->lock);

        if (e->state == L2T_STATE_RESOLVING &&
            !neigh_event_send(e->neigh, NULL)) {
            spin_lock_bh(&e->lock);
            if (e->state == L2T_STATE_RESOLVING && e->arpq_head)
                write_l2e(adap, e, 1);
            spin_unlock_bh(&e->lock);
        }
    }
    return 0;
}
EXPORT_SYMBOL(cxgb4_l2t_send);

/*
 * Allocate a free L2T entry.  Must be called with l2t_data.lock held.
 */
static struct l2t_entry *alloc_l2e(struct l2t_data *d)
{
    struct l2t_entry *end, *e, **p;

    if (!atomic_read(&d->nfree))
        return NULL;

    /* there's definitely a free entry */
    for (e = d->rover, end = &d->l2tab[L2T_SIZE]; e != end; ++e)
        if (atomic_read(&e->refcnt) == 0)
            goto found;

    for (e = d->l2tab; atomic_read(&e->refcnt); ++e)
        ;
found:
    d->rover = e + 1;
    atomic_dec(&d->nfree);

    /*
     * The entry we found may be an inactive entry that is
     * presently in the hash table.  We need to remove it.
     */
    if (e->state < L2T_STATE_SWITCHING)
        for (p = &d->l2tab[e->hash].first; *p; p = &(*p)->next)
            if (*p == e) {
                *p = e->next;
                e->next = NULL;
                break;
            }

    e->state = L2T_STATE_UNUSED;
    return e;
}

/*
 * Called when an L2T entry has no more users.
 */
static void t4_l2e_free(struct l2t_entry *e)
{
    struct l2t_data *d;

    spin_lock_bh(&e->lock);
    if (atomic_read(&e->refcnt) == 0) {  /* hasn't been recycled */
        if (e->neigh) {
            neigh_release(e->neigh);
            e->neigh = NULL;
        }
        while (e->arpq_head) {
            struct sk_buff *skb = e->arpq_head;

            e->arpq_head = skb->next;
            kfree_skb(skb);
        }
        e->arpq_tail = NULL;
    }
    spin_unlock_bh(&e->lock);

    d = container_of(e, struct l2t_data, l2tab[e->idx]);
    atomic_inc(&d->nfree);
}

void cxgb4_l2t_release(struct l2t_entry *e)
{
    if (atomic_dec_and_test(&e->refcnt))
        t4_l2e_free(e);
}
EXPORT_SYMBOL(cxgb4_l2t_release);

/*
 * Update an L2T entry that was previously used for the same next hop as neigh.
 * Must be called with softirqs disabled.
 */
static void reuse_entry(struct l2t_entry *e, struct neighbour *neigh)
{
    unsigned int nud_state;

    spin_lock(&e->lock);                /* avoid race with t4_l2t_free */
    if (neigh != e->neigh)
        neigh_replace(e, neigh);
    nud_state = neigh->nud_state;
    if (memcmp(e->dmac, neigh->ha, sizeof(e->dmac)) ||
        !(nud_state & NUD_VALID))
        e->state = L2T_STATE_RESOLVING;
    else if (nud_state & NUD_CONNECTED)
        e->state = L2T_STATE_VALID;
    else
        e->state = L2T_STATE_STALE;
    spin_unlock(&e->lock);
}

struct l2t_entry *cxgb4_l2t_get(struct l2t_data *d, struct neighbour *neigh,
                const struct net_device *physdev,
                unsigned int priority)
{
    u8 lport;
    u16 vlan;
    struct l2t_entry *e;
    int addr_len = neigh->tbl->key_len;
    u32 *addr = (u32 *)neigh->primary_key;
    int ifidx = neigh->dev->ifindex;
    int hash = addr_hash(addr, addr_len, ifidx);

    if (neigh->dev->flags & IFF_LOOPBACK)
        lport = netdev2pinfo(physdev)->tx_chan + 4;
    else
        lport = netdev2pinfo(physdev)->lport;

    if (neigh->dev->priv_flags & IFF_802_1Q_VLAN)
        vlan = vlan_dev_vlan_id(neigh->dev);
    else
        vlan = VLAN_NONE;

    write_lock_bh(&d->lock);
    for (e = d->l2tab[hash].first; e; e = e->next)
        if (!addreq(e, addr) && e->ifindex == ifidx &&
            e->vlan == vlan && e->lport == lport) {
            l2t_hold(d, e);
            if (atomic_read(&e->refcnt) == 1)
                reuse_entry(e, neigh);
            goto done;
        }

    /* Need to allocate a new entry */
    e = alloc_l2e(d);
    if (e) {
        spin_lock(&e->lock);          /* avoid race with t4_l2t_free */
        e->state = L2T_STATE_RESOLVING;
        memcpy(e->addr, addr, addr_len);
        e->ifindex = ifidx;
        e->hash = hash;
        e->lport = lport;
        e->v6 = addr_len == 16;
        atomic_set(&e->refcnt, 1);
        neigh_replace(e, neigh);
        e->vlan = vlan;
        e->next = d->l2tab[hash].first;
        d->l2tab[hash].first = e;
        spin_unlock(&e->lock);
    }
done:
    write_unlock_bh(&d->lock);
    return e;
}
EXPORT_SYMBOL(cxgb4_l2t_get);

