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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
  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         u32                             secid;
  57         u32                             peer_secid;
  58 };
  59
  60 static inline struct request_sock *reqsk_alloc(struct request_sock_ops *ops)
  61 {
  62         struct request_sock *req = kmem_cache_alloc(ops->slab, SLAB_ATOMIC);
  63
  64         if (req != NULL)
  65                 req->rsk_ops = ops;
  66
  67         return req;
  68 }
  69
  70 static inline void __reqsk_free(struct request_sock *req)
  71 {
  72         kmem_cache_free(req->rsk_ops->slab, req);
  73 }
  74
  75 static inline void reqsk_free(struct request_sock *req)
  76 {
  77         req->rsk_ops->destructor(req);
  78         __reqsk_free(req);
  79 }
  80
  81 extern int sysctl_max_syn_backlog;
  82
  83 /** struct listen_sock - listen state
  84  *
  85  * @max_qlen_log - log_2 of maximal queued SYNs/REQUESTs
  86  */
  87 struct listen_sock {
  88         u8                      max_qlen_log;
  89         /* 3 bytes hole, try to use */
  90         int                     qlen;
  91         int                     qlen_young;
  92         int                     clock_hand;
  93         u32                     hash_rnd;
  94         u32                     nr_table_entries;
  95         struct request_sock     *syn_table[0];
  96 };
  97
  98 /** struct request_sock_queue - queue of request_socks
  99  *
 100  * @rskq_accept_head - FIFO head of established children
 101  * @rskq_accept_tail - FIFO tail of established children
 102  * @rskq_defer_accept - User waits for some data after accept()
 103  * @syn_wait_lock - serializer
 104  *
 105  * %syn_wait_lock is necessary only to avoid proc interface having to grab the main
 106  * lock sock while browsing the listening hash (otherwise it's deadlock prone).
 107  *
 108  * This lock is acquired in read mode only from listening_get_next() seq_file
 109  * op and it's acquired in write mode _only_ from code that is actively
 110  * changing rskq_accept_head. All readers that are holding the master sock lock
 111  * don't need to grab this lock in read mode too as rskq_accept_head. writes
 112  * are always protected from the main sock lock.
 113  */
 114 struct request_sock_queue {
 115         struct request_sock     *rskq_accept_head;
 116         struct request_sock     *rskq_accept_tail;
 117         rwlock_t                syn_wait_lock;
 118         u8                      rskq_defer_accept;
 119         /* 3 bytes hole, try to pack */
 120         struct listen_sock      *listen_opt;
 121 };
 122
 123 extern int reqsk_queue_alloc(struct request_sock_queue *queue,
 124                              const int nr_table_entries);
 125
 126 static inline struct listen_sock *reqsk_queue_yank_listen_sk(struct request_sock_queue *queue)
 127 {
 128         struct listen_sock *lopt;
 129
 130         write_lock_bh(&queue->syn_wait_lock);
 131         lopt = queue->listen_opt;
 132         queue->listen_opt = NULL;
 133         write_unlock_bh(&queue->syn_wait_lock);
 134
 135         return lopt;
 136 }
 137
 138 static inline void __reqsk_queue_destroy(struct request_sock_queue *queue)
 139 {
 140         kfree(reqsk_queue_yank_listen_sk(queue));
 141 }
 142
 143 extern void reqsk_queue_destroy(struct request_sock_queue *queue);
 144
 145 static inline struct request_sock *
 146         reqsk_queue_yank_acceptq(struct request_sock_queue *queue)
 147 {
 148         struct request_sock *req = queue->rskq_accept_head;
 149
 150         queue->rskq_accept_head = NULL;
 151         return req;
 152 }
 153
 154 static inline int reqsk_queue_empty(struct request_sock_queue *queue)
 155 {
 156         return queue->rskq_accept_head == NULL;
 157 }
 158
 159 static inline void reqsk_queue_unlink(struct request_sock_queue *queue,
 160                                       struct request_sock *req,
 161                                       struct request_sock **prev_req)
 162 {
 163         write_lock(&queue->syn_wait_lock);
 164         *prev_req = req->dl_next;
 165         write_unlock(&queue->syn_wait_lock);
 166 }
 167
 168 static inline void reqsk_queue_add(struct request_sock_queue *queue,
 169                                    struct request_sock *req,
 170                                    struct sock *parent,
 171                                    struct sock *child)
 172 {
 173         req->sk = child;
 174         sk_acceptq_added(parent);
 175
 176         if (queue->rskq_accept_head == NULL)
 177                 queue->rskq_accept_head = req;
 178         else
 179                 queue->rskq_accept_tail->dl_next = req;
 180
 181         queue->rskq_accept_tail = req;
 182         req->dl_next = NULL;
 183 }
 184
 185 static inline struct request_sock *reqsk_queue_remove(struct request_sock_queue *queue)
 186 {
 187         struct request_sock *req = queue->rskq_accept_head;
 188
 189         BUG_TRAP(req != NULL);
 190
 191         queue->rskq_accept_head = req->dl_next;
 192         if (queue->rskq_accept_head == NULL)
 193                 queue->rskq_accept_tail = NULL;
 194
 195         return req;
 196 }
 197
 198 static inline struct sock *reqsk_queue_get_child(struct request_sock_queue *queue,
 199                                                  struct sock *parent)
 200 {
 201         struct request_sock *req = reqsk_queue_remove(queue);
 202         struct sock *child = req->sk;
 203
 204         BUG_TRAP(child != NULL);
 205
 206         sk_acceptq_removed(parent);
 207         __reqsk_free(req);
 208         return child;
 209 }
 210
 211 static inline int reqsk_queue_removed(struct request_sock_queue *queue,
 212                                       struct request_sock *req)
 213 {
 214         struct listen_sock *lopt = queue->listen_opt;
 215
 216         if (req->retrans == 0)
 217                 --lopt->qlen_young;
 218
 219         return --lopt->qlen;
 220 }
 221
 222 static inline int reqsk_queue_added(struct request_sock_queue *queue)
 223 {
 224         struct listen_sock *lopt = queue->listen_opt;
 225         const int prev_qlen = lopt->qlen;
 226
 227         lopt->qlen_young++;
 228         lopt->qlen++;
 229         return prev_qlen;
 230 }
 231
 232 static inline int reqsk_queue_len(const struct request_sock_queue *queue)
 233 {
 234         return queue->listen_opt != NULL ? queue->listen_opt->qlen : 0;
 235 }
 236
 237 static inline int reqsk_queue_len_young(const struct request_sock_queue *queue)
 238 {
 239         return queue->listen_opt->qlen_young;
 240 }
 241
 242 static inline int reqsk_queue_is_full(const struct request_sock_queue *queue)
 243 {
 244         return queue->listen_opt->qlen >> queue->listen_opt->max_qlen_log;
 245 }
 246
 247 static inline void reqsk_queue_hash_req(struct request_sock_queue *queue,
 248                                         u32 hash, struct request_sock *req,
 249                                         unsigned long timeout)
 250 {
 251         struct listen_sock *lopt = queue->listen_opt;
 252
 253         req->expires = jiffies + timeout;
 254         req->retrans = 0;
 255         req->sk = NULL;
 256         req->dl_next = lopt->syn_table[hash];
 257
 258         write_lock(&queue->syn_wait_lock);
 259         lopt->syn_table[hash] = req;
 260         write_unlock(&queue->syn_wait_lock);
 261 }
 262
 263 #endif /* _REQUEST_SOCK_H */