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/*
* 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 <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);
}
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);
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