diff options
Diffstat (limited to 'drivers/net/cxgb3/l2t.c')
| -rw-r--r-- | drivers/net/cxgb3/l2t.c | 450 |
1 files changed, 450 insertions, 0 deletions
diff --git a/drivers/net/cxgb3/l2t.c b/drivers/net/cxgb3/l2t.c new file mode 100644 index 0000000..3c0cb85 --- /dev/null +++ b/drivers/net/cxgb3/l2t.c @@ -0,0 +1,450 @@ +/* + * Copyright (c) 2003-2007 Chelsio, Inc. All rights reserved. + * Copyright (c) 2006-2007 Open Grid Computing, 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 <net/neighbour.h> +#include "common.h" +#include "t3cdev.h" +#include "cxgb3_defs.h" +#include "l2t.h" +#include "t3_cpl.h" +#include "firmware_exports.h" + +#define VLAN_NONE 0xfff + +/* + * Module locking notes: There is a RW lock protecting the L2 table as a + * whole plus a spinlock per L2T entry. Entry lookups and allocations happen + * under the protection of the table lock, individual entry changes happen + * while holding that entry's spinlock. The table lock nests outside the + * entry locks. Allocations of new entries take the table lock as writers so + * no other lookups can happen while allocating new entries. Entry updates + * take the table lock as readers so multiple entries can be updated in + * parallel. An L2T entry can be dropped by decrementing its reference count + * and therefore can happen in parallel with entry allocation but no entry + * can change state or increment its ref count during allocation as both of + * these perform lookups. + */ + +static inline unsigned int vlan_prio(const struct l2t_entry *e) +{ + return e->vlan >> 13; +} + +static inline unsigned int arp_hash(u32 key, int ifindex, + const struct l2t_data *d) +{ + return jhash_2words(key, ifindex, 0) & (d->nentries - 1); +} + +static inline void neigh_replace(struct l2t_entry *e, struct neighbour *n) +{ + neigh_hold(n); + if (e->neigh) + neigh_release(e->neigh); + e->neigh = n; +} + +/* + * Set up an L2T entry and send any packets waiting in the arp queue. The + * supplied skb is used for the CPL_L2T_WRITE_REQ. Must be called with the + * entry locked. + */ +static int setup_l2e_send_pending(struct t3cdev *dev, struct sk_buff *skb, + struct l2t_entry *e) +{ + struct cpl_l2t_write_req *req; + + if (!skb) { + skb = alloc_skb(sizeof(*req), GFP_ATOMIC); + if (!skb) + return -ENOMEM; + } + + req = (struct cpl_l2t_write_req *)__skb_put(skb, sizeof(*req)); + req->wr.wr_hi = htonl(V_WR_OP(FW_WROPCODE_FORWARD)); + OPCODE_TID(req) = htonl(MK_OPCODE_TID(CPL_L2T_WRITE_REQ, e->idx)); + req->params = htonl(V_L2T_W_IDX(e->idx) | V_L2T_W_IFF(e->smt_idx) | + V_L2T_W_VLAN(e->vlan & VLAN_VID_MASK) | + V_L2T_W_PRIO(vlan_prio(e))); + memcpy(e->dmac, e->neigh->ha, sizeof(e->dmac)); + memcpy(req->dst_mac, e->dmac, sizeof(req->dst_mac)); + skb->priority = CPL_PRIORITY_CONTROL; + cxgb3_ofld_send(dev, skb); + while (e->arpq_head) { + skb = e->arpq_head; + e->arpq_head = skb->next; + skb->next = NULL; + cxgb3_ofld_send(dev, skb); + } + e->arpq_tail = NULL; + e->state = L2T_STATE_VALID; + + return 0; +} + +/* + * Add a packet to the 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 t3_l2t_send_slow(struct t3cdev *dev, struct sk_buff *skb, + struct l2t_entry *e) +{ +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 cxgb3_ofld_send(dev, skb); + case L2T_STATE_RESOLVING: + spin_lock_bh(&e->lock); + if (e->state != L2T_STATE_RESOLVING) { + /* ARP already completed */ + spin_unlock_bh(&e->lock); + goto again; + } + arpq_enqueue(e, skb); + spin_unlock_bh(&e->lock); + + /* + * Only the first packet added to the arpq should kick off + * resolution. However, because the alloc_skb below can fail, + * we allow each packet added to the arpq to retry resolution + * as a way of recovering from transient memory exhaustion. + * A better way would be to use a work request to retry L2T + * entries when there's no memory. + */ + if (!neigh_event_send(e->neigh, NULL)) { + skb = alloc_skb(sizeof(struct cpl_l2t_write_req), + GFP_ATOMIC); + if (!skb) + break; + + spin_lock_bh(&e->lock); + if (e->arpq_head) + setup_l2e_send_pending(dev, skb, e); + else /* we lost the race */ + __kfree_skb(skb); + spin_unlock_bh(&e->lock); + } + } + return 0; +} + +EXPORT_SYMBOL(t3_l2t_send_slow); + +void t3_l2t_send_event(struct t3cdev *dev, struct l2t_entry *e) +{ +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); + return; + case L2T_STATE_VALID: /* fast-path, send the packet on */ + return; + case L2T_STATE_RESOLVING: + spin_lock_bh(&e->lock); + if (e->state != L2T_STATE_RESOLVING) { + /* ARP already completed */ + spin_unlock_bh(&e->lock); + goto again; + } + spin_unlock_bh(&e->lock); + + /* + * Only the first packet added to the arpq should kick off + * resolution. However, because the alloc_skb below can fail, + * we allow each packet added to the arpq to retry resolution + * as a way of recovering from