net: convert BUG_TRAP to generic WARN_ON
[linux-3.10.git] / include / net / request_sock.h
1 /*
2  * NET          Generic infrastructure for Network protocols.
3  *
4  *              Definitions for request_sock 
5  *
6  * Authors:     Arnaldo Carvalho de Melo <acme@conectiva.com.br>
7  *
8  *              From code originally in include/net/tcp.h
9  *
10  *              This program is free software; you can redistribute it and/or
11  *              modify it under the terms of the GNU General Public License
12  *              as published by the Free Software Foundation; either version
13  *              2 of the License, or (at your option) any later version.
14  */
15 #ifndef _REQUEST_SOCK_H
16 #define _REQUEST_SOCK_H
17
18 #include <linux/slab.h>
19 #include <linux/spinlock.h>
20 #include <linux/types.h>
21 #include <linux/bug.h>
22
23 #include <net/sock.h>
24
25 struct request_sock;
26 struct sk_buff;
27 struct dst_entry;
28 struct proto;
29
30 struct request_sock_ops {
31         int             family;
32         int             obj_size;
33         struct kmem_cache       *slab;
34         int             (*rtx_syn_ack)(struct sock *sk,
35                                        struct request_sock *req);
36         void            (*send_ack)(struct sk_buff *skb,
37                                     struct request_sock *req);
38         void            (*send_reset)(struct sock *sk,
39                                       struct sk_buff *skb);
40         void            (*destructor)(struct request_sock *req);
41 };
42
43 /* struct request_sock - mini sock to represent a connection request
44  */
45 struct request_sock {
46         struct request_sock             *dl_next; /* Must be first member! */
47         u16                             mss;
48         u8                              retrans;
49         u8                              cookie_ts; /* syncookie: encode tcpopts in timestamp */
50         /* The following two fields can be easily recomputed I think -AK */
51         u32                             window_clamp; /* window clamp at creation time */
52         u32                             rcv_wnd;          /* rcv_wnd offered first time */
53         u32                             ts_recent;
54         unsigned long                   expires;
55         const struct request_sock_ops   *rsk_ops;
56         struct sock                     *sk;
57         u32                             secid;
58         u32                             peer_secid;
59 };
60
61 static inline struct request_sock *reqsk_alloc(const struct request_sock_ops *ops)
62 {
63         struct request_sock *req = kmem_cache_alloc(ops->slab, GFP_ATOMIC);
64
65         if (req != NULL)
66                 req->rsk_ops = ops;
67
68         return req;
69 }
70
71 static inline void __reqsk_free(struct request_sock *req)
72 {
73         kmem_cache_free(req->rsk_ops->slab, req);
74 }
75
76 static inline void reqsk_free(struct request_sock *req)
77 {
78         req->rsk_ops->destructor(req);
79         __reqsk_free(req);
80 }
81
82 extern int sysctl_max_syn_backlog;
83
84 /** struct listen_sock - listen state
85  *
86  * @max_qlen_log - log_2 of maximal queued SYNs/REQUESTs
87  */
88 struct listen_sock {
89         u8                      max_qlen_log;
90         /* 3 bytes hole, try to use */
91         int                     qlen;
92         int                     qlen_young;
93         int                     clock_hand;
94         u32                     hash_rnd;
95         u32                     nr_table_entries;
96         struct request_sock     *syn_table[0];
97 };
98
99 /** struct request_sock_queue - queue of request_socks
100  *
101  * @rskq_accept_head - FIFO head of established children
102  * @rskq_accept_tail - FIFO tail of established children
103  * @rskq_defer_accept - User waits for some data after accept()
104  * @syn_wait_lock - serializer
105  *
106  * %syn_wait_lock is necessary only to avoid proc interface having to grab the main
107  * lock sock while browsing the listening hash (otherwise it's deadlock prone).
108  *
109  * This lock is acquired in read mode only from listening_get_next() seq_file
110  * op and it's acquired in write mode _only_ from code that is actively
111  * changing rskq_accept_head. All readers that are holding the master sock lock
112  * don't need to grab this lock in read mode too as rskq_accept_head. writes
113  * are always protected from the main sock lock.
