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