- 根目录:
- drivers
- net
- ethernet
- chelsio
- cxgb3
- l2t.c
/*
* Copyright (c) 2003-2008 Chelsio, 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/slab.h>
#include <linux/export.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;
struct sk_buff *tmp;
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);
skb_queue_walk_safe(&e->arpq, skb, tmp) {
__skb_unlink(skb, &e->arpq);
cxgb3_ofld_send(dev, skb);
}
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_queue_tail(&e->arpq, 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 (!skb_queue_empty(&e->arpq))
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);
}
}
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 dst_entry *dst,
struct net_device *dev, const void *daddr)
{
struct l2t_entry *e = NULL;
struct neighbour *neigh;
struct port_info *p;
struct l2t_data *d;
int hash;
u32 addr;
int ifidx;
int smt_idx;
rcu_read_lock();
neigh = dst_neigh_lookup(dst, daddr);
if (!neigh)
goto done_rcu;
addr = *(u32 *) neigh->primary_key;
ifidx = neigh->dev->ifindex;
if (!dev)
dev = neigh->dev;
p = netdev_priv(dev);
smt_idx = p->port_id;
d = L2DATA(cdev);
if (!d)
goto done_rcu;
hash = arp_hash(addr, ifidx, d);
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_unlock;
}
/* 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_vlan_id(neigh->dev);
else
e->vlan = VLAN_NONE;
spin_unlock(&e->lock);
}
done_unlock:
write_unlock_bh(&d->lock);
done_rcu:
if (neigh)
neigh_release(neigh);
rcu_read_unlock();
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_head *arpq)
{
struct sk_buff *skb, *tmp;
skb_queue_walk_safe(arpq, skb, tmp) {
struct l2t_skb_cb *cb = L2T_SKB_CB(skb);
__skb_unlink(skb, arpq);
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 sk_buff_head arpq;
struct l2t_entry *e;
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:
__skb_queue_head_init(&arpq);
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) {
skb_queue_splice_init(&e->arpq, &arpq);
} else if (neigh->nud_state & (NUD_CONNECTED|NUD_STALE))
setup_l2e_send_pending(dev, NULL, e);
} else {
e->state = neigh->nud_state & NUD_CONNECTED ?
L2T_STATE_VALID : L2T_STATE_STALE;
if (!ether_addr_equal(e->dmac, neigh->ha))
setup_l2e_send_pending(dev, NULL, e);
}
}
spin_unlock_bh(&e->lock);
if (!skb_queue_empty(&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;
__skb_queue_head_init(&d->l2tab[i].arpq);
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);
}