/*
 * Called when address resolution fails for an L2T entry to handle packets
 * on the arpq head.  If a packet specifies a failure handler it is invoked,
 * otherwise the packet is sent to the device.
 */
static void handle_failed_resolution(struct adapter *adap, struct sk_buff *arpq)
{
    while (arpq) {
        struct sk_buff *skb = arpq;
        const struct l2t_skb_cb *cb = L2T_SKB_CB(skb);

        arpq = skb->next;
        skb->next = NULL;
        if (cb->arp_err_handler)
            cb->arp_err_handler(cb->handle, skb);
        else
            t4_ofld_send(adap, skb);
    }
}

/*
 * Called when the host's neighbor layer makes a change to some entry that is
 * loaded into the HW L2 table.
 */
void t4_l2t_update(struct adapter *adap, struct neighbour *neigh)
{
    struct l2t_entry *e;
    struct sk_buff *arpq = NULL;
    struct l2t_data *d = adap->l2t;
    int addr_len = neigh->tbl->key_len;
    u32 *addr = (u32 *) neigh->primary_key;
    int ifidx = neigh->dev->ifindex;
    int hash = addr_hash(addr, addr_len, ifidx);

    read_lock_bh(&d->lock);
    for (e = d->l2tab[hash].first; e; e = e->next)
        if (!addreq(e, addr) && e->ifindex == ifidx) {
            spin_lock(&e->lock);
            if (atomic_read(&e->refcnt))
                goto found;
            spin_unlock(&e->lock);
            break;
        }
    read_unlock_bh(&d->lock);
    return;

 found:
    read_unlock(&d->lock);

    if (neigh != e->neigh)
        neigh_replace(e, neigh);

    if (e->state == L2T_STATE_RESOLVING) {
        if (neigh->nud_state & NUD_FAILED) {
            arpq = e->arpq_head;
            e->arpq_head = e->arpq_tail = NULL;
        } else if ((neigh->nud_state & (NUD_CONNECTED | NUD_STALE)) &&
               e->arpq_head) {
            write_l2e(adap, e, 1);
        }
    } else {
        e->state = neigh->nud_state & NUD_CONNECTED ?
            L2T_STATE_VALID : L2T_STATE_STALE;
        if (memcmp(e->dmac, neigh->ha, sizeof(e->dmac)))
            write_l2e(adap, e, 0);
    }

    spin_unlock_bh(&e->lock);

    if (arpq)
        handle_failed_resolution(adap, arpq);
}

struct l2t_data *t4_init_l2t(void)
{
    int i;
    struct l2t_data *d;

    d = t4_alloc_mem(sizeof(*d));
    if (!d)
        return NULL;

    d->rover = d->l2tab;
    atomic_set(&d->nfree, L2T_SIZE);
    rwlock_init(&d->lock);

    for (i = 0; i < L2T_SIZE; ++i) {
        d->l2tab[i].idx = i;
        d->l2tab[i].state = L2T_STATE_UNUSED;
        spin_lock_init(&d->l2tab[i].lock);
        atomic_set(&d->l2tab[i].refcnt, 0);
    }
    return d;
}

static inline void *l2t_get_idx(struct seq_file *seq, loff_t pos)
{
    struct l2t_entry *l2tab = seq->private;

    return pos >= L2T_SIZE ? NULL : &l2tab[pos];
}

static void *l2t_seq_start(struct seq_file *seq, loff_t *pos)
{
    return *pos ? l2t_get_idx(seq, *pos - 1) : SEQ_START_TOKEN;
}

static void *l2t_seq_next(struct seq_file *seq, void *v, loff_t *pos)
{
    v = l2t_get_idx(seq, *pos);
    if (v)
        ++*pos;
    return v;
}

static void l2t_seq_stop(struct seq_file *seq, void *v)
{
}

static char l2e_state(const struct l2t_entry *e)
{
    switch (e->state) {
    case L2T_STATE_VALID: return 'V';
    case L2T_STATE_STALE: return 'S';
    case L2T_STATE_SYNC_WRITE: return 'W';
    case L2T_STATE_RESOLVING: return e->arpq_head ? 'A' : 'R';
    case L2T_STATE_SWITCHING: return 'X';
    default:
        return 'U';
    }
}

static int l2t_seq_show(struct seq_file *seq, void *v)
{
    if (v == SEQ_START_TOKEN)
        seq_puts(seq, " Idx IP address                "
             "Ethernet address  VLAN/P LP State Users Port\n");
    else {
        char ip[60];
        struct l2t_entry *e = v;

        spin_lock_bh(&e->lock);
        if (e->state == L2T_STATE_SWITCHING)
            ip[0] = '\0';
        else
            sprintf(ip, e->v6 ? "%pI6c" : "%pI4", e->addr);
        seq_printf(seq, "%4u %-25s %17pM %4d %u %2u   %c   %5u %s\n",
               e->idx, ip, e->dmac,
               e->vlan & VLAN_VID_MASK, vlan_prio(e), e->lport,
               l2e_state(e), atomic_read(&e->refcnt),
               e->neigh ? e->neigh->dev->name : "");
        spin_unlock_bh(&e->lock);
    }
    return 0;
}

static const struct seq_operations l2t_seq_ops = {
    .start = l2t_seq_start,
    .next = l2t_seq_next,
    .stop = l2t_seq_stop,
    .show = l2t_seq_show
};

static int l2t_seq_open(struct inode *inode, struct file *file)
{
    int rc = seq_open(file, &l2t_seq_ops);

    if (!rc) {
        struct adapter *adap = inode->i_private;
        struct seq_file *seq = file->private_data;

        seq->private = adap->l2t->l2tab;
    }
    return rc;
}

const struct file_operations t4_l2t_fops = {
    .owner = THIS_MODULE,
    .open = l2t_seq_open,
    .read = seq_read,
    .llseek = seq_lseek,
    .release = seq_release,
};