/* * NET Generic infrastructure for Network protocols. * * Authors: Arnaldo Carvalho de Melo <acme@conectiva.com.br> * * From code originally in include/net/tcp.h * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version * 2 of the License, or (at your option) any later version. */ #include <linux/module.h> #include <linux/random.h> #include <linux/slab.h> #include <linux/string.h> #include <linux/vmalloc.h> #include <net/request_sock.h> /* * Maximum number of SYN_RECV sockets in queue per LISTEN socket. * One SYN_RECV socket costs about 80bytes on a 32bit machine. * It would be better to replace it with a global counter for all sockets * but then some measure against one socket starving all other sockets * would be needed. * * It was 128 by default. Experiments with real servers show, that * it is absolutely not enough even at 100conn/sec. 256 cures most * of problems. This value is adjusted to 128 for very small machines * (<=32Mb of memory) and to 1024 on normal or better ones (>=256Mb). * Note : Dont forget somaxconn that may limit backlog too. */ int sysctl_max_syn_backlog = 256; EXPORT_SYMBOL(sysctl_max_syn_backlog); int reqsk_queue_alloc(struct request_sock_queue *queue, unsigned int nr_table_entries) { size_t lopt_size = sizeof(struct listen_sock); struct listen_sock *lopt; nr_table_entries = min_t(u32, nr_table_entries, sysctl_max_syn_backlog); nr_table_entries = max_t(u32, nr_table_entries, 8); nr_table_entries = roundup_pow_of_two(nr_table_entries + 1); lopt_size += nr_table_entries * sizeof(struct request_sock *); if (lopt_size > PAGE_SIZE) lopt = vzalloc(lopt_size); else lopt = kzalloc(lopt_size, GFP_KERNEL); if (lopt == NULL) return -ENOMEM; for (lopt->max_qlen_log = 3; (1 << lopt->max_qlen_log) < nr_table_entries; lopt->max_qlen_log++); get_random_bytes(&lopt->hash_rnd, sizeof(lopt->hash_rnd)); rwlock_init(&queue->syn_wait_lock); queue->rskq_accept_head = NULL; lopt->nr_table_entries = nr_table_entries; write_lock_bh(&queue->syn_wait_lock); queue->listen_opt = lopt; write_unlock_bh(&queue->syn_wait_lock); return 0; } void __reqsk_queue_destroy(struct request_sock_queue *queue) { struct listen_sock *lopt; size_t lopt_size; /* * this is an error recovery path only * no locking needed and the lopt is not NULL */ lopt = queue->listen_opt; lopt_size = sizeof(struct listen_sock) + lopt->nr_table_entries * sizeof(struct request_sock *); if (lopt_size > PAGE_SIZE) vfree(lopt); else kfree(lopt); } static inline struct listen_sock *reqsk_queue_yank_listen_sk( struct request_sock_queue *queue) { struct listen_sock *lopt; write_lock_bh(&queue->syn_wait_lock); lopt = queue->listen_opt; queue->listen_opt = NULL; write_unlock_bh(&queue->syn_wait_lock); return lopt; } void reqsk_queue_destroy(struct request_sock_queue *queue) { /* make all the listen_opt local to us */ struct listen_sock *lopt = reqsk_queue_yank_listen_sk(queue); size_t lopt_size = sizeof(struct listen_sock) + lopt->nr_table_entries * sizeof(struct request_sock *); if (lopt->qlen != 0) { unsigned int i; for (i = 0; i < lopt->nr_table_entries; i++) { struct request_sock *req; while ((req = lopt->syn_table[i]) != NULL) { lopt->syn_table[i] = req->dl_next; lopt->qlen--; reqsk_free(req); } } } WARN_ON(lopt->qlen != 0); if (lopt_size > PAGE_SIZE) vfree(lopt); else kfree(lopt); }