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