tcp: account SYN-ACK timeouts & retransmissions
[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 /* empty to "strongly type" an otherwise void parameter.
31  */
32 struct request_values {
33 };
34
35 struct request_sock_ops {
36         int             family;
37         int             obj_size;
38         struct kmem_cache       *slab;
39         char            *slab_name;
40         int             (*rtx_syn_ack)(struct sock *sk,
41                                        struct request_sock *req,
42                                        struct request_values *rvp);
43         void            (*send_ack)(struct sock *sk, struct sk_buff *skb,
44                                     struct request_sock *req);
45         void            (*send_reset)(struct sock *sk,
46                                       struct sk_buff *skb);
47         void            (*destructor)(struct request_sock *req);
48         void            (*syn_ack_timeout)(struct sock *sk,
49                                            struct request_sock *req);
50 };
51
52 /* struct request_sock - mini sock to represent a connection request
53  */
54 struct request_sock {
55         struct request_sock             *dl_next; /* Must be first member! */
56         u16                             mss;
57         u8                              retrans;
58         u8                              cookie_ts; /* syncookie: encode tcpopts in timestamp */
59         /* The following two fields can be easily recomputed I think -AK */
60         u32                             window_clamp; /* window clamp at creation time */
61         u32                             rcv_wnd;          /* rcv_wnd offered first time */
62         u32                             ts_recent;
63         unsigned long                   expires;
64         const struct request_sock_ops   *rsk_ops;
65         struct sock                     *sk;
66         u32                             secid;
67         u32                             peer_secid;
68 };
69
70 static inline struct request_sock *reqsk_alloc(const struct request_sock_ops *ops)
71 {
72         struct request_sock *req = kmem_cache_alloc(ops->slab, GFP_ATOMIC);
73
74         if (req != NULL)
75                 req->rsk_ops = ops;
76
77         return req;
78 }
79
80 static inline void __reqsk_free(struct request_sock *req)
81 {
82         kmem_cache_free(req->rsk_ops->slab, req);
83 }
84
85 static inline void reqsk_free(struct request_sock *req)
86 {
87         req->rsk_ops->destructor(req);
88         __reqsk_free(req);
89 }
90
91 extern int sysctl_max_syn_backlog;
92
93 /** struct listen_sock - listen state
94  *
95  * @max_qlen_log - log_2 of maximal queued SYNs/REQUESTs
96  */
97 struct listen_sock {
98         u8                      max_qlen_log;
99         /* 3 bytes hole, try to use */
100         int                     qlen;
101         int                     qlen_young;
102         int                     clock_hand;
103         u32                     hash_rnd;
104         u32                     nr_table_entries;
105         struct request_sock     *syn_table[0];
106 };
107
108 /** struct request_sock_queue - queue of request_socks
109  *
110  * @rskq_accept_head - FIFO head of established children
111  * @rskq_accept_tail - FIFO tail of established children
112  * @rskq_defer_accept - User waits for some data after accept()
113  * @syn_wait_lock - serializer
114  *
115  * %syn_wait_lock is necessary only to avoid proc interface having to grab the main
116  * lock sock while browsing the listening hash (otherwise it's deadlock prone).
117  *
118  * This lock is acquired in read mode only from listening_get_next() seq_file
119  * op and it's acquired in write mode _only_ from code that is actively
120  * changing rskq_accept_head. All readers that are holding the master sock lock
121  * don't need to grab this lock in read mode too as rskq_accept_head. writes
122  * are always protected from the main sock lock.
