1 /*
2  * Copyright (c) 2003-2008 Chelsio, Inc. All rights reserved.
3  *
4  * This software is available to you under a choice of one of two
5  * licenses.  You may choose to be licensed under the terms of the GNU
6  * General Public License (GPL) Version 2, available from the file
7  * COPYING in the main directory of this source tree, or the
8  * OpenIB.org BSD license below:
9  *
10  *     Redistribution and use in source and binary forms, with or
11  *     without modification, are permitted provided that the following
12  *     conditions are met:
13  *
14  *      - Redistributions of source code must retain the above
15  *        copyright notice, this list of conditions and the following
16  *        disclaimer.
17  *
18  *      - Redistributions in binary form must reproduce the above
19  *        copyright notice, this list of conditions and the following
20  *        disclaimer in the documentation and/or other materials
21  *        provided with the distribution.
22  *
23  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
24  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
25  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
26  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
27  * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
28  * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
29  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
30  * SOFTWARE.
31  */
32 #ifndef _CHELSIO_L2T_H
33 #define _CHELSIO_L2T_H
34 
35 #include <linux/spinlock.h>
36 #include "t3cdev.h"
37 #include <linux/atomic.h>
38 
39 enum {
40 	L2T_STATE_VALID,	/* entry is up to date */
41 	L2T_STATE_STALE,	/* entry may be used but needs revalidation */
42 	L2T_STATE_RESOLVING,	/* entry needs address resolution */
43 	L2T_STATE_UNUSED	/* entry not in use */
44 };
45 
46 struct neighbour;
47 struct sk_buff;
48 
49 /*
50  * Each L2T entry plays multiple roles.  First of all, it keeps state for the
51  * corresponding entry of the HW L2 table and maintains a queue of offload
52  * packets awaiting address resolution.  Second, it is a node of a hash table
53  * chain, where the nodes of the chain are linked together through their next
54  * pointer.  Finally, each node is a bucket of a hash table, pointing to the
55  * first element in its chain through its first pointer.
56  */
57 struct l2t_entry {
58 	u16 state;		/* entry state */
59 	u16 idx;		/* entry index */
60 	u32 addr;		/* dest IP address */
61 	int ifindex;		/* neighbor's net_device's ifindex */
62 	u16 smt_idx;		/* SMT index */
63 	u16 vlan;		/* VLAN TCI (id: bits 0-11, prio: 13-15 */
64 	struct neighbour *neigh;	/* associated neighbour */
65 	struct l2t_entry *first;	/* start of hash chain */
66 	struct l2t_entry *next;	/* next l2t_entry on chain */
67 	struct sk_buff_head arpq;	/* queue of packets awaiting resolution */
68 	spinlock_t lock;
69 	atomic_t refcnt;	/* entry reference count */
70 	u8 dmac[6];		/* neighbour's MAC address */
71 };
72 
73 struct l2t_data {
74 	unsigned int nentries;	/* number of entries */
75 	struct l2t_entry *rover;	/* starting point for next allocation */
76 	atomic_t nfree;		/* number of free entries */
77 	rwlock_t lock;
78 	struct l2t_entry l2tab[0];
79 	struct rcu_head rcu_head;	/* to handle rcu cleanup */
80 };
81 
82 typedef void (*arp_failure_handler_func)(struct t3cdev * dev,
83 					 struct sk_buff * skb);
84 
85 /*
86  * Callback stored in an skb to handle address resolution failure.
87  */
88 struct l2t_skb_cb {
89 	arp_failure_handler_func arp_failure_handler;
90 };
91 
92 #define L2T_SKB_CB(skb) ((struct l2t_skb_cb *)(skb)->cb)
93 
94 static inline void set_arp_failure_handler(struct sk_buff *skb,
95 					   arp_failure_handler_func hnd)
96 {
97 	L2T_SKB_CB(skb)->arp_failure_handler = hnd;
98 }
99 
100 /*
101  * Getting to the L2 data from an offload device.
102  */
103 #define L2DATA(cdev) (rcu_dereference((cdev)->l2opt))
104 
105 #define W_TCB_L2T_IX    0
106 #define S_TCB_L2T_IX    7
107 #define M_TCB_L2T_IX    0x7ffULL
108 #define V_TCB_L2T_IX(x) ((x) << S_TCB_L2T_IX)
109 
110 void t3_l2e_free(struct l2t_data *d, struct l2t_entry *e);
111 void t3_l2t_update(struct t3cdev *dev, struct neighbour *neigh);
112 struct l2t_entry *t3_l2t_get(struct t3cdev *cdev, struct dst_entry *dst,
113 			     struct net_device *dev, const void *daddr);
114 int t3_l2t_send_slow(struct t3cdev *dev, struct sk_buff *skb,
115 		     struct l2t_entry *e);
116 void t3_l2t_send_event(struct t3cdev *dev, struct l2t_entry *e);
117 struct l2t_data *t3_init_l2t(unsigned int l2t_capacity);
118 void t3_free_l2t(struct l2t_data *d);
119 
120 int cxgb3_ofld_send(struct t3cdev *dev, struct sk_buff *skb);
121 
122 static inline int l2t_send(struct t3cdev *dev, struct sk_buff *skb,
123 			   struct l2t_entry *e)
124 {
125 	if (likely(e->state == L2T_STATE_VALID))
126 		return cxgb3_ofld_send(dev, skb);
127 	return t3_l2t_send_slow(dev, skb, e);
128 }
129 
130 static inline void l2t_release(struct t3cdev *t, struct l2t_entry *e)
131 {
132 	struct l2t_data *d;
133 
134 	rcu_read_lock();
135 	d = L2DATA(t);
136 
137 	if (atomic_dec_and_test(&e->refcnt) && d)
138 		t3_l2e_free(d, e);
139 
140 	rcu_read_unlock();
141 }
142 
143 static inline void l2t_hold(struct l2t_data *d, struct l2t_entry *e)
144 {
145 	if (d && atomic_add_return(1, &e->refcnt) == 1)	/* 0 -> 1 transition */
146 		atomic_dec(&d->nfree);
147 }
148 
149 #endif
150