0369f98e9f3ac16340b3a0d2834e860e1ef6de0f
[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
22 #include <net/sock.h>
23
24 struct request_sock;
25 struct sk_buff;
26 struct dst_entry;
27 struct proto;
28
29 struct request_sock_ops {
30         int             family;
31         int             obj_size;
32         struct kmem_cache       *slab;
33         int             (*rtx_syn_ack)(struct sock *sk,
34                                        struct request_sock *req);
35         void            (*send_ack)(struct sk_buff *skb,
36                                     struct request_sock *req);
37         void            (*send_reset)(struct sock *sk,
38                                       struct sk_buff *skb);
39         void            (*destructor)(struct request_sock *req);
40 };
41
42 /* struct request_sock - mini sock to represent a connection request
43  */
44 struct request_sock {
45         struct request_sock             *dl_next; /* Must be first member! */
46         u16                             mss;
47         u8                              retrans;
48         u8                              __pad;
49         /* The following two fields can be easily recomputed I think -AK */
50         u32                             window_clamp; /* window clamp at creation time */
51         u32                             rcv_wnd;          /* rcv_wnd offered first time */
52         u32                             ts_recent;
53         unsigned long                   expires;
54         const struct request_sock_ops   *rsk_ops;
55         struct sock                     *sk;
56         u32                             secid;
57         u32                             peer_secid;
58 };
59
60 static inline struct request_sock *reqsk_alloc(const struct request_sock_ops *ops)
61 {
62         struct request_sock *req = kmem_cache_alloc(ops->slab, GFP_ATOMIC);
63
64         if (req != NULL)
65                 req->rsk_ops = ops;
66
67         return req;
68 }
69
70 static inline void __reqsk_free(struct request_sock *req)
71 {
72         kmem_cache_free(req->rsk_ops->slab, req);
73 }
74
75 static inline void reqsk_free(struct request_sock *req)
76 {
77         req->rsk_ops->destructor(req);
78         __reqsk_free(req);
79 }
80
81 extern int sysctl_max_syn_backlog;
82
83 /** struct listen_sock - listen state
84  *
85  * @max_qlen_log - log_2 of maximal queued SYNs/REQUESTs
86  */
87 struct listen_sock {
88         u8                      max_qlen_log;
89         /* 3 bytes hole, try to use */
90         int                     qlen;
91         int                     qlen_young;
92         int                     clock_hand;
93         u32                     hash_rnd;
94         u32                     nr_table_entries;
95         struct request_sock     *syn_table[0];
96 };
97
98 /** struct request_sock_queue - queue of request_socks
99  *
100  * @rskq_accept_head - FIFO head of established children
101  * @rskq_accept_tail - FIFO tail of established children
102  * @rskq_defer_accept - User waits for some data after accept()
103  * @syn_wait_lock - serializer
104  *
105  * %syn_wait_lock is necessary only to avoid proc interface having to grab the main
106  * lock sock while browsing the listening hash (otherwise it's deadlock prone).
107  *
108  * This lock is acquired in read mode only from listening_get_next() seq_file
109  * op and it's acquired in write mode _only_ from code that is actively
110  * changing rskq_accept_head. All readers that are holding the master sock lock
111  * don't need to grab this lock in read mode too as rskq_accept_head. writes
112  * are always protected from the main sock lock.
