2 * NET Generic infrastructure for Network protocols.
4 * Definitions for request_sock
6 * Authors: Arnaldo Carvalho de Melo <acme@conectiva.com.br>
8 * From code originally in include/net/tcp.h
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.
15 #ifndef _REQUEST_SOCK_H
16 #define _REQUEST_SOCK_H
18 #include <linux/slab.h>
19 #include <linux/spinlock.h>
20 #include <linux/types.h>
21 #include <linux/bug.h>
30 struct request_sock_ops {
33 struct kmem_cache *slab;
35 int (*rtx_syn_ack)(struct sock *sk,
36 struct request_sock *req);
37 void (*send_ack)(struct sock *sk, struct sk_buff *skb,
38 struct request_sock *req);
39 void (*send_reset)(struct sock *sk,
41 void (*destructor)(struct request_sock *req);
44 /* struct request_sock - mini sock to represent a connection request
47 struct request_sock *dl_next; /* Must be first member! */
50 u8 cookie_ts; /* syncookie: encode tcpopts in timestamp */
51 /* The following two fields can be easily recomputed I think -AK */
52 u32 window_clamp; /* window clamp at creation time */
53 u32 rcv_wnd; /* rcv_wnd offered first time */
55 unsigned long expires;
56 const struct request_sock_ops *rsk_ops;
62 static inline struct request_sock *reqsk_alloc(const struct request_sock_ops *ops)
64 struct request_sock *req = kmem_cache_alloc(ops->slab, GFP_ATOMIC);
72 static inline void __reqsk_free(struct request_sock *req)
74 kmem_cache_free(req->rsk_ops->slab, req);
77 static inline void reqsk_free(struct request_sock *req)
79 req->rsk_ops->destructor(req);
83 extern int sysctl_max_syn_backlog;
85 /** struct listen_sock - listen state
87 * @max_qlen_log - log_2 of maximal queued SYNs/REQUESTs
91 /* 3 bytes hole, try to use */
97 struct request_sock *syn_table[0];
100 /** struct request_sock_queue - queue of request_socks
102 * @rskq_accept_head - FIFO head of established children
103 * @rskq_accept_tail - FIFO tail of established children
104 * @rskq_defer_accept - User waits for some data after accept()
105 * @syn_wait_lock - serializer
107 * %syn_wait_lock is necessary only to avoid proc interface having to grab the main
108 * lock sock while browsing the listening hash (otherwise it's deadlock prone).
110 * This lock is acquired in read mode only from listening_get_next() seq_file
111 * op and it's acquired in write mode _only_ from code that is actively
112 * changing rskq_accept_head. All readers that are holding the master sock lock
113 * don't need to grab this lock in read mode too as rskq_accept_head. writes
114 * are always protected from the main sock lock.
116 struct request_sock_queue {
117 struct request_sock *rskq_accept_head;
118 struct request_sock *rskq_accept_tail;
119 rwlock_t syn_wait_lock;
120 u8 rskq_defer_accept;
121 /* 3 bytes hole, try to pack */
122 struct listen_sock *listen_opt;
125 extern int reqsk_queue_alloc(struct request_sock_queue *queue,
126 unsigned int nr_table_entries);
128 extern void __reqsk_queue_destroy(struct request_sock_queue *queue);
129 extern void reqsk_queue_destroy(struct request_sock_queue *queue);
131 static inline struct request_sock *
132 reqsk_queue_yank_acceptq(struct request_sock_queue *queue)
134 struct request_sock *req = queue->rskq_accept_head;
136 queue->rskq_accept_head = NULL;
140 static inline int reqsk_queue_empty(struct request_sock_queue *queue)
142 return queue->rskq_accept_head == NULL;
145 static inline void reqsk_queue_unlink(struct request_sock_queue *queue,
146 struct request_sock *req,
147 struct request_sock **prev_req)
149 write_lock(&queue->syn_wait_lock);
150 *prev_req = req->dl_next;
151 write_unlock(&queue->syn_wait_lock);
154 static inline void reqsk_queue_add(struct request_sock_queue *queue,
155 struct request_sock *req,
160 sk_acceptq_added(parent);
162 if (queue->rskq_accept_head == NULL)
163 queue->rskq_accept_head = req;
165 queue->rskq_accept_tail->dl_next = req;
167 queue->rskq_accept_tail = req;
171 static inline struct request_sock *reqsk_queue_remove(struct request_sock_queue *queue)
173 struct request_sock *req = queue->rskq_accept_head;
175 WARN_ON(req == NULL);
177 queue->rskq_accept_head = req->dl_next;
178 if (queue->rskq_accept_head == NULL)
179 queue->rskq_accept_tail = NULL;
184 static inline struct sock *reqsk_queue_get_child(struct request_sock_queue *queue,
187 struct request_sock *req = reqsk_queue_remove(queue);
188 struct sock *child = req->sk;
190 WARN_ON(child == NULL);
192 sk_acceptq_removed(parent);
197 static inline int reqsk_queue_removed(struct request_sock_queue *queue,
198 struct request_sock *req)
200 struct listen_sock *lopt = queue->listen_opt;
202 if (req->retrans == 0)
208 static inline int reqsk_queue_added(struct request_sock_queue *queue)
210 struct listen_sock *lopt = queue->listen_opt;
211 const int prev_qlen = lopt->qlen;
218 static inline int reqsk_queue_len(const struct request_sock_queue *queue)
220 return queue->listen_opt != NULL ? queue->listen_opt->qlen : 0;
223 static inline int reqsk_queue_len_young(const struct request_sock_queue *queue)
225 return queue->listen_opt->qlen_young;
228 static inline int reqsk_queue_is_full(const struct request_sock_queue *queue)
230 return queue->listen_opt->qlen >> queue->listen_opt->max_qlen_log;
233 static inline void reqsk_queue_hash_req(struct request_sock_queue *queue,
234 u32 hash, struct request_sock *req,
235 unsigned long timeout)
237 struct listen_sock *lopt = queue->listen_opt;
239 req->expires = jiffies + timeout;
242 req->dl_next = lopt->syn_table[hash];
244 write_lock(&queue->syn_wait_lock);
245 lopt->syn_table[hash] = req;
246 write_unlock(&queue->syn_wait_lock);
249 #endif /* _REQUEST_SOCK_H */