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 */ 256