114  */
115 struct request_sock_queue {
116         struct request_sock     *rskq_accept_head;
117         struct request_sock     *rskq_accept_tail;
118         rwlock_t                syn_wait_lock;
119         u8                      rskq_defer_accept;
120         /* 3 bytes hole, try to pack */
121         struct listen_sock      *listen_opt;
122 };
123
124 extern int reqsk_queue_alloc(struct request_sock_queue *queue,
125                              unsigned int nr_table_entries);
126
127 extern void __reqsk_queue_destroy(struct request_sock_queue *queue);
128 extern void reqsk_queue_destroy(struct request_sock_queue *queue);
129
130 static inline struct request_sock *
131         reqsk_queue_yank_acceptq(struct request_sock_queue *queue)
132 {
133         struct request_sock *req = queue->rskq_accept_head;
134
135         queue->rskq_accept_head = NULL;
136         return req;
137 }
138
139 static inline int reqsk_queue_empty(struct request_sock_queue *queue)
140 {
141         return queue->rskq_accept_head == NULL;
142 }
143
144 static inline void reqsk_queue_unlink(struct request_sock_queue *queue,
145                                       struct request_sock *req,
146                                       struct request_sock **prev_req)
147 {
148         write_lock(&queue->syn_wait_lock);
149         *prev_req = req->dl_next;
150         write_unlock(&queue->syn_wait_lock);
151 }
152
153 static inline void reqsk_queue_add(struct request_sock_queue *queue,
154                                    struct request_sock *req,
155                                    struct sock *parent,
156                                    struct sock *child)
157 {
158         req->sk = child;
159         sk_acceptq_added(parent);
160
161         if (queue->rskq_accept_head == NULL)
162                 queue->rskq_accept_head = req;
163         else
164                 queue->rskq_accept_tail->dl_next = req;
165
166         queue->rskq_accept_tail = req;
167         req->dl_next = NULL;
168 }
169
170 static inline struct request_sock *reqsk_queue_remove(struct request_sock_queue *queue)
171 {
172         struct request_sock *req = queue->rskq_accept_head;
173
174         WARN_ON(req == NULL);
175
176         queue->rskq_accept_head = req->dl_next;
177         if (queue->rskq_accept_head == NULL)
178                 queue->rskq_accept_tail = NULL;
179
180         return req;
181 }
182
183 static inline struct sock *reqsk_queue_get_child(struct request_sock_queue *queue,
184                                                  struct sock *parent)
185 {
186         struct request_sock *req = reqsk_queue_remove(queue);
187         struct sock *child = req->sk;
188
189         WARN_ON(child == NULL);
190
191         sk_acceptq_removed(parent);
192         __reqsk_free(req);
193         return child;
194 }
195
196 static inline int reqsk_queue_removed(struct request_sock_queue *queue,
197                                       struct request_sock *req)
198 {
199         struct listen_sock *lopt = queue->listen_opt;
200
201         if (req->retrans == 0)
202                 --lopt->qlen_young;
203
204         return --lopt->qlen;
205 }
206
207 static inline int reqsk_queue_added(struct request_sock_queue *queue)
208 {
209         struct listen_sock *lopt = queue->listen_opt;
210         const int prev_qlen = lopt->qlen;
211
212         lopt->qlen_young++;
213         lopt->qlen++;
214         return prev_qlen;
215 }
216
217 static inline int reqsk_queue_len(const struct request_sock_queue *queue)
218 {
219         return queue->listen_opt != NULL ? queue->listen_opt->qlen : 0;
220 }
221
222 static inline int reqsk_queue_len_young(const struct request_sock_queue *queue)
223 {
224         return queue->listen_opt->qlen_young;
225 }
226
227 static inline int reqsk_queue_is_full(const struct request_sock_queue *queue)
228 {
229         return queue->listen_opt->qlen >> queue->listen_opt->max_qlen_log;
230 }
231
232 static inline void reqsk_queue_hash_req(struct request_sock_queue *queue,
233                                         u32 hash, struct request_sock *req,
234                                         unsigned long timeout)
235 {
236         struct listen_sock *lopt = queue->listen_opt;
237
238         req->expires = jiffies + timeout;
239         req->retrans = 0;
240         req->sk = NULL;
241         req->dl_next = lopt->syn_table[hash];
242
243         write_lock(&queue->syn_wait_lock);
244         lopt->syn_table[hash] = req;
245         write_unlock(&queue->syn_wait_lock);
246 }
247
248 #endif /* _REQUEST_SOCK_H */