request_sock.h 6.4 KB

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