123  */
124 struct request_sock_queue {
125         struct request_sock     *rskq_accept_head;
126         struct request_sock     *rskq_accept_tail;
127         rwlock_t                syn_wait_lock;
128         u8                      rskq_defer_accept;
129         /* 3 bytes hole, try to pack */
130         struct listen_sock      *listen_opt;
131 };
132
133 extern int reqsk_queue_alloc(struct request_sock_queue *queue,
134                              unsigned int nr_table_entries);
135
136 extern void __reqsk_queue_destroy(struct request_sock_queue *queue);
137 extern void reqsk_queue_destroy(struct request_sock_queue *queue);
138
139 static inline struct request_sock *
140         reqsk_queue_yank_acceptq(struct request_sock_queue *queue)
141 {
142         struct request_sock *req = queue->rskq_accept_head;
143
144         queue->rskq_accept_head = NULL;
145         return req;
146 }
147
148 static inline int reqsk_queue_empty(struct request_sock_queue *queue)
149 {
150         return queue->rskq_accept_head == NULL;
151 }
152
153 static inline void reqsk_queue_unlink(struct request_sock_queue *queue,
154                                       struct request_sock *req,
155                                       struct request_sock **prev_req)
156 {
157         write_lock(&queue->syn_wait_lock);
158         *prev_req = req->dl_next;
159         write_unlock(&queue->syn_wait_lock);
160 }
161
162 static inline void reqsk_queue_add(struct request_sock_queue *queue,
163                                    struct request_sock *req,
164                                    struct sock *parent,
165                                    struct sock *child)
166 {
167         req->sk = child;
168         sk_acceptq_added(parent);
169
170         if (queue->rskq_accept_head == NULL)
171                 queue->rskq_accept_head = req;
172         else
173                 queue->rskq_accept_tail->dl_next = req;
174
175         queue->rskq_accept_tail = req;
176         req->dl_next = NULL;
177 }
178
179 static inline struct request_sock *reqsk_queue_remove(struct request_sock_queue *queue)
180 {
181         struct request_sock *req = queue->rskq_accept_head;
182
183         WARN_ON(req == NULL);
184
185         queue->rskq_accept_head = req->dl_next;
186         if (queue->rskq_accept_head == NULL)
187                 queue->rskq_accept_tail = NULL;
188
189         return req;
190 }
191
192 static inline struct sock *reqsk_queue_get_child(struct request_sock_queue *queue,
193                                                  struct sock *parent)
194 {
195         struct request_sock *req = reqsk_queue_remove(queue);
196         struct sock *child = req->sk;
197
198         WARN_ON(child == NULL);
199
200         sk_acceptq_removed(parent);
201         __reqsk_free(req);
202         return child;
203 }
204
205 static inline int reqsk_queue_removed(struct request_sock_queue *queue,
206                                       struct request_sock *req)
207 {
208         struct listen_sock *lopt = queue->listen_opt;
209
210         if (req->retrans == 0)
211                 --lopt->qlen_young;
212
213         return --lopt->qlen;
214 }
215
216 static inline int reqsk_queue_added(struct request_sock_queue *queue)
217 {
218         struct listen_sock *lopt = queue->listen_opt;
219         const int prev_qlen = lopt->qlen;
220
221         lopt->qlen_young++;
222         lopt->qlen++;
223         return prev_qlen;
224 }
225
226 static inline int reqsk_queue_len(const struct request_sock_queue *queue)
227 {
228         return queue->listen_opt != NULL ? queue->listen_opt->qlen : 0;
229 }
230
231 static inline int reqsk_queue_len_young(const struct request_sock_queue *queue)
232 {
233         return queue->listen_opt->qlen_young;
234 }
235
236 static inline int reqsk_queue_is_full(const struct request_sock_queue *queue)
237 {
238         return queue->listen_opt->qlen >> queue->listen_opt->max_qlen_log;
239 }
240
241 static inline void reqsk_queue_hash_req(struct request_sock_queue *queue,
242                                         u32 hash, struct request_sock *req,
243                                         unsigned long timeout)
244 {
245         struct listen_sock *lopt = queue->listen_opt;
246
247         req->expires = jiffies + timeout;
248         req->retrans = 0;
249         req->sk = NULL;
250         req->dl_next = lopt->syn_table[hash];
251
252         write_lock(&queue->syn_wait_lock);
253         lopt->syn_table[hash] = req;
254         write_unlock(&queue->syn_wait_lock);
255 }
256
257 #endif /* _REQUEST_SOCK_H */