LXR linux/include/net/request

   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
  25struct request_sock;
  26struct sk_buff;
  27struct dst_entry;
  28struct proto;
  29
  30struct request_sock_ops {
  31        int             family;
  32        int             obj_size;
  33        struct kmem_cache       *slab;
  34        char            *slab_name;
  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,
  40                                      struct sk_buff *skb);
  41        void            (*destructor)(struct request_sock *req);
  42};
  43
  44/* struct request_sock - mini sock to represent a connection request
  45 */
  46struct request_sock {
  47        struct request_sock             *dl_next; /* Must be first member! */
  48        u16                             mss;
  49        u8                              retrans;
  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 */
  54        u32                             ts_recent;
  55        unsigned long                   expires;
  56        const struct request_sock_ops   *rsk_ops;
  57        struct sock                     *sk;
  58        u32                             secid;
  59        u32                             peer_secid;
  60};
  61
  62static inline struct request_sock *reqsk_alloc(const struct request_sock_ops *ops)
  63{
  64        struct request_sock *req = kmem_cache_alloc(ops->slab, GFP_ATOMIC);
  65
  66        if (req != NULL)
  67                req->rsk_ops = ops;
  68
  69        return req;
  70}
  71
  72static inline void __reqsk_free(struct request_sock *req)
  73{
  74        kmem_cache_free(req->rsk_ops->slab, req);
  75}
  76
  77static inline void reqsk_free(struct request_sock *req)
  78{
  79        req->rsk_ops->destructor(req);
  80        __reqsk_free(req);
  81}
  82
  83extern int sysctl_max_syn_backlog;
  84
  85/** struct listen_sock - listen state
  86 *
  87 * @max_qlen_log - log_2 of maximal queued SYNs/REQUESTs
  88 */
  89struct listen_sock {
  90        u8                      max_qlen_log;
  91        /* 3 bytes hole, try to use */
  92        int                     qlen;
  93        int                     qlen_young;
  94        int                     clock_hand;
  95        u32                     hash_rnd;
  96        u32                     nr_table_entries;
  97        struct request_sock     *syn_table[0];
  98};
  99
 100/** struct request_sock_queue - queue of request_socks
 101 *
 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
 106 *
 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).
 109 *
 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.
 115 */
 116struct 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;
 123};
 124
 125extern int reqsk_queue_alloc(struct request_sock_queue *queue,
 126                             unsigned int nr_table_entries);
 127
 128extern void __reqsk_queue_destroy(struct request_sock_queue *queue);
 129extern void reqsk_queue_destroy(struct request_sock_queue *queue);
 130
 131static inline struct request_sock *
 132        reqsk_queue_yank_acceptq(struct request_sock_queue *queue)
 133{
 134        struct request_sock *req = queue->rskq_accept_head;
 135
 136        queue->rskq_accept_head = NULL;
 137        return req;
 138}
 139
 140static inline int reqsk_queue_empty(struct request_sock_queue *queue)
 141{
 142        return queue->rskq_accept_head == NULL;
 143}
 144
 145static inline void reqsk_queue_unlink(struct request_sock_queue *queue,
 146                                      struct request_sock *req,
 147                                      struct request_sock **prev_req)
 148{
 149        write_lock(&queue->syn_wait_lock);
 150        *prev_req = req->dl_next;
 151        write_unlock(&queue->syn_wait_lock);
 152}
 153
 154static inline void reqsk_queue_add(struct request_sock_queue *queue,
 155                                   struct request_sock *req,
 156                                   struct sock *parent,
 157                                   struct sock *child)
 158{
 159        req->sk = child;
 160        sk_acceptq_added(parent);
 161
 162        if (queue->rskq_accept_head == NULL)
 163                queue->rskq_accept_head = req;
 164        else
 165                queue->rskq_accept_tail->dl_next = req;
 166
 167        queue->rskq_accept_tail = req;
 168        req->dl_next = NULL;
 169}
 170
 171static inline struct request_sock *reqsk_queue_remove(struct request_sock_queue *queue)
 172{
 173        struct request_sock *req = queue->rskq_accept_head;
 174
 175        WARN_ON(req == NULL);
 176
 177        queue->rskq_accept_head = req->dl_next;
 178        if (queue->rskq_accept_head == NULL)
 179                queue->rskq_accept_tail = NULL;
 180
 181        return req;
 182}
 183
 184static inline struct sock *reqsk_queue_get_child(struct request_sock_queue *queue,
 185                                                 struct sock *parent)
 186{
 187        struct request_sock *req = reqsk_queue_remove(queue);
 188        struct sock *child = req->sk;
 189
 190        WARN_ON(child == NULL);
 191
 192        sk_acceptq_removed(parent);
 193        __reqsk_free(req);
 194        return child;
 195}
 196
 197static inline int reqsk_queue_removed(struct request_sock_queue *queue,
 198                                      struct request_sock *req)
 199{
 200        struct listen_sock *lopt = queue->listen_opt;
 201
 202        if (req->retrans == 0)
 203                --lopt->qlen_young;
 204
 205        return --lopt->qlen;
 206}
 207
 208static inline int reqsk_queue_added(struct request_sock_queue *queue)
 209{
 210        struct listen_sock *lopt = queue->listen_opt;
 211        const int prev_qlen = lopt->qlen;
 212
 213        lopt->qlen_young++;
 214        lopt->qlen++;
 215        return prev_qlen;
 216}
 217
 218static inline int reqsk_queue_len(const struct request_sock_queue *queue)
 219{
 220        return queue->listen_opt != NULL ? queue->listen_opt->qlen : 0;
 221}
 222
 223static inline int reqsk_queue_len_young(const struct request_sock_queue *queue)
 224{
 225        return queue->listen_opt->qlen_young;
 226}
 227
 228static inline int reqsk_queue_is_full(const struct request_sock_queue *queue)
 229{
 230        return queue->listen_opt->qlen >> queue->listen_opt->max_qlen_log;
 231}
 232
 233static inline void reqsk_queue_hash_req(struct request_sock_queue *queue,
 234                                        u32 hash, struct request_sock *req,
 235                                        unsigned long timeout)
 236{
 237        struct listen_sock *lopt = queue->listen_opt;
 238
 239        req->expires = jiffies + timeout;
 240        req->retrans = 0;
 241        req->sk = NULL;
 242        req->dl_next = lopt->syn_table[hash];
 243
 244        write_lock(&queue->syn_wait_lock);
 245        lopt->syn_table[hash] = req;
 246        write_unlock(&queue->syn_wait_lock);
 247}
 248
 249#endif /* _REQUEST_SOCK_H */
 250