transient memory exhaustion. + * A better way would be to use a work request to retry L2T + * entries when there's no memory. + */ + neigh_event_send(e->neigh, NULL); + } + return; +} + +EXPORT_SYMBOL(t3_l2t_send_event); + +/* + * 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[d->nentries]; e != end; ++e) + if (atomic_read(&e->refcnt) == 0) + goto found; + + for (e = &d->l2tab[1]; 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_UNUSED) { + int hash = arp_hash(e->addr, e->ifindex, d); + + for (p = &d->l2tab[hash].first; *p; p = &(*p)->next) + if (*p == e) { + *p = e->next; + break; + } + e->state = L2T_STATE_UNUSED; + } + return e; +} + +/* + * Called when an L2T entry has no more users. The entry is left in the hash + * table since it is likely to be reused but we also bump nfree to indicate + * that the entry can be reallocated for a different neighbor. We also drop + * the existing neighbor reference in case the neighbor is going away and is + * waiting on our reference. + * + * Because entries can be reallocated to other neighbors once their ref count + * drops to 0 we need to take the entry's lock to avoid races with a new + * incarnation. + */ +void t3_l2e_free(struct l2t_data *d, struct l2t_entry *e) +{ + 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; + } + } + spin_unlock_bh(&e->lock); + atomic_inc(&d->nfree); +} + +EXPORT_SYMBOL(t3_l2e_free); + +/* + * Update an L2T entry that was previously used for the same next hop as neigh. + * Must be called with softirqs disabled. + */ +static inline void reuse_entry(struct l2t_entry *e, struct neighbour *neigh) +{ + unsigned int nud_state; + + spin_lock(&e->lock); /* avoid race with t3_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 *t3_l2t_get(struct t3cdev *cdev, struct neighbour *neigh, + struct net_device *dev) +{ + struct l2t_entry *e; + struct l2t_data *d = L2DATA(cdev); + u32 addr = *(u32 *) neigh->primary_key; + int ifidx = neigh->dev->ifindex; + int hash = arp_hash(addr, ifidx, d); + struct port_info *p = netdev_priv(dev); + int smt_idx = p->port_id; + + write_lock_bh(&d->lock); + for (e = d->l2tab[hash].first; e; e = e->next) + if (e->addr == addr && e->ifindex == ifidx && + e->smt_idx == smt_idx) { + 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 t3_l2t_free */ + e->next = d->l2tab[hash].first; + d->l2tab[hash].first = e; + e->state = L2T_STATE_RESOLVING; + e->addr = addr; + e->ifindex = ifidx; + e->smt_idx = smt_idx; + atomic_set(&e->refcnt, 1); + neigh_replace(e, neigh); + if (neigh->dev->priv_flags & IFF_802_1Q_VLAN) + e->vlan = VLAN_DEV_INFO(neigh->dev)->vlan_id; + else + e->vlan = VLAN_NONE; + spin_unlock(&e->lock); + } +done: + write_unlock_bh(&d->lock); + return e; +} + +EXPORT_SYMBOL(t3_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 packets is sent to the offload device. + * + * XXX: maybe we should abandon the latter behavior and just require a failure + * handler. + */ +static void handle_failed_resolution(struct t3cdev *dev, struct sk_buff *arpq) +{ + while (arpq) { + struct sk_buff *skb = arpq; + struct l2t_skb_cb *cb = L2T_SKB_CB(skb); + + arpq = skb->next; + skb->next = NULL; + if (cb->arp_failure_handler) + cb->arp_failure_handler(dev, skb); + else + cxgb3_ofld_send(dev, skb); + } +} + +/* + * Called when the host's ARP layer makes a change to some entry that is + * loaded into the HW L2 table. + */ +void t3_l2t_update(struct t3cdev *dev, struct neighbour *neigh) +{ + struct l2t_entry *e; + struct sk_buff *arpq = NULL; + struct l2t_data *d = L2DATA(dev); + u32 addr = *(u32 *) neigh->primary_key; + int ifidx = neigh->dev->ifindex; + int hash = arp_hash(addr, ifidx, d); + + read_lock_bh(&d->lock); + for (e = d->l2tab[hash].first; e; e = e->next) + if (e->addr == addr && e->ifindex == ifidx) { + spin_lock(&e->lock); + goto found; + } + read_unlock_bh(&d->lock); + return; + +found: + read_unlock(&d->lock); + if (atomic_read(&e->refcnt)) { + 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_is_connected(neigh)) + setup_l2e_send_pending(dev, NULL, e); + } else { + e->state = neigh_is_connected(neigh) ? + L2T_STATE_VALID : L2T_STATE_STALE; + if (memcmp(e->dmac, neigh->ha, 6)) + setup_l2e_send_pending(dev, NULL, e); + } + } + spin_unlock_bh(&e->lock); + + if (arpq) + handle_failed_resolution(dev, arpq); +} + +struct l2t_data *t3_init_l2t(unsigned int l2t_capacity) +{ + struct l2t_data *d; + int i, size = sizeof(*d) + l2t_capacity * sizeof(struct l2t_entry); + + d = cxgb_alloc_mem(size); + if (!d) + return NULL; + + d->nentries = l2t_capacity; + d->rover = &d->l2tab[1]; /* entry 0 is not used */ + atomic_set(&d->nfree, l2t_capacity - 1); + rwlock_init(&d->lock); + + for (i = 0; i < l2t_capacity; ++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; +} + +void t3_free_l2t(struct l2t_data *d) +{ + cxgb_free_mem(d); +} + |