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
  22 #include <net/sock.h>
  23
  24 struct request_sock;
  25 struct sk_buff;
  26 struct dst_entry;
  27 struct proto;
  28
  29 struct request_sock_ops {
  30         int             family;
  31         kmem_cache_t    *slab;
  32         int             obj_size;
  33         int             (*rtx_syn_ack)(struct sock *sk,
  34                                        struct request_sock *req,
  35                                        struct dst_entry *dst);
  36         void            (*send_ack)(struct sk_buff *skb,
  37                                     struct request_sock *req);
  38         void            (*send_reset)(struct sk_buff *skb);
  39         void            (*destructor)(struct request_sock *req);
  40 };
  41
  42 /* struct request_sock - mini sock to represent a connection request
  43  */
  44 struct request_sock {
  45         struct request_sock             *dl_next; /* Must be first member! */
  46         u16                             mss;
  47         u8                              retrans;
  48         u8                              __pad;
  49         /* The following two fields can be easily recomputed I think -AK */
  50         u32                             window_clamp; /* window clamp at creation time */
  51         u32                             rcv_wnd;          /* rcv_wnd offered first time */
  52         u32                             ts_recent;
  53         unsigned long                   expires;
  54         struct request_sock_ops         *rsk_ops;
  55         struct sock                     *sk;
  56 };
  57
  58 static inline struct request_sock *reqsk_alloc(struct request_sock_ops *ops)
  59 {
  60         struct request_sock *req = kmem_cache_alloc(ops->slab, SLAB_ATOMIC);
  61
  62         if (req != NULL)
  63                 req->rsk_ops = ops;
  64
  65         return req;
  66 }
  67
  68 static inline void __reqsk_free(struct request_sock *req)
  69 {
  70         kmem_cache_free(req->rsk_ops->slab, req);
  71 }
  72
  73 static inline void reqsk_free(struct request_sock *req)
  74 {
  75         req->rsk_ops->destructor(req);
  76         __reqsk_free(req);
  77 }
  78
  79 extern int sysctl_max_syn_backlog;
  80
  81 /** struct listen_sock - listen state
  82  *
  83  * @max_qlen_log - log_2 of maximal queued SYNs/REQUESTs
  84  */
  85 struct listen_sock {
  86         u8                      max_qlen_log;
  87         /* 3 bytes hole, try to use */
  88         int                     qlen;
  89         int                     qlen_young;
  90         int                     clock_hand;
  91         u32                     hash_rnd;
  92         struct request_sock     *syn_table[0];
  93 };
  94
  95 /** struct request_sock_queue - queue of request_socks
  96  *
  97  * @rskq_accept_head - FIFO head of established children
  98  * @rskq_accept_tail - FIFO tail of established children
  99  * @syn_wait_lock - serializer
 100  *
 101  * %syn_wait_lock is necessary only to avoid proc interface having to grab the main
 102  * lock sock while browsing the listening hash (otherwise it's deadlock prone).
 103  *
 104  * This lock is acquired in read mode only from listening_get_next() seq_file
 105  * op and it's acquired in write mode _only_ from code that is actively
 106  * changing rskq_accept_head. All readers that are holding the master sock lock
 107  * don't need to grab this lock in read mode too as rskq_accept_head. writes
 108  * are always protected from the main sock lock.
 109  */
 110 struct request_sock_queue {
 111         struct request_sock     *rskq_accept_head;
 112         struct request_sock     *rskq_accept_tail;
 113         rwlock_t                syn_wait_lock;
 114         struct listen_sock      *listen_opt;
 115 };
 116
 117 extern int reqsk_queue_alloc(struct request_sock_queue *queue,
 118                              const int nr_table_entries);
 119
 120 static inline struct listen_sock *reqsk_queue_yank_listen_sk(struct request_sock_queue *queue)
 121 {
 122         struct listen_sock *lopt;
 123
 124         write_lock_bh(&queue->syn_wait_lock);
 125         lopt = queue->listen_opt;
 126         queue->listen_opt = NULL;
 127         write_unlock_bh(&queue->syn_wait_lock);
 128
 129         return lopt;
 130 }
 131
 132 static inline void reqsk_queue_destroy(struct request_sock_queue *queue)
 133 {
 134         kfree(reqsk_queue_yank_listen_sk(queue));
 135 }
 136
 137 static 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 = queue->rskq_accept_head = NULL;
 143         return req;
 144 }
 145
 146 static inline int reqsk_queue_empty(struct request_sock_queue *queue)
 147 {
 148         return queue->rskq_accept_head == NULL;
 149 }
 150
 151 static 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
 160 static 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
 177 static inline struct request_sock *reqsk_queue_remove(struct request_sock_queue *queue)
 178 {
 179         struct request_sock *req = queue->rskq_accept_head;
 180
 181         BUG_TRAP(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
 190 static 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         BUG_TRAP(child != NULL);
 197
 198         sk_acceptq_removed(parent);
 199         __reqsk_free(req);
 200         return child;
 201 }
 202
 203 static 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
 214 static 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
 224 static inline int reqsk_queue_len(struct request_sock_queue *queue)
 225 {
 226         return queue->listen_opt != NULL ? queue->listen_opt->qlen : 0;
 227 }
 228
 229 static inline int reqsk_queue_len_young(struct request_sock_queue *queue)
 230 {
 231         return queue->listen_opt->qlen_young;
 232 }
 233
 234 static inline int reqsk_queue_is_full(struct request_sock_queue *queue)
 235 {
 236         return queue->listen_opt->qlen >> queue->listen_opt->max_qlen_log;
 237 }
 238
 239 static inline void reqsk_queue_hash_req(struct request_sock_queue *queue,
 240                                         u32 hash, struct request_sock *req,
 241                                         unsigned 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 */