113  */
114 struct request_sock_queue {
115         struct request_sock     *rskq_accept_head;
116         struct request_sock     *rskq_accept_tail;
117         rwlock_t                syn_wait_lock;
118         u16                     rskq_defer_accept;
119         /* 2 bytes hole, try to pack */
120         struct listen_sock      *listen_opt;
121 };
122
123 extern int reqsk_queue_alloc(struct request_sock_queue *queue,
124                              unsigned int nr_table_entries);
125
126 extern void __reqsk_queue_destroy(struct request_sock_queue *queue);
127 extern void reqsk_queue_destroy(struct request_sock_queue *queue);
128
129 static inline struct request_sock *
130         reqsk_queue_yank_acceptq(struct request_sock_queue *queue)
131 {
132         struct request_sock *req = queue->rskq_accept_head;
133
134         queue->rskq_accept_head = NULL;
135         return req;
136 }
137
138 static inline int reqsk_queue_empty(struct request_sock_queue *queue)
139 {
140         return queue->rskq_accept_head == NULL;
141 }
142
143 static inline void reqsk_queue_unlink(struct request_sock_queue *queue,
144                                       struct request_sock *req,
145                                       struct request_sock **prev_req)
146 {
147         write_lock(&queue->syn_wait_lock);
148         *prev_req = req->dl_next;
149         write_unlock(&queue->syn_wait_lock);
150 }
151
152 static inline void reqsk_queue_add(struct request_sock_queue *queue,
153                                    struct request_sock *req,
154                                    struct sock *parent,
155                                    struct sock *child)
156 {
157         req->sk = child;
158         sk_acceptq_added(parent);
159
160         if (queue->rskq_accept_head == NULL)
161                 queue->rskq_accept_head = req;
162         else
163                 queue->rskq_accept_tail->dl_next = req;
164
165         queue->rskq_accept_tail = req;
166         req->dl_next = NULL;
167 }
168
169 static inline struct request_sock *reqsk_queue_remove(struct request_sock_queue *queue)
170 {
171         struct request_sock *req = queue->rskq_accept_head;
172
173         BUG_TRAP(req != NULL);
174
175         queue->rskq_accept_head = req->dl_next;
176         if (queue->rskq_accept_head == NULL)
177                 queue->rskq_accept_tail = NULL;
178
179         return req;
180 }
181
182 static inline struct sock *reqsk_queue_get_child(struct request_sock_queue *queue,
183                                                  struct sock *parent)
184 {
185         struct request_sock *req = reqsk_queue_remove(queue);
186         struct sock *child = req->sk;
187
188         BUG_TRAP(child != NULL);
189
190         sk_acceptq_removed(parent);
191         __reqsk_free(req);
192         return child;
193 }
194
195 static inline int reqsk_queue_removed(struct request_sock_queue *queue,
196                                       struct request_sock *req)
197 {
198         struct listen_sock *lopt = queue->listen_opt;
199
200         if (req->retrans == 0)
201                 --lopt->qlen_young;
202
203         return --lopt->qlen;
204 }
205
206 static inline int reqsk_queue_added(struct request_sock_queue *queue)
207 {
208         struct listen_sock *lopt = queue->listen_opt;
209         const int prev_qlen = lopt->qlen;
210
211         lopt->qlen_young++;
212         lopt->qlen++;
213         return prev_qlen;
214 }
215
216 static inline int reqsk_queue_len(const struct request_sock_queue *queue)
217 {
218         return queue->listen_opt != NULL ? queue->listen_opt->qlen : 0;
219 }
220
221 static inline int reqsk_queue_len_young(const struct request_sock_queue *queue)
222 {
223         return queue->listen_opt->qlen_young;
224 }
225
226 static inline int reqsk_queue_is_full(const struct request_sock_queue *queue)
227 {
228         return queue->listen_opt->qlen >> queue->listen_opt->max_qlen_log;
229 }
230
231 static inline void reqsk_queue_hash_req(struct request_sock_queue *queue,
232                                         u32 hash, struct request_sock *req,
233                                         unsigned long timeout)
234 {
235         struct listen_sock *lopt = queue->listen_opt;
236
237         req->expires = jiffies + timeout;
238         req->retrans = 0;
239         req->sk = NULL;
240         req->dl_next = lopt->syn_table[hash];
241
242         write_lock(&queue->syn_wait_lock);
243         lopt->syn_table[hash] = req;
244         write_unlock(&queue->syn_wait_lock);
245 }
246
247 #endif /* _REQUEST_SOCK_H */