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